CA1288516C - Apparatus and method for communicating textual and image information between a host computer and a remote display terminal - Google Patents

Abstract

ABSTRACT

A system and method for storing, retrieving, displaying, printing and otherwise manipulating color images stored in a central "host" computer from a realtor's remote data terminal includes a host computer which stores and maintains a database containing listings of real estate properties on the market. The host computer also optionally can store image information relating to specific properties. Images can be loaded from remote terminals over telephone lines to the host system on an inter-active basis. Images can then be retrieved from the host system, also on an interactive basis, for display, printing, or storage on a storage medium associated with the remote display terminals.
Images may also be deleted on an interactive basis from a remote terminal. A specific communications protocol conveys image data between the host computer and remote data terminals. This protocol includes specific "time-out" limitations, CRC error checking schemes, and a specific "handshaking" signalling sequence that must be observed before the host system will permit manipula-tion of image files.

Description

APPARATUS AND METaOD FOR COMMUNICAT_NG TEXTUAL
AND IMAGE INFORMATION B TWEEN A HOST_COMPUTER AND A
REMOTE DISPLAY TE~MINAL

FIELD OE T~E INVENTION

The present invention re:Lates to communication o~ text and image data between a host computer and a remote display terminal. More particularly, the invention relates to a system and method for storing, manipulating, retrieving and displaying images and text associated with real estate properties being offered for sale, and to a protocol for communicating real estate listing text and images of properties for sale between a host computer and a remote data terminal.
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S P E C I F I C A T I O N

The ability of real estate agents and brokers to instantly access information relating to properties on the market often makes the difference between making or losing a sale. Typically, real estate agents rely upon printed listings and computer-stored information that can be displayed on a computer display screen or p~lnt~d on a computer printer. However, agents cannot easily match the needs and desires of a prospective customer with specific properties without actually touring the properties with the customer -- a proce~s which is extremely time consuming and can often turn out to be ,.
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a waste of time.

Textual lis-ting information such as that provlded by the m~lltiple llstlng ~ervice ("MLS") is usually very help~ul in identifying properties that may be of interest to specific c~tstomer~, but often fail~ to provide sufficient information to exclude properties that customers would immediately re~ect from their consideration ~Ipon merely viewing the property from the exterior. Sometimes, published photographs (typically only black and white) are available which ~how some of the features of propertie~. Unfortunately, such photograph~ are generally poorly composed, are of relatively low quality, are poorly reproduced, and are not always widely or rapidly distributed to realtors.
Automated real estate system~ which allow realtor~ to acces~ image as well as textual information are generally known. For example, Micro~oft Corp., I/NET, Inc., Board of Realty Inormation Sy~tems ("BORIS), and AT~T all have developed automated real e~tate listing services which provide images as well as text. The following is a by no means exhaustive listin~ of repre~entative publications whlch are generally relevant in showing the state of the art of such imaqil-g systems:

"Three Bedrooms, Two Bath~, ~ne Mac", Heid, J., Macworld, Vol. 2, No. 8, A~lg. 1985, pp.
120.
"Southwestern Michigan'~ Knapp Introduces Unique Real Estate System", ~non, ~ata Manaaement, Vol. 22, No. 8, ~u~. 198~, pp. 46, 54.
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~ 28~35~i "PC~ Prove to be the Real Estate Thing", Freedman, E., PC (Inde~_dent Guide to IBM
Personal Com~uters), Vol. 4, No. 5, March S, 1985, p. 60.
"Bori 8 Add~ Imaging Options to System", Polilli, S. MIS Week, Vo]L. 6, No. l, Jan. 2, 1985, p. 25. . -"AT~T Joins Realtors in E~ome Sales", Greenstein, I. MIS Week, Vol. 5, No. 26, June 27, 1984, pp~ l, 30.
However, many further iMprovemsnts in SUCl 3ystems are ~till possible.
For example, most prior systems only operate in a "local" mode -- meaning that display terminals capable of displaying images mu~t be lnstalled within clo3e proximity to the central "host"
computer which stora~ and manipulates the image and text lnformation. Typically, howev~r, realty offices are unwilling to undertake -the expense of purchasing and maintaining a larga minicomputer and a3sociated database, relying instead on inexpensive data terminals or microcomputers (e.g., IB~ PC
compatibles) connected to a large central computer via modems and conventiona} telephone line~.
Tran~misYion of color image~ of acceptable quallty from a host computer to a data terminal over a telephone line i9 difficult, e~p~c1fllly in view of the noise 1nherent on conventiol1~l. telephone llnes, banddwidth limitations, telepltone Iine equipment ~.
response3 to transmitted data of telephone lines, and other artors. Yot, limiting imagin~
capabilitie~ to only those displ~y terminals installed in the same facility ~ the host computer ~-prevents th~e vast majority o renltors from u~ing ~.
*Trade-mark - .- . . ~ , . .

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~1 2~ 16 those capabilities.
In addition, there has heretofore been no capability to digitize images on a remote display terminal and transmit the resulting digital signal information on a real time, interactive basis to the host computer. The ability to add images of properties to the host computer database in real time on an interactive basis from remote display terminals would make the images available immediately after they are converted to digital form. In today's fast-moving and competitive real estate market, an agent must have immediate access to all available information about new property listings in order to serve his or her clients effectively. Providing remote terminals with the capability of adding images to the host database encourages the use of the system's imaging capability, but also creates additional problems relating to data~ase integrity (e.g., accidental storing of images in connection with incorrect property listings, and servicing conflicting user re~uests regarding images for the same listing) which must be solved.
The present invention provides a highly advantageous system and method for storing, retrieving, displaying, printing and otherwise manipulating color images stor~-l In a central "host"
computer from a realtor's remote data terminal.
Briefly, the host computer stores and maintains a database containing listings of real estate properties on the market. The host computer also optionally can store image inform~tion relating to specific properties. Images Catl bR lo~ded from , . . . ; . . -.

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remote terminals over telephone lines to the host system on an interactive basis. Images can then be retrieved from the host system, also on an interactive basis, for display, printing, or storage on a storage medium associated with the remote display terminals. Images ma~ also be delete~ on an interactive basis from a remote terminal.
The preferred embodimen~ of the present invention thus allows users of IBM PCs (or other appropriately configured display terminals) wlth the appropriate software to access a photo file on the host system to add, delete, or retrieve and display photos corresponding to properties listed for sale.
The present invention provides the capability to transmit the photo data in either direction between the PDP-ll host and the display terminal in order to store photos in or retrieve photos from the - -host photo file. Photos may also ~e deleted from remote display terminals.
A specific communications protocol conveys image data between the host computer and remote data terminals. This protocol includes specific "time-out" limitations, CRC error checking schemes, and a specific "handshaking" signalling sequence that must be observed before the host system will permit manipulation of image files. In addition, the protocol is for "dial-llp" lines -- so that standard telephone equipment alld mod~lms do not erroneously recognize protocol characters for control character~ relevant to their own operation.
Eor e~ample, to retrieve an imaqq on the host computer, a remote terminal user ~.elepllones the host computer ~via a conventional "mod~m" ~nd landline - .: , : : :

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~1 2~3~35~6 communications path) and searches standard "multiple listing ~ervice" (MLS) Listings in a st~ndard mann~r. Once a specific li~ting of interest has been iRolated, the user inputs a command ("P~O") through his terminal requesting the photo function.
The host computer then poll~ ~he terminal to determine if the terminal has the appropriate graphics capabilities.
If the poll i9 successful, the user is prompted or the MLS listing number of the listing of interest. The MLS number i9 validated, and a "mini-form" consisting o current MLS database fields (e.g., property price reflecting all chan~es to date) i8 displayed at the bottom oE the screen.
Following transmlssion of the "mini-form", a digitized image is transmitted and displayed at the upper l~ft of the t~rminal display. Error checlcing algorlthms are applied to the incoming host image data. A full textual listing is then transmitted.
The user can "flip" between a text screen ~howing the full li~ting and a qraphics screen showing the "mini-form" and the image.
If there are multiple photos a~sociated wlth the same listing, the user ~ 8 prompted to specify whether the "next" photo is to be displayed.
Subsequent images are displayec1 ~1 t1~e upper right-hand quadraht of the grflpht~ ~creen, the full text of the li-Rting not being t7~ mltted between subse~uent images. The software executing on the data terminal permits the u~er to display image , print imaqes, or ~tore image~ on a local magnetic storage medium for later recall.
Images are stored on the 110R~ ~y~t~m in f1les . ,~,'~

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indexed by a single key consisting of the concatenation of the MLS number, a single character photo nwnber, and a single character photo ~egment number. Users can add images to the host database from their remote data terminals in an in-teractive mode. When the user invokes ~-hb "add photo" routine (command SPH), the host polls the data terminal to ensure it has graphics capture capabilities, and then prompts the user for a ~LS number. The geographic street address of the associated property is then displayed for verification by the user (while nine-digit MLS numbers are often confused, addresses are more readily recognized by users), along with an indication of the number of images already stored by the host which relate to the property of interest.
After the user assigns the new image a photo number, the user display terminal begins lnteractively scanning a video signal (e.g., produced by a video camera), digitizing and compre~sing the image ~ignal, and transmitting the resulting digital signal to the host for storage.
Image capture is performed on a real time, interactive basis -- helping to preserve database integrity and providing access to images by others virtually immediately after the u~er has added the image.to the host database. Tlle host provides positive acknowledgment that the new image has been added, and p~rmits the user to enter additional image~ for the same or different listings if desired.
A single image file manager execute~ on the host system to manage image fi les . Tlle use of a single manager prevents multip]e u~ers from .... . . . . .

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performing duplicate or conflicting image operations on the same images.
The photo capabilities are integrated into the existing Moore Data Management's REAL-TRIEVE real estate listing text access system to the extent that the existing log in and autho~ization procedures are used to first access the REAL-TRIEVE system. After access, three new photo commands may be issued by the user:

PHO - The "photo" command To retrieve an existing photo from the host photo file and display it on the ~ser's display terminal.

SPH - the "add photo" command To add a new photo to the host photo file by transmitting the picture data from tha user's display terminal to the host.
' DPH - the "delete photo" command To delete an existing photo from the ho~t photo file.

The present invention thus provides a tool that now brings property listings to life in full-color pictures that appear on the comp~lter display screen, along with text describing the property. If equipped with a color printer, the image on the screen, along with the text, can be printed to become a "saIe~ brochure" for the agent to give the client.
The sy~tem provided by the pr~ent invention 12~ 6 enables real estate agencies to "sell" the client on visually acceptable properties wi-thout the expense of numerous trips to proper-ties. In addition, the system is superior to any published real estate listings which show only one view of a house or apartment. High-quality color- images can be generated with up to sixteen separate views available of a property, including both interior and exterior views, if desired. Since each picture takes less than thirty seconds to produce, it is available in less time than it takes to retrieve a folder from a file cabinet.
Once connec-ted to the host computer over a telephone line, a computer in the office is capable of receiving both text and photographs in just moments. Selected li~tings, including photographs, can be stored for later u~e in display terminal local storage. A library of photographs can be prepared for specific client. The client can even be visited at home, with a portable computer display screen, or with photographs and text in the sales brochure format that have been preprinted before the visit.
Some of the advantages and capabilities of the sy~tem provided by the present invention include:

Retrieval of property li~ti llg8 from the on~line information system, flnd displaying, printing and storing of sucl~ files in a text file on disk.

Retrieval of photographs as~ocl~ted with the property listings from the n~ e information . , , . ~ .. . . - : , ~ .

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system and dlsplay of up to sixteen photograph~
viewing the property.

Changing of displayed pages between the complete descriptive text and the photographs of the property displaye~.~

Storing photographs in files on a disk for later access.

When a user display station is not connected to the host on-line sys-tem, users can still perform the following tasks:

Recall information previously stored on the disk o~ both text and photographs, and produce both on a display screen or printer.

Transport the stored disk information to a compatible portable computer.

The recall feature provides users with the flexibility to pick and choose at will those li~tings applica~le to specific clients. The transport capability allows users to provide the client with preselected photogr~phs ~nd tex~ of prope~ties which can then be preRented to clients even in the convenience of the client' 8 own home.
The user interface software in the preferred embodiment i~ "menu driven" -- meaning that all these valuable features are performed ~IAing ea~y-to-understand computer menu~ whlcll flppear on the computer display screen. A men~l ~ 8 simply a '' . " ' :

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listing of choices of features that can be used.
Making ~ menu choice result:s in the activation of a sy~tem function. Rather than typing in complicated commands, functions are performed by pressing designated function keys which are numbered from one to ten. Each key is referenced-on a menu display whenever a function can be performed with it.

BRIEF DESCRIPTION OF T~E DRAWINGS

These and other features and advantages of the present invention may be better and more completely under3tood by studying the following detailed description of the presently preferred embodiments together with the appended drawings of which:
FIGURE 1 i~ a block diagram of the presently preferred exemplary embodiment of a text and graphics communication system in accordance with the present invention;

FIGURE 2 is a schematic flowchart of tasks perormed by the ho~t computer shown in FIGURE l;

FIGURE 3 is a schematic diagram of an exemplary remote display terminal shown in FIGURE l;

FIGURE 4 is a schematic d~r~m of the rear panel of the FIGURE 3 processor modllîe;

FIGURES 5A-5C are shematic diagrams showing the resolution of the images produced by tl-a FIGURE 1 system; -, ' ~

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~2~3~35~6 FIGURE 6 is a schematic diagram of the user menu structure displayed by the EIGURE 1 remote display station;

FIGURE 7 is a schematic diagram of an exemplary host image data file formats;.and FIGURE 8 - 26 are 1Owcharts of exemplary program control steps performed by the system shown in FIGURE 1.

DETAILED DESCRIPTION OF PRESENTLY
PREFERRED EXEMPLARY_~MBODIME~r FIGURE 1 is a schematic block diagra~ of a presently preferred exemplary embodiment of a data processing system 100 in accordance with the present invention. System 100 includes a host computer system 200 and a remote computer system 300 connected together in the preferred embodiment by a conventional voice,quality "dial up" telephone line 400.
- In the preferred embodiment, host computer sy~tem 200 includes a processor 202 and associated random access memory 204, a mass storage device (e.g., magnetic disk) 206, and a ~erial co~munications facility 208. In th~ preferred embodiment, processor 202 incllld~ a Digital Eguipment Corp. PDP-11/84 proceRsor having internal random acce~s memory 204 and r~lnning under the RSX-llM operating system. Mass stor~q~ device 206 may include a 160 megabyte (or l~rg~t-) Winchester "hard" disk, and conventional D% cnmmlltlication ports :

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385~6 may be used for comm~nlcation faci~lity 208.
Dislc 206 ~tores a databa~e which include~ files containing imag~Y corresponding to listed properties. Communication~ facility 208 permlts remote display terminals 300 to e~tablish communications with processor 202 and request t~e proces~or to manipulate the image files stored on dis]c 206 (several display terminal~ preerably may access the processor at the 9 lme time). Proce~sor 202 executes sotware in the preferred embodiment which implements several functions, including a sign-on task, an image ile manager, PHOTOFILE
tasks, and REAL-TRIEVE listing text retrleval tasks. The task~ performed by proce~sor 202 to search add, retrieve, alter and delete "multiple listing service" real estate listing text information ~which i3 stored in a database on disk 206 different from the image disk) are conventional and known to those o~ ordinary skill in this art.
The REAL~TRIEVE System developed by the assignee of the ~ub~ect application (which ha~ been in public u~e for guite ~ome time and formerly did not include any imaging capability) utilizes the following:

PDP-ll with RSX-llM oper~ting system Hard disk ~torage DZ-communication ports . REAL-TRIEVE ~oftware using these termlnals:

. TI silent 700 hard copy t~rmlllnls;

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. VT-100 terminals/modems.

The REAL-TRIEVE Sy3tem is accessed via telephone and one of the terminals mentioned above. Once connected, real estate listinqs can be searched and displayed through the REAL-T~I-E~E System.
The following is additional eq~lipment u~ed for the preferred embodiment of the pre~ent invention to provide imaging as well as textual capabilities:

Additional HA~D DISK or photo storage (on PDP-11 host computer) PHOTO-TRIEVE software (runs on PDP-11 host ~ystem) IBM/PC (128K minimum memory, communication port, color monitor) AT&T Graphics Card~
PHOTO-TERM and PHOTO-STORE Terminal Software The IBM-PC (or compatible) functions as a ~`
display terminal with proprietary PHOTO-TRIEVE
terminal software. Thi~ software al80 allows digitized photos to be transmitted from the PDP-11 host to the IBM-PC terminal. Tl~e gr~phics card then dispLays the photo.
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HOST ARCHITECTURE

The host image file manager executed by proce~sor 202 (see FIGURE 1~ perform~ t~s on the image files stored on disk 206. In the preferred ; , , - -, - - ; . . .

~.~885~6 embodiment, thl~ ~oftware was written in FORTRAN IV
and Macro 11 a~sembly language. Task~ executed by the image Eile manager lnclude a~dlng images Ithe "SPR", or "add photo" task), retrievinq images ~the "PHO", or "photo" tas1c), and deleting images tthe "DPH", or "delete photo" comm~nd). The~e ta~1cs are performed by corresponding software modules to be discussed shortly. FIGURE 2 schematically shows the relationship between the variot1s program control modules performed by host processor 2~2.
When processor 202 first begins executing REAL-TRIEVE software, lt exe~utes a "sign-on" module 225 which, for example, permits user display terminal~ to begin communicatin~ with the processor via communications facility 208, and performs the various tasks as~ociated with the MLS (multiple listing service) database.
A "PHOTO-FILE" u~er interface module 226 interface~ the ~ign on module 225 with an image file manager (PEM) 231. P~OTO-FILE module 226 is started by sign on module 225 in r~sponse to input from remote display termlnals 300. P~OTO-FILE 226 expect~ user commands: "SPH" (store photo);
"DPH" tdelete photo); or "PHO" (retrieve photo). Reque~ts of the u~er command input module 226 first prompts the user for a real e~tate property MLS li~ting number (herR~tRr "ll~ting number"), and then verifies the exi~t.ence of the listing as well as the existence of image~ stored in connection with the listing. Module 226 trQnsmits to/from dynamic regions in host RAM 2~4. Commands are passed between module~ 226, 231 ~ 1n~ RSX-llA
operating ~ystem "send bloc1c~ n wt 11 be ~, ,,~ .

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~88S16 under~tood by those ~killed in tlle art). A eingle file management module 231 move~ image data between the dynamically allocated memory areas and permanent image files.
In the preferred embodiment, several load modules 2~6 can execute concu~rently for several corresponding simultaneous users sharing host computer 200, but only a single image file manager 231 load module exist~. Since file manager 231 is the onLy module whlch 1~ capable of acce~sing image file~ 232 etored on disk 206, conflicting or inconsistent operations requested by different users on the same lmage files are prevented.
In re~ponse to an "add or delete" command, module 2~6 controls flle manager 231 to add image files to or delete image flles from the databa~e ~tored on disk 206. In the case of adding image files, blocks of digital data repreeenting an image are recelved by module 226 from the user and stored ln a dynamic area o R~M 204 (block 233). Eile manager 231 then accosse~ thi-q dynamic area of RAM, reads the image data it contain~, and stores the image data in a ~ile on di~k 206 ~block 232).
The permanent image file stored on disk 208 in the preferred embodiment are indexed RMS Eiles with ~lngle keys, the key in the preferred embodiment being a concatenation of a nine ch~racter 11st number; a ~ingls character imnge ~phnto) number; and a single character image (photo) eegment number.
Storing photos requ~re~ additional disk storage ~pace on ho~t comput~r hard diek 206 (eince photos are ~tored at the host, the diek mnn~. ~e Added to the PDP-ll host system). Elow muc}l n(l~itlonal ~ ---. ~ , ~.X8~35~i storage araa depends on the number of activ~
li~tings. The following can be used as a guideline for additional disk requirements:

2,400 photos 24 MB disk 4,000 photos 40 Ms disk -.
8,000 photos 80 MB disk 16,000 photos 160 MB disk 34,000 photos 340 MB disk 65,000 photos 800 MB disk File manager 231 also deletes image files from disk 206 in response to user requests passed to it through module 226.
Module 226 also allows users to retrieve image file~ previou~ly stored on disk 206. In response to a u~er command "PHO" and a user reque~t specif~i.ng a listing number and photo number designating an image file, module 227 passes that request to file manager 231 via a "send block" and then waits for the file manager module 231 to respond. File manager 231 reads the requested image file from disk 206 and stores it into a dynamic area of RAM 204 (block 235). The module 226 then reads the digital signals from the dynamic RAM area and transmits those signals to the requesting ~l~er Yia communications facility 208.

REMOTE_DISPLAY TERMINAL ARCHITECTURE

Referring once again to FIGURE 1, remote display ~erminal 300 in the preferr~ mbodiment includes a microcomputer 302 (e.q., An IBM XT or - . , , ., , -- . : - . , : . , . . :. . . . . . . .

~2~a~6 compatible), a color monitor 304, ancl an optional video source such as a video ca~sette recorder 306 and a~30ciated video camera 308 (thi~ optional video source and camera being used to transmit new i~ages to host computer 200 to be added to the image database). Microcomputer 302 in the preferred embodiment include~ a processor 310, an a~sociated "hard" disk 312, a random access memory 314, a modem 316, and a graphics card 318.
Remote computer 300 can thus be configured either to "capture" images (i.e., to convert video image~ to digital form and transmit the digitized image information to host comp~lter 200 for storage);
or to retrieve images (i.e., to retrieve selected image~ storad on the host comp~lter and display, print or store such image~). The "capture"
configuration i5 somewhat more expen~ive than the "retrie~e" configuration, so that in a typical real e~tate office it might be advantageous to have only one remote display terminal configured to "capture"
images, but provide several terminals capable of retrieving images.

Displav Terminal Ca~ture C _f guration Photo3 are digitized at di~play ~tation 300 and ~tored on the REAL-TRIEVE/PHOTO-TRIF.VE host ~ystem 200 in the preferred embodiment. The task of digitizing image~ can be done at t71e Real Estate Board office, and also by an individual user having a remote display terminal 300 e~uipped ~ follow~:
IBM PC-XT (or compatible) . VHS - Video Cas~ette R~corcler '.

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Graphlc 8 Card Video Camera (Color) Video Capture Card Video Capture S~tware PHOTO-TRIEVE Sotw~re .
With this di~play station configtlration, a user can digitize photo8 and transmit them to the PDP-ll hoqt system 300 system. In the preferred embodiment, photo storage i9 performed on an interactive basis as will be explained.
The video cassette recorder produces a video image which the graphics card 318 converts to digital signals in a con~entional manner. The digital image i9 stored in the IBM PC RAM memory 314. The photo is then displAyed in the uppsr left-hand ~uarter o the display monitor 30~ at a resolutlon of 128 x lOO pixels. FIGURES 5A-5C
show that the digitized image i8 displayed at the same resolution it was scanned at.
Once a photo is scanned and displayed on the monitor 304, it i~ available or storage on the PC-~T hard dislc 312 if desired. The actual storage required i~ about 12K per photo. (l28 dots x lOO
dots = l2,800.~ Conventional data compression routines are used in the preferred embodiment to reduce the data storage for a pho~.o to between 6K-8K.
When communication is est.~ hed between the ho~t 200 and the display station 30Q ~preferably, such CommuniCatiQn~ is established before digitizing of images has bequn) the displ~y ~t~tloo ~end~ the li~ting number, the establisllecl qrnpl~lcn transmis-qion mode and the compressed photo to the . ' : ,.
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ho~t. The graphics are stored by the host 200 as a ~eparate file from the text listing file. BecauRe the li~ting number is transmitted with each photo, new photos and changed pllotos are antomatically updated.
In somewhat more detail,~the capture configuration hardware for remote display terminal 300 in the preferred embodi~ent is a Zenith*PC model 241 with color graphics (FI~URE 1 bloclcs 310, 312, 314), an AT&T IC8 video digitizer board (block 318~, two Son~ KV1311 monitors (blocXs 304,322~ (a sin~la pointer can be u~ed if desired), a Magnavox*VR8278 video camera (block 308), and an optional printer.
The camera 308 and one of the monitors 304 are connected to the AT&T ICB board 318 for input and di~play of picture~. The other monitor 322 i~ used for text display of menus and TTY terminal communications from the PDP-ll ho~t. A graphical illustration of thi~ "capture" conEiguration i9 ~hown in FIGURE 3. FIGURE 4 is a ~chematic illustration of the rear panel of the FIGURE 3 p~oces~or 302.
The PC software includes TTY conventlonal terminal emulation routines. Provision i~ made for saving parameters for and accessing 15 different host systems. Once a serial asyncllronous connection i~ establlshed, the user iB in co7lver~Ational mode with the REAL-TRIEVE sign on mo~lnl~ 225 executlng on host system 200. REAL-TRIEVE 1~ a group of computation, da~abase input, dAtabase ~earch, and database di~play ~unctions acce~ed by ~pecl~ying the desired function at the malll pt ompt.
When the user wants to inp~lt fl plct~lre in the *Trade-mark ' . ' ' ` ; ' . . i , ~ , .- - , ,, . ~. :. . .
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21 63~23-267 databa~e, the store photo function (SPH) i9 reque~ted by entering tlle command "SP~ fter the host comp~ter 200 loads PIHOTO-FILE module 226 and display terminal 300 loads a corresponding "PHOTO-STORE" module (as is disc~l~sed in greater detail shortly), the host sen~s a special inquiry sequence to the display terminal and awaits a reply that indicate~ matching softwiare i~ executing on the display terminal 300. Then, the module 226 prompts the u~er for a listiny number. The user's response i~ verlfied against the MLS text database ~also maintained on the host system) and i9 re~ected if the requested listing does not exist.
Otherwise, the street address of the property as~ociated with the listing number is di~played to the user ~or possible visual cross-checlc. The photo database is then searched and the quantity and number ~1-16) of the exi~ting pictures (image files already stored on host computer disk 206) corre~ponding to the listing is also displayed. The user iB prompted for the number of the picture to be added. The u~er can add pictures in any order in the preferred embodiment, and picture~ are generally retrieved in numerically order (rather than in the order they are stored~. IE thAt picture number is not already stored, a special BeqUence iY ~ent to the remote data terminal 300 and both the ho~t computer and the remote data t~rm~nnl enter a blocked data transfer protocol wherein the terminal act as the "master" and the host acts as a "~lave". Th~ remote data terminal 300 ~l~o switches to a local capture men~l wh~l~ m~lntaining the protocol in an idling state.

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12885~6 At the local capture rnenu, the user places the picture to be captured in front of the video camera. The second monitor 30~ (see FIGURE 3) displays the image as it will be captured. The user may adjust the brightness, hue, and intensity of the picture via the remote data terminal 300 Iceyboard.
The camera i9 usad to ad~ust focus and frame the picture. When the live image is satisfactory, the user presses a single key on the remote terminal keyboard to complete the capture process. The image i~ frozen, reduced to a quarter screen size, and color mapped using modified AT&T routines and AT&T
graphics card 318 in the preferred embodiment. The image is then compressed using conventional image compression algorithms and sent block by block to the host computer 300. Each block i~ error checked (using CRC error checking routines and information -transmitted by the remote terminal with the image data) and stored by the host comp-lter module 227 in a dynamic area of host RAM 204.
When the entire picture has been received, central picture file manager 2~1 places the image in the picture database on disk 208 indexed by its li9t and photo number. The block protocol is terminated and a success or error message is displayed for the user.

, .. .~
.- ., . ~ . . :

~LZ~3a51~; ~
- 23 - 63~23-267 Display Tarminal Picture Retrieval Only Configuration Once the photos are stored on the PDP host sys-tem, they are then available for display at re-~ote terminals. Such images can be retrieved by remote display stations 300 having either the "capture" configuration o~ tne "retrieve only" configura-tion.
A conventional modem 316 is connec-ted to the communication port of -the display terminal processor 310. Each display station 300 initially operates as an ASCII terminal. As an ASCII terminal, the display station can access the normal text listing information. When "PHO" is entered as a function, a "mini-listing" consisting of 40 columns of text by 9 lines is sent by host 200 to the display terminal 300 (the contents of this "mini-listing" will be discussed in greater detail shortly).
Display terminal 300 and host 200 then enter the blocked data protocol with host 200 ac-ting as "master" and terminal 300 acting as "slave". Host 200 transmits data representing the image, and terminal 300 "paints" the color photo in 4 passes on its graphics screen in the preferred embodiment. When the photo is finished, -the normal "print full listing" is displayed on a background screen.
To view the background screen, a user presses -the F10 (or other "hot") key. By pressing F10 again, the user sees the color photo. To con-tinue, the user presses F10 to display the te~t screen where a main menu prompt is displayed.

r " ' ' ' ' ' , ' ' ' ' ~ ~ ' ' ~ ' , . ' ' ' ' , 12~38~

Transmission time for ima~es depends on the size of the photo and modem speed. The following table sets forth representative transmi~sion times for various modem speeds based on average photo size of 6K.
Speed _.Seconds 4~00 20 In somewhat more detail, display terminal 300 configured for "retrieve only" functions in the pre~erred embodiment includes a Zenith lSB PC with color graphics (blocks 310, 312, 314), an AT&T VDA
card (block 318), a Sony CPD-131 color monitor (block 304), and an optional Panasonic KXP~1091 printer in the preferred embodiment. Both the monitor 304 and the color graphics port are attached to the AT&T VDA card 318 90 that the monitor can display either text from the color graphics port or graphics from the AT~T card under software control (thus avoiding the expense of a second pointer).
The rsmote data terminal 300 software includes TTY terminal emulation routines. Provision is made for ~aving parameters for and accessing 15 different host systems. Once a serial connection is established, the user display termln~tl 300 is in conversational mode with the host REAL-TRIEVE system 200. When the user wants to retrieve a picture in the database, the photo function (P~O) i~
requested. After loading the mo~lle 226, the host computer 200 send~ a special inq~llry ~eque2lce and .. . . .

~288~;~6 awaits a reply that indicates matching ~oEtware is executing on the remote data terminal 300. Then the module 226 prompt~ the user for a listing number.
The user's response i9 verified against the text database and i8 rejected if the re~tested llsting is not found. Otherwise, host 200 sends the three portions of the photo listing -- brief text ("mini-listing"), picture, and full listing text --each delimited by a special sequence (as will be explained shortly).
At the remote data terminal 300, when the software receives the special start brief text sequence it ~witches the monitor from color graphics text to the VDA graphics mode. The mini-listing text is displayed on the lower half of the graphics screen. Then, as each block of the picture i8 received, it is painted on the upper left quadrant of the screen while the next block i9 being received. The full listing text following the picture is painted in the internal memory of color graphics text card 318, but the monitor 304 is left in VDA graphics mode. The user can use the k~yboard to switch between the two display modes. If additional pictures are available, the user ~ay r~quest host 200 to ~end them one at a time.
Additional functionality i8 provided at the remote data terminal 300 with ex~n~ton~ to the TTY
terminal emulation. A four pag~ buffer i~
maintained that permits the user to view text that has s~rolled off the screen. User3 can ~ave taxt in a file or print it as it is received on the communications link. The la~t r~c~v~d mlni-liRting text, photo, and full listing can ~l~o be added to a . - . :. ~
'- ~ ~ ' ' ~ . ,,' ' ';

- - ,, :
' ~ . .

~6 local database ~tored on terminal disk 312 if desired. In an off-line mode both the text and the photos that have been saved can be reviewed and printed.

USER DISPLAY TERMINAL EN_IRONMENT

The user intsrface includes two logical screens - a conversational ~creen and a graphics ~creen. In a dual monitor environment, the logical screens may actually be displayed on two separate monitors. In a single monitor environment, the user can flip back and forth between the two logical screens by pressing a "hot key" (e.g., F10).

Access by users to the functions which manipulate image files i~ controlled by the ~tandard function validation mask in a user's Terminal Control File. This is the same security mechanism used for all other online functions (e.g. add new listing) in the preferred embodiment.

(A) Retrievinq a Photo (PH03 To retrieve an image, the user connects to the Realtrieve online host system 200 ln the standard fashion. The MLS listings ar~ ~flrched for probable matche~ using the Search Listlng ~SL) function. The MLS nu~ber is used to dlsplay addltional information using the Print Li~ting (PL~ or Full Li~ting (FUL) functions. Once the selection~ hAv~ be~n narrowed a color photo can be displayed usin~ tl)~ Photo function (PHO) as ~hown: i :'.

.

- - -:

. : , : . . . ..
.. . . . . ..

~i 288S16 C--.~ _5a~ -5 '~

j i ! I

_____~ ____________~__~ _ _ .

A 'What Ara You' probe is sent to the uRer's di~play terminal 300 to verify that the display terminal has the appropriate photo display or :
capture capability. If the terminal does not respond to the probe (or respond~ incorrectly), the function i9 terminated. If the probe i~ ~uccessful, the user is prompted for the MLS number:
,.
Cor.ll~sa:~cA 1. Sc_ec3 G~ sc-e~ -.~ c;:? Fo I I~_~__~A-___~___ : I l l I '. ', I -~ '5_~-5 ;~ ? 850'~.~5 l I !
~`` Ij ' I I j :,, ~:The MLS number is validated by host ~ystem .:
200. Host system 200 then tr~n~mlts digital data representing the "Mini-Form" of the property listing text (40 columns by 9:lines) for dl~play on the ~:
bottom of the di~play terminal qraphics screen (as will be discussed shortly, the "minl-form" is a ~:
synopsis of the full property li~tlnq text which includes current information from tha MLS
;~ : :
~ .
:

. .

~l28~

database). ~ifferent colors are used to highlight the data portions of the Mini-~orm in the preferred embodiment:

c---- ~ _ _ ~ 9 8 . . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ y ..~ -? 3- '-.

`'- -::'-:' ?-'_8- S'2'^
A__ ~5s: 3:~ ~e i~c~_ 3e_:c-: 3 3a~3: ' . ~
- ' Cc--~-.~s~ ec:~ '~'^
s::--a~ cs:_s.
___________________________________ ___________________________________ Following this display, the digitized photo is transmitted for display in the upper left portion of tha graphics screen. Immediately after the photo is transmittad, the host system 300 automatically executes the "PFL" function to display a full listing on the conversational screen:

Con~ss~sa~~cr.a~ Sc:ee- ~ Sc~e~
_ _ __ _ _ _ _ _ _ _ ____ __________ ___ _ _ _ ______________ or.? P~O I I s~$~s~s~ss~s$$T
¦ T-5 ~ ~g --~--? r301~3 1 ¦ ~rs~lss$~s~$~ss !?-~ s~-5~^~o--n~c~ rS$~rS~s~s~s~S~
!iOt 0 5 }~C~: 93~;C0 ~:-2ss: 1~1 31~e Road 3 3~ .5 C--e.. s: E-Sc ~

5-~ L-~ IYpCS::-O.
__________ _ _ _ _ _ ~ ___________ ____ _ ___ _ _ __ _ _______ If multiple photos are stored for the listing, the user is asked whether additlonAI photo~ ~hould - . . . : : . . , , .:, . .

. . : . . -,, , , . , , , . - :

: ' , :, , ' :
' . ~ . , ' ' ' ' ' ' ' :' ~ 2813~16 be transmitted. In a single monitor environ~ent, the user will see this prompt when flip8 from the graphics screen to the conversational screen.
Subsequent photos are successively displayed in the upper left-hand ~ladrant of the graphics screen.
Note that the full listing data appears only after the first photo:

Ce.... :e-~a~ ~ 5~~se. G~~ ~s Se-e~-~ i ? ~ i ? ~ ~ ~ ? I ?
: ?;;; ii ? ? ? 3i ;
- 5- .. e --. --- e~? a 3 ~ 3 ~ ? ?T e~c~e ~ ? ~
S _ ~--.--, .. A ~ ? ? ~ ~ 3! T 3~ ? ~i i ? ~ T -3~^ C 3 ~-'ee: 58-:' c vc- ;-~ ~~e -.e~ ~_c e- ~ -25s ' '3 ~-ce :~e2A
i '3eA-:c-s: 3 32- 5 1;3 C:=e .:s: __e, e dee~
5e~ -~ e ., ex.ee~
_ _ _ _ _----When no more photos remain, the user is prompted for the next MLS number and the process repeat~. The user can "escape" to the "function level" at any time a~ shown:
Co~qe~2i_'c~ Sc~i G-a~ se:e-.n ______ __ _________ ________ _ ________________ ~ c'~io~? ~::0 1 ¦ T ~ $ $ ? ~ 4 . ? ? $ ~ i ~
¦ ~s' ir.s ~ ? 8'01CS5 ¦ ¦ 'T?$ F~:~ $T?~ ¦
T T T T ~ T T T T T T $ 3~ T T
P~, ll~t g ~ e ~ __on ¦ ¦ ~ T $ T$ ., ~ . $ ? ?T T $ I .
¦ ISo y'cu ~ t '~:e ~e:c ph~to? ~S I I Y -5T 85010~C P-iC~ 95500 ;~-es~ lz;ce ~o~d ~sti::g .o~ ? G5~ I 1 3e_ecas: 3 3a~u: l.-~:ac'icn? I 1 5-C-~ eY,eos~
_~________ .________~__ _ _____ , (B) Addina a Photo ~SPH~

. ~ , - :
. . . . . .
~ . .

:

~ ~8~35~

The process of adding a new photo to the database follows a similar format using tne two logical screens. Once again, the user gains access to the Realtrieve online host system 200 and invokes the Add tstore) Photo function (SPH) as shown:

C~ e-~ ' 5_~oe. 5~ ^s '^~se.

:

A 'What Are You ?' probe is sent to the user'~

terminal 300 to verify that the display terminal has graphics capture capability. The terminal 300 responds to this probe with display terminal profile information indicating whether the terminal has capture capability. If the terminal doe~ not respond to the probe tor responds incorrectly), the function is terminated. If the probe is successful tha u~9r i ~ prompted or the Ml.S nl~mber:

`:

~ ~sa~

Co.~ 'c-.a1 SC-9Q.~ G~-'~'cs Sc~een ______ .__~_________________________ ____ _____________________________ c-.? ,.~--.~--:e:? 850~

I

1 , ____________ _ _____ __ __________ __ _ ____ _ ________ _________ Host 200 determines whether the re~uested listing number i5 stored on host disk 206 in the MLS
database before a photo can be added. The address of the listing is then read from the MLS database stored on disk 206 by host 200, transmitted from the host to display terminal 300, and displayed for verification by the di~play terminal. Any information about existing photos i3 also shown.
The user i9 then asked to assign a photo number. If the photo number chosen already exists, the previous photo i9 replaced. Otherwise, the new photo is added to the database. The first photo i~ normally assigned a photo number of one ~1). A photo number of zero will cancel to process and return to the 'Li~ting number?' prompt.
The ollowing shows the text and graphic~
screen~ during the exchange of information set forth above.

.

.

. :

~ 2~385~;

C~ e_5a ':-.a 5__9~ ''--__5 5_-"~3 _ _ __ _ _ ___ _ _ _ _ _ _ __ _ _ _ __ _ _ -- __ _ _ __ _ _ _ _ .. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ __ _ __ _ __ _ _ _ _ _ _ .. -_-:-.. ? ~- :
' 5~ ' ..-, .. -~ a_ ? 3 _ ~
! ~ags: a-~:v~ e.
~e:a ~ .^s c.. ' ~'~c.: ..~' e-?:
!
I j ; .
I
__ _____________________ ________ ___ ____________________________ At this point, control is turned over to the display terminal 300 to scan the photo (i.e., the terminal becomes the "master" and the host becomes the "slave"). When the photo has been successfully scanned and the resulting digital data signals have been data-compressed using conventional digital data reduction techniques, the data is transmitted to the host 200 and added to the photo database stored on disk 206. Any errors will be displayed on the display terminal conversational screen. If the proce~s is successful, a positive acknowledgement will be displayed as shown:

CorlvQ~Ll:i4-a~. Sc:-a2 C:a.. !:lcs Sc~
¦ ~dtL~I~s. 8051 ~--y7and Av~!. ¦ ï TTTT~TTiTTTT~.~
~,.i~e 7~ O p~:oto OSI r~ sca~ TT~
I t-' ~'-o.o ¦ ~--0~ ^e_? 1 ¦ ¦ TTT~i7~Tt~TT /3 T r T '/ ;~ T T T T T ~ ~ ~ Y ~
y 9 ~r.s co.:v~t~ o~ ~>
L~o~o -l v2g s-lccess~ll~r 2d 'ed.
! Lis:~s.-.~:~-?

A s~cond photo for the same list1nq t~ ~dded by entering the MLS number, checktng th~ v~lidation ~ ~l38516 information and then specifyin~ a new photo number as shown:

- 5~ .. _e-? .~~,~ ,, ~~~~~~~~~----A _ _ i 5 5 ~ _ ' . _ A a .
~:--a c~-e- s,: c.. ''~
~' a-a ..~~~e~?

. i ' I j :
___________________________________ _________.. -________________________ The second photo is scanned and transmitted. A -positive acknowledgement is received. If there are no more photos to be added the user escapes to the ~ -'Function?' prompt as shown: .

Co~ve~sa~ 'o~al Sc-~ G-~oh~cs Sc-ee TT~$4~T ~T$T~ ~'$$
~'-c:o _~e:? 2 II .$' scar-e~ ~$~
$ . ,~o ~.3 2 ~ ~ T
<~ ~-.y sca~ canva s~~'cn ~ I I TTTT~T$~$TT$$
$~ $~.
i?'~o~a 2 ~ras s..c~55'~'1y 7~C~
~-' 5_~.g ..12~? ~_SC>
~-c_~ c3? 7 HOST ENVIRONMENT

As mentioned previously, the Phototrieve product exi~,ts on host system 200 ~,~ two RSX-llM
task images.

,. .
, -.. , , , . .~ , . . . . . .

, .' . .
.

1'~8~516 These are:

1) PHOTO-TO-FILE Module 226 Transmit~ a photo from a temporary sequential photo file over a dial up line to the remote user, receives a photo file from a remote user over .. . .
a dial-up line and stores it in a dynamic region, and/or deletes a previously stored specific photo; and 2~ PFM - Photo File Manager 231 Adds photos to the Photo File from a dynamic region copies photos from the photo file to a dynamic region, or delete~ photos in the photo file on requests from SPH module 226 tran~mitted via "send blocks.".

PHOTO-FILE module 226 is activated by the SIGNON task in response to the PHO, SPH, or DPH
commands. PFM 231 is active all the time but ls stopped waiting for a send packet from task 226.
When module 226 requires the services of PFM 231, it issues a send block and then "un tops" PFM --after which it attempts to read a return send block. On completion of the requested service, PFM task 231 issues a send block ~nd ln turn "unstops" the requestor task. T~le operation of "send-block" on PDP-ll system~ ~ R w~ll understood :;
by those ~killed in the art. ~
The operation of these program~ in response to ~ :
the various user commands is descrlb~d in the ~ections below.

,, ~, , : .
., ~. ' ' ' . . .- .
. - . . , '.' ,' :'. ', ', - '~ . '' ~ ' , ' : .
... . . . . . .

~ 2~38S~6 Displav Photo Command (PHO~

This command is used to retrieve a specified photo from the host photo file. When the command i~
entered, the SIGNON task activatas the PHOTO-FILE
task 226. The following sequence of steps i9 then performed by host 200:

* "PHO" - Retrieve Photo Task, module 226 - Send identification req~lest ESC DIS escape se~ence to user terminal.
- If ESC-PC escape sequence response not received, print error message on user terminal and return to "sign-on" to issue "FUNCTION"
prompt.
- Prompt user for list number.
- Verify exlstence of listing in master fila.
- Build 'inquire' send block containing the list number and send it to PFM module 231.
- Wait for response send block from P~M.

* PFM - Photo File Manager Task 231 - Receive send block and decodes 'inquire' command.
- Get list number from send block, and searches photo file for all photos for the specified listing.
! Build a photo mask with blt~ ~et -~
corresponding to each exlstlng photo.
-Returns send block to module 226.

* P~IO - Retrieve Photo Task, mod-llo 226 - Receive the send block ~nd 0x~mlne photo mask ,, ~ . , ~ 385~i - If no photos exist:
o Send message to that effect to the user terminal o Return to the 'list number' prompt.
- Send message to user terminal indicating which photo numbers e!xist in the photo file.
- Send ESC PML escape seq~ence to signal start of mini-listiny.
- Generate mini-listing and transmit it to display terminal with color control codes embedded in the text.
- Send ESC-ASY escape sequence to signal return to asynchronous mode.
- Build a 'get' send block requesting the irst photo - Send the send block to PFM

* PEM - Photo File Manager 231 - Receive the send block and decode 'get' command.
- Get specified photo data from file and store it in a dynamic region 235.
- Return send block to module 226 with dynamic region identifier in it.

* PHO - Retrieve Photo Ta~k, module 226 - Attache to dynamic region - Send E5C PHO escape seq~nc~ to signal blockad protocol.
- Enter the protocol mode a-~ "master" and tran~mit the photo data to the dlsplay terminal 300 (which acts a~ ve."
- Send ESC ASY escape sequenc~ to slgnal :, . . . . . . .

.

: ' : ~-' : ' , : ~ . ' - . . ' ~1 ~88~

return to asynchronous mode.
- Delete the dynamic region 235.
- Automatically execute "PFL" function to print the listing data. (Note that this occurs only after the first photo is transmitted) - If any more photos exist o Ask user if next photo should be displayed o If so, build 'get' send block requesting next photo from PFM and repeat the sequence.
o If not, return to 'list number' prompt. -[esc] charactar Add Photo Command (SPH) This command i~ entered to transmit a photo from thedisplay terminal 300 to the host 200 and add it to the photo database. When the command i5 entered, the SIGNON task module 225 activates the P~OTO-FILE task module ~26. The following sequence of steps are then performed:

* DPH - Add Photo Task, module 226 - Decode 'add' command from SIGNON
- Send identification request ESC CAP escape se~uence to user terminal.
- If not ES~-PC escape sequence response o Print error message on n~r t~rminal and return to SIGNON to i~sue 'F~lnctlon' prompt.
- Bu:Lld 'inqulre' send block containing the list number and send it to PFM 231.
-Wait for re ponse send block from PFM module .

. , . . . ~ . .

.
.
: : ~

lzass~6 .

* PFM - Photo File Manager Task 231 --Receive send block and decodes 'inquire' command.
- Get list number from send blocX and ~earch disk 208 for all photos for the ~pecified listing. - -- Build a photo mask with bit~ set corresponding to each existing photo.
- Return send block to module 226.

* DPH - Add Photo Task, module 226 - Receive the ~end block and examine photo mask - Send message to user terminal indicating the numbers of all existing photos.
- Ask user terminal for number of photo to be added or replaced.
o If the number entered is the number of an already existing photo, the existing one will be replaced.
o If the number entered does not already axist, a new photo will be added.
- Send ESC-APH escape sequence to signal blocked data protocol to transmit photo from di~play terminal to host.
- Send 11 character photo identifier - nine character list number plus 2 ASCII character photo number (decimal).
- Enter protocol as "slave" Ftnd receive the photo data.
- Send ESC-ASY escape seq~tance to ~ignal return to a~ynchronous mode.
- On comple-tion of photo datA tr~n~fer, build a send block containing a region ld~ntifier for . , : ` , :,, ~ ;288S~6 the dynamic region.
- If photo number already exi~ts, put 'replace' command in Rend bLock.
- If photo number is new, put 'add' command in send block.
- Send block to PFM module 231 * PFM - Photo File Manager 231 - Recei~e the send block and decode command.
- If 'replace' command o Delete the existing photo from photo file.
- If 'add' or 'replace' command o Add the new photo file to disk 208 database.
- Return send block to module 226 with success status.

* DPH - Add Photo Task, module 226 - Delete the dynamic region 233.
- Print success or fail message on user terminal depending on status returned from PFM
231.
- Return to 'list number' prompt.
- User returns to 'function' prompt by typing [esc] character.

. . , - : . : .. . : .
,. . .

.. . . . . . .
- . - , . . ,. . ~ ~ : . : .

.:, . ,: - ~

8851~

Delete Photo~Command ~_Hl This command i~ entered to delete a specifi~d photo from the host photo file database stored on disk 208. When host computer 200 receives the command DPH, the SICNON task 225 activa-tes the task module 226. The following sequence of steps are then performed by host computer 200.

* DPH - Delete Photo Task, module 226 - Decode 'delete' command from SIGNON
- S~nd identification request ESC CAP escape sequence to user terminal.
- If not ESC-PC escape se~lence response o Print error message on user terminal and return to SIGNON ta~k 225 to issue function' prompt.
- Build 'inguire' send block containing the list number and send it to PFM module 231.
- Wait for response send block from PFM 231 * PFM - Photo File Manager Ta~k 231 - Receive send block and decodes 'inquire' command.
- Get list number from send block and searches photo fi~le for all photo~ ~or the specified listing.
- Build a photo mask with b~t~ set corresponding to each exist~n~ photo.
- Return send block to module 226.

* DP~ - Delete Photo Task 226 - Receive the send blocX and ex~min~ photo mask -, . . ~ - - . : .

~2~51~

~1 - If no photos exist o Send massage to that effect to the u~er terminal o Return to the 'list number' prompt.
Send message to user terminal indicating which photo numbers exist in the photo file.
Prompt user for number of photo to delete.
Build a 'delete' send block with the specified photo number.
Send send block to PFM 231 * PFM - Photo File Manager 231 Receive the send block and decode 'delete' command.
Delete the existing photo from disk 208.
Return ~end block to module 226 with ~tatus.

* DPH - Delete Photo Task, module 226 Print 3uccess or fail me~sage to user terminal depending on status from PFM module 231.
If any more photos exist o Prompt u~er terminal or number of next photo to delete o If number entered, loop back to build 'delete' send block and repe~t sequence.
o If either [ESC] or [CRI only entered return to 'list number' prompt.
U er returns to 'function' prompt by typing [ESC] character.

C _ ICATIONS BET~E~N ~ODUL~S 226, 231 Communications between PHOTO-FILE module 226 , . ~ . -: . . . . .

.

85~

and PFM module 231 are via 13 word "send blocks."
When module 226 wishes to access the photo file manager module 231 services to obtain or store a photo (ima~e file), it notifies PFM 231 of it's requ~sts via a send block. After completion o the ~ .
service, PFM 231 returns a send.block to rnodule 226 with the requested data, or in the case of a photo, with the file id of an imaqe file.
Communications of command in function between PFM 231 and module 226 in accordance with the following send block format:
:
:,.
Send Block Format :

# BYtes Definition 2 Command ~explained below) 2 Status (Complete Status) g 9 Char List No (List and photo number to be stored or retrieved) 1 Photo No.
2 Photo Mask t~lag~ present photo~) 4 Four byte (R~gion Identifier) Region id g Unu~ed 2 Two byte TID (T~rmtn~l ID) :

. ' ~ ~8~3Sl~

Commands in first field are selected from khe following:
` :
* ADD Add a photo to the photo file * DELETE ~elete a photo from the photo file * REPLACE Replace an existing photo in the file * INQUIRE Search for all photos for a listing * GET Retrieve a photo from the file * NEXT Return next list number for which photos exist in the photo file.

PHOTO FILE FORMAT

The photo file used in the preferred embodiment is an Indexed RMS variable length record file with a single key and a bucket size of lk - 2k bytes. The data representin~ each image is divided into one or more photo segments (records), each of which is sized to fit into a 'bucXet' of the RMS file --the~e segmentq corresponding to the line~ of data packets tran~mitted in blocked data protocol. Each photo can have a maximum length o 254 segments.
The file key used in the preferred embodiment i3 an eleven character field consi~ting of a nine - character list number, a one cll~r~cter photo number, ; and ona character photo segment n~mb~r. The list number is the MLS listing numb~r of the property corresponding to the image. The photo number is an arbitrary value between 1 and 16 which i~ assigned by the user when the photo i 9 submltt~d for storage. Once the photo number 1~ RR~lgned, it cannot be changed in the preferr~ od`lment.

: ,,, . :.
- , . . .
-. :, ., , . :
.

~ ~88~i~6 4~

Photo~ are always stored in the photo file in order of increasing photo number. Photos may be retrieved by photo number, or they may be retrieved seguentially in order of photo number. In the latter case, the photo number affects the order of retrieval of photos from the file. The se~ment number portion of the record key is one (1) for -the fir~t segment of each photo and is incremented for each photo segment. This method provides each record (photo segment) with a unique key.
Each record, or segment, of the photo file has the key field described above at the beginning of the file record header before it is written to the file. The record header is removed on retrieval before transmission of the photo to the display terminal.
FIGURE 7 i~ a schematic diagram of a typical image file record format.

P~OTO-FILE MAINTEN~NCE

A photo deletion utility task (which may be run periodlcally via an "MCR" command issued on host computer 200) scans the photo file and compare list numbers found there with list numbers contained in the master list file. Any photo~ for li~tings which do not appear in the master 11st flle are automatically deleted from the photo file. This utility uses PFM module 231 services for all access to the photo file -- since in the preferred embodiment, access to im~ge file3 ~tored on disk 208 ls ~trictly limited to the PFM mod~ ln order to prevent conflicting operation~ rom b~lng performed - , - , - , . , ~

....
- ~ : . ' , -~ 288S~6 on individual files -- and also to permit this routine maintenance utility to be run on line without affecting normal p]hoto file access.
As list numbers and their accompanying photos are deleted, the di~k 208 space remains dedicated to original list numbers (keyR) while at the same time new list photos with higher list numbers will cause files to be extended. Files therefore need to be compressed periodically to ensure that all images relating to a particular listing are stored contiguously on disk 208 (and thereby decrease disk access time). File compression can be performed using standard host RMS operating system utilities to compress the file. In order to compress files, unused disk space equal to the size of the input files are required on the di~k. User access to the photo files is denied by the host software while this compression process is in progress.
:

., , ~; . : ' ~: . ' ' . . . . :
..

12~3~35~6 MINI-LISTING

The 'Mini-Listing' described in thLs section refers to an abbreviated version.of the Print Full Listing (PFL) used for display on the color graphics terminals having a 40 column output restriction.
Mini-lis-tings have a 9 line limit -- allowing then to be displayed concurrently with the color photoq.
The first line of the Mini-Li~ting in the preferred embodiment displays the current list price (LP), selling price (SP) and li~ting status (5T
e.g., NEW, ACTV, SOLD) taken from the Master Multiple listing service record corresponding to the property of interest. This is similar to the current Print Eull Listing function.
Mini-Listing formats will be defined using the "EasyEntry" forms editor (EASYED) as is currently done for the full listing forms. An additional definition file defines a subset of fields to be extracted from the full listing record for display in the Mini-Listing~
When the Mini-Listing is displayed as part of the photo retrieval function (P~O), additional color control characters are inserted in tlle output stream in the praerred embodiment, ~llowtng the variable data and the background form to b~ hlghlighted in different colors.
The Mini-Listing is displayed as 2art of the photo retrieval function (PHO). The QXi 8ting Print Full List:Lng shared code already In ll~o by REAL-TRIEVE to generate full li8tlng format~ is .

. :. -: - :
~ '' . ~ .' ' -: ,:; . .

~2~3851~

~7 .

used, with the following modifications, for generation of mini listing formats:

o A custom PE~INTLIST definition (with a 40 column limit) is used for the first line to display the li~t price (LP), selling price (SP) and listing status (STJ.

o Special color control code~ are inserted in the output stream. The ~-control character COLOR BKGRND
precedes each background or fixed portion of the text. The control character COLOR DATA precede~ each data or variable portion of the text.

The existing code for 'vectored data' is used to selectively display portions of the full listing record.
This allows selection of any incorporation of the selected fieIds lnto the mini listing format in any desired order rather than displaying the data as a se~lential stream (as is done for PFL).

PROTOCOL OF COMMUNICATIONS ~ETWEEN THE HOST
AND THE D I S P LAY TERM I NA L

Comm~nication between the ho~t ~omputer 200 and the display terminal 300 occura ~t two l~el9 -:

3851~

the command level and the data transmission level.All user commandY and response messaqes from the host 200 occur at the commiand level. Photo data transmission occurs at the data transmission level.
To move from the command level to the data transmission le~el, one of two escape sequences - to indicate direction of pending data transfer - is transmitted by the host 200 to the display terminal 300. On completion of the photo data transmission, and following the normal exit from the transmission level protocol, an additional escape sequence is transmitted by the host to insure that both sides of the line remain in sync - that is, that both the host and the display terminal recognize the return to command level protocol.~ Each of the e~cape sequences is transmitted by the host to the display terminal in the preferred embodiment -- none are transmitted by the terminal to the host.
The command level protocol used in the preferred embodiment is a conventional asynchronous terminal character protocol. Image data transmission protocol is ~ased on the ANSI X3.28 blocked data protocol.
After a u~er has inputted a photo command at a display terminal 300, and when the picture data is to be transmitted, the host 200 ~ends one of two escape sequences ~to indicate phot~ transmission or reception) to the display termlnAI dlrecting it to enter the blocked data protocol. When picture data transmi sion i~ completed, the blocked data prococol is exitedl as provided ~or in the protocol, after which the host send~ a 'protocol ~x1t' escape sequence to insure that both sidR~ reco~nlze the -~ ,~ . , - . , ' ' ' ~ . .. .

~28851Ç~

return to the command Level.
Whi le the bloclced da~a protocol u~ed by the preferred embodiment is based on the A~lSI X3.28 protocol, there are ~ome significant difEerenc~s.
For example, the two bytes of checksum data are never allowed to be control character codes in the preferrad embodiment. I the low order 7 bi ts of either checksum byte represent any control characters (i.e., less then 40 octal1, an octal 100 is ORed with the byte both at the tran~mitting ~ide before transmi~sion of tlle CRC and at the receiving side after computation of the CRC and before the receiver checks CRC. This convention prevents CRC
error checking infor~ation from being confused with reserved control character information.
An additional restriction placed on the transm1tted data is that appearance of the Eollowing control characters in the data stream must be re~tricted.

~ S,Q,F- Control S, Q or E (octal 23, 21, 05)- DC3 and DCl Thece characters are reserved to allow for flow control by any ~tatu~ m~ltiplexers w1licll may be in ~he data path. Note that thi~ conve~tion is ob~erved without regard to the Illqi~ order bits of eight bit character~. That 1~ ch chnracter really represent~ two eight bit vnl-~es. For example, "control S" implies both 023 and 223 octal.

~ P - Control P (octAl 20~ - DLF.

, ., ~ ~385~6 For efficiency of the host 200 input, this character should only appear as a part of the TSTX and TETX
(Transparent start and end of text~ sequence~. This character causes termination of a data read request by the host 200. Thus, appearance of this character in the binary data stream transmitted from the display terminal 300 to the host 200 causes the termination and reissuance o a read request, resulting in several reads being issued by the host to read a single block of data. While ~uch repeated read requests do not seriously disrupt system operation, they do decrease the efficiency with which the host 200 handles input signals and therefore decrease overall system throughput.

* Display Terminal Escape Character The character selected by the di~play terminal 300 to escape or flag the encoding of the above chara ters in the data must itself, of course, be escaped. That is, if 'esc' is the escape character~
selected, then an 'esc' in the data must be transmitted a~ 'esc' 'esc'.

The above characters, wherever they appear ln t~e photo data, must be encoded by the display terminal 300 transmission of photo data to the host and be decoded again by the dl~pl~y terminal on retrieval of the data again for d1 splay. The method of encoding and decoding these character~
entirely at the discretion of the dl~plAy terminal software since they are treated tr~n~p~rently by the host 200 - that is, they are ~tor~d ln the photo , . ... . . . .

-. . . ~ , - , .
, . . , .: , : . . ~ . -.

~85~.~

file and returned back to the display terminal 300 exa~tly as originally encoded by -the display terminal.

Storage of encoded data without interpretation by the host implie~ that on retrieval of the data by the ~ame or different di~p:Lay terminal 300, it is possible that the escape character used to flay the encoded character - which should not be the DLE
character - could be the last character in one record and the encoded character itself may be the first character in the next record.

An exemplary communication between host 200 and a display terminal 300 using -the ANSI X3.28 protocol i8 described pictorially a~ follows.

Host Di3Play Terminal l) Host is ready to enter protocol to transmit/receive photo data [ESC] 'sequence' ~
~here 'sequence' is:

ESC SPH to receive data (ca~1sQ~ th~ di~play termlnal to become the master 1n th~ following exchanges), or .
ESC PH0 to transmit data - (causes the ho~t to become the "ma~ter1' in the followln~ exchanges).

-~ 2~3~3S~6 2) Connect Pha~7e Master S ave ENQ ~~~~~~~ -~------ ACKO
:

3~ Data Transmission - The following sequence of 'Data Packet' followed by 'ACKx' response is repeated until all data has been transmitted. ACKO and ACKl : are alternated on SUcceF7sive packets to allow the master to detect a missed packet.

Ma~ter Sl~ve Data Packet ------~

~------ ACK1/ACKO

- 'Data Packet' ha~ the followin7~ format in the pre~erred embodiment:
IDLE~ ISTXI [1-256 data character~j lDLE
¦FTX3 [2 byte C~C
where "DLE" is the "protocol escape7' ch~r~ct~7r, "STX"
is the start of the XE (hereafter, "ETX" 1~ th~

~.

- ~ . , . ~ ~ , , . : , - `: .
. .

~:8~3S~6 "end of text" character, and CPC is checksum data.

In the event the receiving unlt detects a CRC
error in the received data, the "slave" re~ponds with 'NAK' tnot acknowledga) instead of 'ACKx' and tne "master" retransmits the incorrectly received biock. Provision is also made for the "slave" to respond with an 'abort' response in which case the "master" stops transmittinq picture data, exits the blocked data protocol, and returns to command level.

(4) Termination Phase Master Slave lDLE] lEOT] ~ -->

- On tran~mission by the master and reception by the slave of this end of transmission sequence, each returns to character asynchronous (command level~ protocol.

Host DisplaY Terminal ESC ASY ------~

- The following e~cape ~eqtl~n~e from ho3t 200 to di3play terminal 300 flags the 0nd of the blocked data protocol and the return to the asynchronou3 protocol.

MENU .AND COMMA~ STRUCTUR~

- . .
:' . . ' ' . ' ~ : ' . :
' : ' ' ~.2~ 35~6 System 100 has been designed to be a "uqer friendly" environment ~o make it easier for a user of remote display terminals 300 to perform image related tasks. ~ccordingly, system software is "menu driven" with menus organized in a hier~rchical structure. FIGURE 6 is a schematic diagram of the hierarchical user menu structure of the preferred embodiment. The following are detailed examples of the preferred embodiment menu formats and command options shown in FIGURE 6, along with a summary of the steps performed by system 100 in response to selection of menu options.

, : .: - . - , : .. ..

12~8~1~

- 55 - 63423~267 PROGRAM INITIALIZATION

Install printer driver from East Coast Software for graphics Install routines Erom Blaise for serial port interrupt handling Install clock and error interrupt handling routines using routines from Blaise -for interrupt replacement Set up memory buffer space using routines from Blaise for memory management Initialize AT&T VDA board using routines from AT&T for graphics Initialize text graphics adapter using routines from Blaise for screen management Setup the base communications and terminal parameters using default settings from the PTERM.CFG
parameter file on the drive in the directory where the program was found Display the main menu and accept user Routines for text dis-input using routines (pg 3) play use routines from Blaise that actually paint the screen;
routines for user input use routines from Blaise that actually retrieve the keystrokes ~J~
~I.,. ~

. . . . . . .

.
-, ': ' , ' . . ' .

3lX~385~6 USER INPVT SCREEN

User input screens are used The screen presents a prompt throughout the system where defining the type of input choices for a variable cannot required and a window sized to be presented sequentially the maximum charac-ters permitted and containing the current value of the prompted variable with the cursor placed at the end of that value; some vaxiables are restricted to text only input and others permit any 8 bit value generated by the keyboard;
3 special key sequences are supplied Cancel Exits the input screen leaving the value of the prompted vari-able set as it was when the screen was entered Backspace key Erase the previous character and back up the cursor Return Validate and set the variable to the value in the window FILE SELECTION SCREEN

File selection scxeèns are The screen presents a list of used throughout the system the file names with the current to let the user view and selection highlighted in reverse select from a number of names video; the selection is changed by moving the highlight with the cursor keys; various operations can be performed by selecting the appropriate function key as defined with that screen ~.

. i , : . .
.. . . .

85~ K

C1: N13111 Menu: lo~al _ .. . ..... . . . . .
F h.-.t .:,-T~r m 1: t r,, :~
r~ pyri~ht 1 ~a~ by M-:-:r~, Data Matla~rr,~t~t S-.~rvices Divi5ion :: F 1 ~ E ~; i t t .~ D~lS
~ F ~ at~ s~t l ~p CF8:~ F. ,rrnat dat~ di sk:
C F4 ::-~
C F5 ::

~:F7~ Di spl ay t~xt iF8~ l~ispl~y ph.~t4s CF~, Sel e.-t setup ** DEFAULT **
CF1~ Call th~ h~st cornput~r Pr~ss th~ appropriat~ functi4n k~ to make y~ ur sel~.-tion.
.. . . .

' ' -- t . ' ' .

- :, , . : , " . .: .
. :~,, ' ,. ,. ' ' , " ' ' : . ' : . - ' - , . . .

~38~16 Fl - EXi t to DOS
Pressing Fl returns your monitor screen to the DOS C> prompt.
F2 - Change setup Pressing F2 takes you to an input screen which asks you to enter a password. Only an authorized user can change the terminal and communications setup.
F3 - Format data disk Prassing F3 enables you to prepare a brand new floppy disk for use. ey pressing F3 you get a message to place a floppy disk in a designated drive (usually drive B). A floppy disk, once placed in the drivej is formatted for use by your computer. Use caution in formatting used floppy disks, as all files will be erased.
F7 - Display text Pressing F7 displays a menu that permits you to select a text file and display or print text that has been I -stored on your computer.
F8 - Display photos Pressing F8 displays a menu that permits you to select a photo file and display or print photos that haYe been stored on your computer.
F9 - Select setup Pressing F9 selects the setup for your terminal and communications that is used when F10 is pressed to contact your host computer.

F10 - Call the host computer ; Pressing F10 initiates steps which cause your computer to communicate ~ -with the host computer on which the Real-Trieve information system is available.

, .: ~. : , '. ' , . . .. . ..

- 59 - 63~23-267 MAIN MENU

Exit to DOS Reset AT&T VDA board using rou-tines from AT~T for graphics;
reset text board using routines from Blaise for screen manage-ment; restore original clock and error routines using routines from Blaise for interrupt management; free memory buffers using routines from Blaise for memory management Change setup Execu~e password checking with a user input screen prompting for the password; display communica-tions and terminal setup menu with current parameters and accep-t user input (pg ~) Format data disk Verify that data disk is not hard disk or program disk; call DOS format command using routine from Blaise for calling DOS
commands Display text Open default text file; display first text screen and accept user input (pg 7) Display photo Open default photo index file;
display user selection screen: :
~ith photo names and accept user input (pg 8) Select setup Recall next set of stored para- :
meters making them current Call host system Initialize the serial port using routines from Blaise for serial communications; place modem dialing prefix and telephone number in the output buffer;
display the on-line communica-tions screen and accept user input (pg 10) ,~ . -.
. ~
' ~L~885~i C2: System Communlcatlons & ~ermlnAI Setup: local System Communications ~ Terminal Setup <Fl> Exit to main menu <F2~ Change terminal setup <F3> Prefix string for autodial ..........
<F4> Phone number string for autodial ..........
<F5> Hangup string for autodial .......... ~.
<F6> Answerback string ** HIDDEN **
<F7> Com port number ~serial port) _ <F8> Speed (baud rate) ~................. .
<F9> Select setup ...................
<F10> Save communication~ setup ¦ -Press the appFopriate function key to make you selection. : ~

:

:

. .. ., . : - . . . .
. . . ~ . . -:
.
. . ~ .
:: - " ~ : ; ~ ~ ' -.

~235~

COMMUNICATIONS & TERMINAL SETUP MENU

Exit to main menu Display main menu and accept user input Change terminal setup Display terminal setup menu with ter-minal parameters and accept user input (pg 6) Prefix string for autodial Display user input screen prompting for modem setup commands and accept user input; set current prefix to user input Phone number string Display user input screen prompting for telephone number and accept user input; set current phone number to user input Hangup string for autodial Display user input screen prompting for modem hangup commands and accept user input; set current hangup to user input Answerback string Display user input screen without current value, prompting for new :
answerback and accept user input; set current answerback to user input Com port number Switch current port between port 1 or : 2 Speed Set current speed to next speed in cycle ~300, 1200, 2400, 4800, 9600) Select setup Recall next set of stored parameters making them current Save communications setup Display selection screen with names of all currently saved setups; the following functions are availableo Exit-Display communications and termi-nal setup menu Erase-Remove the highlighted entry and rewrite the PTERM.CFG file Default-mark the highlighted entry as the default one to use when the pro-gram starts and rewrite the PTERM.CFG
file .~ .

- ~ : . .' : . . , . : . ' .. . . ~

:- - . , ~ . .

385~

61a - 63423-267 Rename-display the user input screen prompting for a replacement name for the highlighted entry; rewrite the PTERM.CFG file Replace--take the current values and use them to replace the values of the highlighted entry; rewrite the PTERM.CFG file Add-display the use.r input screen prompting for a new name for an additional entry; rewrite the PTERM.CFG file :
":

,: ... . . . .

8~3S~6 C3: 5y tem Tem~lnal 5~tup: local System Terminal Setup <Fl> Exit to communications menu <F2> Separate photo monitor <F3> Printer port <F4> Printer type ................
<F5> Printed photo size <F6> Photo print sequence ........
<F7> Data:drive _ I .
<F8> Data path ........ 0 <F9~ Set password ............
<F10> Save terminal setup and exi~ : -Press the appropriate function key to mak~ your selection.

, " ~ . ' . ' ' : ' , : ' : ...... ' , - , ' - - . . .
. ..
. . - : ' ~ .,: .' : ' 3 28~

TERMINAL SETUP MENU

Exit to communications menu Redisplay communications and termi-nal setup menu with current para-meters and accept user input ~:
Separate graphics monitor Switch between yes or no 2nd moni-tor Printer port Cycle to next printer port (1, 2, Printer type Cycle to next printer type (as supported by driver from East Coast Software) ~:
Printed photo size Cycle to next photo size (1-9 as supported by driver from East Coast Software) Photo print sequence Display user input screen prompting ~ -for P-photo, B-brief text, L-full listing text, and F-form feed to specify which elements and sequence .
: are to be printed for the print photo command; set photo print :
sequence to user input Data drive Cycle to next data drive (A-F) for use when saving text or photos or .
when formatting a data disk :.
Data path Display user input screen prompting for a pathname to use when saving text or photos; set data path to user input Set password Display user input screen without previous value, prompting for the :~
password used to control access to the setup menus; set password to user input Save terminal setup and exit Save the current terminal setup and rewrite the PTERM.CFG file; displa~
the communications and terminal setup menu : . . : . . .
: "
. .
, ~ , . . .
.

38~;~l6 6~

C4: Dlsplay Text: local , Do you want th~ n~xt photo? ~y/n)~ N
LIST}NG NUM~ER~S)? 17773 Photos ~urr2ntly on ~ilæ: 1, 2, 3, 4, S
Phoeo 1 plottæd.

INFOR~ATION IS ~EEMED RELIA~LE ~UT NOT WARRANTED
<~< L-S73,500 S- ~
Add: WILDWOOD WEST, CHARLOTTE Ar~a 02 S ~3500 Sign Y MLS# 0017773 Diræction~ RTE 7 SDUTH, lST R AFTER WILDFLOWER FARM, lST LEFT, 7N~ HOUSE nN
Housæ slz~ 2~%~6 Styl~ RANCH
Lot s~.F 175 lA~- Dæ~d V. 41 P. S78 Ap~.Sq.Ft. 1300 Color 5REEN
Rms App~.S~. ~ 1 2 Rms Appx.52. 8 1 ~ Fin.~smS UNFIN Flr5 HWtlNLAID
LR 15XlF X ~a 1,1J2M~R X E5t.Ag~ 10l- Wall~ SR
DR 1~.5X10.7 X BdR 15.SX11.9 X Constr. WF Pch~eck 4X10.
Kit 13.3XS.6 X ~dR ll.SX12.gJO X Fnd.WI~ PC St.Win THERMAL
Kit w~ ROHF,DW,DSS,RE SdR 11.6XiO.~ X Siding ~ASONITE Fpl LR W/S ~SMT
Fr Roof AS Typ Hæat ELEC~WD
Gar: 7 Att~Dæt~Und ATT Tot.Rms 5 Tot.BdR 3 Wat~r COMM. HtWtr ELEC O~R
Ræmarks: RANGE,~ED, NEW. WS, WOOD, TV A~TEN Sewer SEPTIC G~s~Uil Co ,DRAPES ALL STAY. SS~T GOOD HGT FOR FINISHI DrvWy GRAVEL El~ct.Co GMP
NG,~UILT IN CHlNAt HW FLOORS,APPROX S100* Zoning RES
l~EXIT 3~PRT FILE ~>~GN FILE s~sa FILE a~lX2 PA6E 9>9UF lO>NXT PA' : . ' ~: ' - ' : .. ' ` ' ' , ..

~Z8~3S~.~

DISPLAY TEXT

Text screen Display the first screen~ul of text from the file RTERM.TXT on the data drive in the directory path specified in the terminal setup and copy it to the multi-page buffer that holds the last 96 lines displayed; the following functions are available:
EXIT Redisplay the main menu and accept user input PRT FILE Write each line of the file to the printer followed by a carriage return and line feed BGN FILE Restart the display at the beginning of the file SEL FILE Display a user selection screen with all the .TXT file names on the data drive in the directory path specified in the terminal setup; let the user select the following functions:
Cancel-redisplay the main menu and accept user input Erase-delete the highlighted file and redisplay remaining file names Use-display the first screenful of text from the highlighted file on the data drive in the directory path specified in the terminal setup and copy it to the multi-page buffer 1/2 PAGE Display the next 12 lines of text on the screen and copy them to the multi-page buffer BUF Permit the use of the cursor keys to display the lines saved in the multi-page buffer and the cancel function to redisplay the last 24 lines NXT PAGE Display the next 24 lines of text on the screen and copy them to the multi-page buffer ;~, . , ... . , ~ . . . .
- . . ~ ~ :
',. . ~ ' ' '~ ' ' ' :~.' . . " ' ' " , " ' .

~as~

CS: Select T~xt Flle: local PTE~
MQORETXT

Us~ curs~3r k~ys t~ choose ~n ~xistinq ta~xt file.
~Fl~ Can,:~}
~F9> Erasæ highlis~hted t*xt file <F10~ Use his~hlighted text file Pr~ss the appropriate function k*y to mak~ y,-~ur s~ tion.
' .

., .

.. , . . ~ ~ , , . ~ ~ - : ` . ~ ' '` ' ' ' ' -: ' . . :
' . ,:

385~6 C6: Dl~pl~y E3u~ter I~FOPMATrON IS DEEMED PELIAhLE ~UT NOT WAFFANTED
~ L-$7~,~ S- ~
Add: WILDWOOD WEST "-HAPLOTTE Ar~a D~ $ 7350~ SiQrl Y ~LS~ 01~177~3 Dir~._tions F;TE 7 SOUTH, lST F~ AFTEfi WILDFLOWEF; FAR~, lST LEFT, 'ND HOUSE ON
LEFT H.-us: si~ 8X~6 Styl~ F~ANOH
Lot s-.F L~S lA~- De~d V. 41 P. 5-S Ap~.Sq.Ft. 13C~ ol.~r 1~F.EEN
Fn~s App~.S_. ~ 1 ' Fn~s App~;.S~ Fin.~s~.t UNFIN Flrs HWXINLAID
LF. lSXlS X ~a l,1/~fi X Est.A~ lC1~- Walls S~
DF. l ~.SX1l:l.7 X ~dF lS.SX11.9 X O-nstr. WF P:hZD~-k 4X10 4 t';it 13.3X8.8 X ~dP 11.5Xl~.~JO X Fnd.Wls FO St.Win THEP~A;
t~it w~ POHF,DW,DSS,PE ~d~ 1l.6XlD.6 X Sidirl~ ~ASONITE Fpl LR W~S ~SMT
Fr ~.~o~ AS Typ t/~at ELECZWD
4ar: Att~D~tXUnd ATT Tot.~rns~5 T-~t.~d~ ~ Wat~r 1;0~ HtWtr ELE6 OXR
F~n~arks: PAN~E,PED, NEW. WS, WOOD, TV ANTEN S~w~r SEPTIO ~asXOil ~o ~DF~APES ALL STAY. ~S~T ~OOD HGT FaP FiNISHI DrvWy 13FAVEL - El~.t.Co 13~P
N13,8UILr IN fHINA, HW FLOO~S,AF'~OX $1DO~ Zonin~ F:ES

:: ' .:
: .
1~CANCEL Usæ cursor k-ys to ~ov~ forw~rd and b~cku~rd.

' .
~.

, . . . , .. : . . . .

. . .

~ ~8~35~

C7: Dl~pl~y Photo: local PHOTO-Us~ cursor k:~ys t4 cho,3s~ a ph.3t~.
CF1> Exit to main m~nu CF~ Eras~ hiQhli~hted photo CF3~ ~ark hi~hlighted pn~to f,~r m--~ving CF6~ Fhoto print CF7~ Display hi~hli~ht~d ph-3to <F8~ S~lect an,3ther photo file .<F~ Vi~w buff~r with ~ull listing <F10~ Switch to photo ., ' . ' ~ ' ', ' ,' ~ . ,' '' ' ' :

- 69 - 63~23 267 DISPLAY PHOTO

Photo selection screen Display a user selection screen with the names of the photos saved in the index file PTERM.PDX on the data drive in the directory path specified in -the terminal setup; the following func-tions are available: -Cancel Display the main menu and accept user input Erase Remove the highlighted entry from the index; delete the file with the data for the highlighted entry; rewrite the index file Mark photo Note the currently highlighted entry as marked; enable the move marked function; if the move marked photo function is not the next function selected, cancel -the mark and disable the move marked photo function Move marked photo Adjust the index pointers so that the marked entry is placed ahead of the highlighted entry in the display order of the index; display the new index order Print photo If a photo has been displayed, print the last photo displayed (using the printer driver from East Coast Soft-ware), brief text buffer, full text buffer, and form feeds as specified in the terminal setup Display photo Reads the file pointed to by the high-lighted entry into the photo bufer, brief text buffer, and full text buffer; switch the AT&T VDA board to graphics mode using a routine from AT&T; paint the brief text buEfer on the VDA board using routines to con-trol placement and routines from AT&T -i to actually paint the characters; pass -the photo buffer data to a routine from AT&T for decoding and painting on ~
: the graphics screen in alternating upper quadrants so that two photos are displayed simultaneously , : .

:
' ~ .

Select photo file Display a user selection screen with all the .PDX file names on the da-ta drive in the directory path specified in the terminal setup; let the user select the following functions;
Cancel-display the main menu and accept user input Erase-delete the highlighted index file and all photo data files pointed .
to by that index and redisplay remain-ing index file names Use-display a user selection screen with the names of the photos saved in the .PDX index file of the highlighted name on the data drive in the direct-ory path specified in the terminal setup View buffer Copy the contents of the full text buffer to the multi-page buffer; dis-play the last 24 lines of the multi-page buffer; permit the use of the cursor keys to display the lines in . .
the multi-page buffer and the cancel function to display the photo name user selection screen Print photo If a photo has been displayed, print the last photo displayed (using the East Coast Software printer driver), brief text buffer, full-text buffer, and form feeds as specified in the terminal setup Switch to photo Switch the AT~T VDA board to display graphics using a routine from AT~T;
while graphics are displayed keyboard~ :
~-~ input is disabled except for the PH
PRT (Print photo) and BUF (View buffer) functions plus a NEXT PHOTO
function that advances to the next index entry before executing the Dis-play photo function and a MENU func-tion that switches the AT&T board back to display the photo name user selec-tion screen using a routine from AT&T .
-:

:
.. ..... , , . , . . , . , , , - . . , . -- . . . ..

.-.
.

38~i16 C8: Select Photo Flle: loc~l PTEF t~l ~AF:E~

Use cursor keys t~- ~hoose atl existin~ photo fil~.
CF1 ~ ~an-:el - CFg~ Era~i~ hi~hli~hted photo ~
~F10~ Us~ hi ~hl i ~ht ed photo f i l e ~ress th~ apprc~priate futlction k~y t~ nnakæ your s~le~tic~

. : ~. . .. .

3 2~3516 - 72 - 634~3-267 ON-LINE CO~MUNICATIONS
Received communications The serial communications routines -from Blaise handle a received charac-ter by interrupting the current acti-vity and placing the character in the input buffer Keyboard input Hardware routines handle a keystroke by placing a scan code into a keyboard buffer Communications loop A routine alternately checks the received communications buffer and the keyboard buffer using routines from Blaise; communications are checked for special character sequences and if not found are displayed as text or the appropriate format control on -the screen and moved to the multi-page buffer that holds the last 96 lines received; keystrokes are checked for function key sequence and if not found are placed into an output buffer using a routine from Blaise - the serial communications routines from Blaise then send the character out the serial port Received special sequences x05 Place the current answerback string into the output buffer xlD x5B x43 Place the terminal type response string into the output buffer xlD x5B x4D Switch the AT&T VDA board to graphics mode using a routine from AT&T; paint all received characters on the VDA
board using routines to control placement and routines from AT&T to : actually paint the characters; place it in the brief text buffer ,- ,. :

. ~
' -:' :
.
~ . - . ~ ::

~.2885~6 xlD x5B x50 Switch the AT&T VDA board to graphics mode using a routine from AT&T; estab-lish ANSI 3.28 block protocol mode with the host system using the clock routine to control timing; receive each block from the host; error check the block; check for an end block protocol sequence, decode and paint each block on the graphics screen (upper left if immediately preceded by brief text, otherwise upper right)using a routine from AT&T; place it in the photo buEfer xlD x5B x50 Revert to processing received data as ordinary text xlD x5B x70 Process incoming data as ordinary text and also place it in the full text buffer xlD x5B x51 Place the password protecting the setup menus into the output buffer Keystroke function sequences EXIT Confirm that user wishes to exit;
close open files and turn off printer;
reset AT&T VDA card to display text using routine from AT&T; display main menu and accept user input HOLD If not currently locked, place XOFF in the output buffer and disable display of received characters If currently locked, place XON in the output buffer and enable the display of received characters :
:: TX PRT If not currently on, send a return to printer and as each line received is completed send it followed by a return and line feed to the printer If currently on, disable printing TX SAV If not currently on, open a .TXT file -on the data disk in the directory path specified by the terminal setup using the name specified by the TX NAM
:~ command or PTERM if none has been : -specified; as each line received is completed add it to the file If currently on, close the file ~ .

:

- : ' ,' . .. .: ` ' : . - , ~
- . . . . .

5~i TX NAM Display a file selection screen with all. current .TXT files on the data disk in the directory path speci-fied b~ the terminal setup; the following functions are available Cancel-clo not change the current selection Use highlighted - make the highlighted file the current file for text Name and use new-display a user input screen prompting for a new name for a file for saving text PH PRT If a photo has been received, print the last photo displayed (using the printer driver from East Coas-t Soft-ware), brief text buffer, full text buffer, and form feeds as specified in the terminal setup PH SAV If a photo has been received, display a user input screen prompting for a name for the photo; add the name entry to the index file on the data disk in the directory path specified by the terminal setup using the index file name specified by the PH NAM command or PTERM if none has been specified;
open a file on the data disk in the directory path specified by the termi-nal setup using the name specified by the TX NAM command or PTERM if none has been specified and a numeric ex-tension based on its place in the index; write the contents of the photo, brief text, and full text buffers to the file P~ NAM Display a file selection screen with all current .PDX files on the data disk in the directory path specified by the terminal setup; the following functions are available Cancel-do not change the current selection Use highlighted-make the highlighted file the current index file for photos Name and use new-display a user input screen prompting for a new name for an index file for saving photos ... i .
. `

- :. :. , : ~ . , , - . .

.
.

- 74a - 63~23-267 BUF Stop displaying received communica-tions; permit -the use of -the cursor keys to display the lines saved in the multi-page buffer and the cancel func-tion to redisplay the last screen and restart display oE received communica-tions PHO Switch the AT&T VDA board to display graphics using a routine from AT&T;
while graphics are displayed keyboard input is disabled except for -the PH
P~T, P~ SAV, PH NAM, and BUF functions plus a TXT function that switches the AT&T board back to display text using a routine from AT~T

.

, . . , , : ~-. ,- , i . . .. . .

. :. ..
.
. .

~.2~ ;16 '`9: Sel~ct Te%t Flle: on-llne F TEF.:M
11OOF.:ETXT

Us~ ._ursor k~ys to choos~ an existin~ t~xt fil~.
- CF1~ ~an- ~
CF~ Namæ and usæ n~w tæxt file CF10~ Us~ hiçlhlight~d l;~xt fil~ :
Pr~ss th~ appropriatæ func~ion key to makæ your selæ~ti~n.
- .................................................. :

;. ::

:. . . . . . . . .

C10: SeldCt Photo File: on-lln~

PTEF.~1 ~AF~

Us ~~ur or k~ys to choose a~ existins~ phot~ file.

CF-3~ Name and use new ph~to file CF10~ U~e hiçihlis~hted photo fil~
Press th~ appropriat~ ~unction k~y to n~ak~ y~ur~ ction.

.. .. . _ .

, , ,. : - ::. . - -: . .' ' .. ~ . ~ . .. , :,, . - . .. .

~L28~516 77 :

Real-Trleve Communlc2tloM~ Dl~pl~y 10/08/86 16:14:12 LINE#4 TERMINAL #0600 GREETINGS
WELCOME TO MOORE DATA'S REAL-TRIEYE ON-LINE SYSTEM
FUNCTION?
l>EXIT 2>HOLD 3>TX PRT 4>TX SAY 5>TX NAM 6>PH PRT 7>PN SAV 8>PH NAM 9>BUF lO>P~O
.. ..

''' ', ~,' ' ,'.," , '. - '' : ' ~

.. - ~ , : -.

35~

7~ 63423-267 DET~ILED DESCRIPTION OF STEPS _PERFORMED BY
~OST ~N~ DISPL~Y TERMINAL

FIGURES 8-26 are detailed schematic flow cllarts o steps performed by 1108t 200 ~nd display terminal 300 during operation in tlle i~aqe mode of the presently preferred exemplary embodiment of FIGURE 1 system 100. FIGURES 9-12 are detailed flow charts of the steps performed by display terminal 300 to retrieve i~ages pre~iously stored by host 200;
FIGURÆS 22-26 are detailed flow charts of steps performed by the display terminal to capture and ~tore images on the host; and FIGURES 13-21 are detailed flow charts oE step.q performed by the ho8t to receive and transmit image data to the display tsrminal.

TERMINAL IM~GE RETRIEV~L

Image retrieval routine ("PHOTO-TERM") 500 shown in FIGURE 8 i~ executed by display terminal 300 in responso to the command "P~O" inputted by the u~er. R~utine 500 requestR a particular image stored on host 200 and displays the image on display terminal monitor 304.
In response to data received ~rom the ho~t ~:
(block 502), th~ display tqrmillnl determine3 whether the recelved data i3 31mply texl: ~.o be displayed on the conversational screen or spec~al protocol data which must be interpreted (decision block 504]. If the received data is merely text to be displayed, display ~erminal 300 acts simpl.y ~ ~ TTY displAy terminal by displaying all legal cllar~cters on its ..
.

,~ . .

.:

35~

conversatlonal dlsplay screen (blocks 506, 508~. On the other hand, ~f a "protocol sequence" character (i.e., a special character) ha~ been received, display terminal 300 tests the significance of the recelved character.
If the received character~s~ indicate a request by host 200 for the display terminal identification (testad for by deçision block 510), the display terminal transmits the appropri~te ldentiflcation response saquence (block 512). If receivecl special characters indicate the beginning of a "mini-llst"
(declsion 513), display termin~l 300 "flips" monitor 304 to the imag~ graphics mode ~nd reserves a storage area within memory 314 in which to store the incoming data (block 514). As te~t data corresponding to the "mini~ tlllg" i9 recelved (block 516), dlsplay terminal 300 writes the received data to the graphics display and also to a taxt buffer area within RAM 314 (block 518).
Det~ction of a further "protocol sequence" character (deci0ion 520) cause~ display terminal 300 to cease treatlng received data as "mini~ t" data.
If the "protocol sequence" character(~) received by block 502 are not identification inquiry or start mlni-list characters, displ~y terminal 300 determines whether tlle receivqd character indlcates a full text listing in ~bollt to be tran~mitted (decision 521). I r ~ e llost 200 transmits the ull text listitlc3, display terminal 300 cloars a buffer in RAM 314 or ~Ise in ~toring the li~tlng (block 522), ~nd thell recelves the ull text data and writes same to the b~lfer (block~ 524, 526). Insertion of a "protocol ~q~l~nce" character . ,"~

. , , .
,. .: , . : .
- . , .
.

~, : . .: ,. .

~!.2885~

in the text (tested ~or by decision block 528) is used to stop display terminal 300 from storing full tè~t infor~nation and to determine what other command has been specified by host system 200.
I~ the special "protocol sequence" character received by ^
display terminal 300 is a character indicating a photo (image) is to be received, (tested for by decision block 530; this start photo character is -transmitted by host 200 in response to receipt by the host o~ the command "PHO" transmitted earlier by the dis-play terminal operating in the TT~ mode~, the display -terminal ~.
executes receive image routine 532 to receive an image to be ~.
. transmitted by the hostO
If the special character received by display terminal 300 is a "password" inquiry (tested ~or by decision block 534), the display terminal transmi-ts a predetermined password in re-: sponse to the character (decision block 536). Finally, i~ the received special character is a command to display terminal 300 to return to the serial asynchronous terminal made (as tested for by decision block 538), the display terminal closes any open data buf~ers (block 540) and rever-ts to the TTY mode to await received data at block 502.
FIGURE 9 is a schematic diagram of the received image routine 512 shown in FIGURE 8. This received image routine is executed by display terminal 300 to receive and display an image transmitted to it by host 200. Upon determining that image data -is to be transmitted, display terminal 300 initializes various storage areas and parameters it will use to receive the image . .
,, .
.:

: :. ;, . :, ., ' . -., ::

.
., : ~ ' ,: ~ . :

~.~885~

(block 5~0). ~or example, display terminal 300 clears buffers and other storage areas to be used to store the actual image data;
initializes buffer pointers which point to locations within those cleared buffers; initiali~es an activity timer (used in the pre-ferred embodiment to discon-tinue image receiving if too long a period of time has elapsed since da-ta was received from the hos-t);
initializes a "positive reply" counter to 0 (this counter is used to "toggle" values of received acknowledged signals transmitted by the display terminal to the host between "ACK0" and "ACKl"); and initializes a "level" state variable to 0 (as will be explained in connection with FIGURE 11, the "level" state variable is used by the display terminal to determine the type of information it is to expect next).
After initialization step has been performed, display terminal 300 executes the terminal "slave" select routine 502 shown in greater detail in FIGURE 10. In the preferred embodi-ment, the one of host display terminal 300 receiving image data ac-t as a "slave", while the transmitting unit acts as a "master".
When operating as a "slave", display terminal 300 simply receives blocks of digital data, acknowledges receipt of those blocks dur-ing periods when host 200 is not transmitting data, and wai-ts for the next block to be transmitted by host 200. In the preferred embodiment, the "slave" mode is entered by display terminal 300 upon receipt of special protocol characters from host 200, and may be exited by the display terminal only under certain circums-tances (e.g., an activity time-out, or a positive indication from the host that the display terminal is , - - . . . . .
, .

.

85~i ~2 63423-267 to return to the asynchrono~l~ receive mode).
Oper~titlg displ~y termillal 300 in the "slave" mode during times ho~t 200 is transmitting image data prevents the display terminal rom interr~lptj.ng the host and also insures that image data transmitted by the ho~t is received by the clispl~y termirlal.
Referring now more particularly to FIGURE 10, display terminal 300 te~ts whether new data has been received from t21e host ~deci~lion block 550). If no data has been received from the host, then the display terminal determines whetller A "reply enable"
flag has been ~et (deci~ion block 552). In the preferred embodiment, display terminal 300 is inhibited from transmitting anytlling to host 200 during period~ when the host is transmitting image data becau~e the display termin~l i8 a "slave" to the hostls transmission. In the preferred protocol, however, the display terminal 300 must acknowledges receipt of each and every block of image data transmitted by the host -- eitl~er with a "positive"
aclcnowLedge me3sa~e indicating correct receipt, or with a "require" negative acknowledge message requesting retransmi~s~ion of the last data block.
Accordingly, when display terminal 300 determines that it ha~ correctly (or incorrectly) received a block of image data, it set~ "reply enabl~"
flag to "remind" itsel tllat it. mll~t tra1ls~it an acknowledge (or not acknowledg~) me~age to 2105t 200 when the host stop~ transmitting data.
If displAy t~rminal 300 determines that its "reply enabl~" fla~ i8 set (deci.sion block 552), it resets thQ actlvity timer (block ~54) ~nd then determines whether the "~ser ~bort." ~ has been .~ ~ . .

, - . . : . :. .

. . . - ~ . . :, . . .
.
- : .,: ,:
-, : ' - . , .

~ 2~385~Çi ~3 63423-267 set. In the preferred embodiment, a ~l~er may abort receipt of an lmage at any time by depre~sillg a keyboard Xey sequence (e.q., CNTRL-BREAK).
However, just as the display terminal will not interrupt ho~t transmis~ion3 Witll an ac1cnowledgsment mes3age, the diRplay terminal 300 will also not immediately send a mes~age t~ tlle host indicating the u~er has requested tlle current image display oparation to be aborted, but instead transmits thl3 me3sage after the ho~t has fini~hed transmitting it~
current data block.
If display terminal 300 determines the "abort"
flag has been ~et (decision block 556), it transmits ~:
the abort message and al~o set~ a "protocol abort"
flag (~lock 55~) to "remind" itself that it ~hould return to the TTY asynchronou~ mode of operation.
On the other hand, i the user ha~ not requested an "abort", the reply whlch was "enabled" to be sent is now tran~mitted to the ho~t (block 560), and is then tested to determine whether it is a "po~itlve" or a "negative" acknowledge me~sage (deci~ion block 562~. If the r~ply was a "negative" acknowledge message li~t,("NAK") control returns to decision block 550 to wait for receipt of the block again -:
when the ho~t 200 retransm1ts it in re~ponse to the negative acknowledge message. If tlle reply was "po~itive", on the other Sland, contro1 returns to recelve image routine 532 ~hown ln FIGURE 9.
Refexring once again to EIGURE 9, after return from terminal 'islave" ~elect routine 502, display terminal 300 te3ts whether an "end ~l~v~" 1ag has been ~et (deci3ion block 544). ~ Ret "end 31ave"
flag indicates that the diqplay termln~tl is to exit : .
;, ~.Z885~L6 the "~lave" mode and to ret~lrn to the TTY mode.
Under these circums-tances, display terminal 300 transmits an "abort" ~equence to host 200 anct disables all time-out timers (bloclc 545). If upon returning to routine 532 the display terminal determines that "protocol abort" 1ag is set (decision block 546), it cease~ displaying the graphics screen on monitor 304 (and begins displaying text), and also disables all active timers (block 547). If terminal "slave" routine 542 :-returns without the "end slave" flag or "protocol abort" flags being set, this indicates that an entire block of image data was correctly received from host 200. This received block is "painted" on the graphics display (via graphics card 318) and displayed on monitor 304 (block 548).
Referring once again to FIGURE lO, if no data is correctly being received from host 200 and no reply has been "enabled," display terminal 300 tests whether too much time has passed since it received the beginning of the format block of image data from host 200 (decision block 564). If too much time elapses since the last data block was received, the display terminal 300 assumes it entirely missed receiving the block, sets the "reply and enable"
flag to "remind" itself to tran~mit a negative acknowledge message to the host, ancl sets the "lev~i" state variable to level ~ (block 566).
Display terminal 300 also determines whether it has waited too long to receive the c~lrrent image (decision block 568). Display termina1 ~00 autonomously aborts the image rece.tve operation if it has waited too long for receipt o~ the curr0nt - , , . ~ ,-' ~ . . :. ~:` ' , , .
.
- . . .
.: . . : : , :
,; - , .

~5 63423-267 lmage by ~nding the "protocol ~bort" flag (bloc1c 570) to be tested by FIGURE 9 decis~on block 546.
Finally, if display terminal 300 i~ not currently receiving data or transmitting a reply and no time-outs have occurred, the display terminal te8t8 whether the u~er has req~t~c3ted the entlre image receipt operation to be "aborted" (e.g., by testing the content~ of the keyboard buffer) (decision block 572). If the ~1ser l1a~ req-1e~'ted an "abort", the "user abort" flag .is set (block 574) and reply i~ enablad if the "level" ~tate variable i~ set to level 0 (decision block 576; bloclc 578).
If decision block 550 determines that a new bloc~ of data i9 being received, the "intrablock timer" (the value of which is tested by decision block 564 to determine whe~ too much time has passed during reception of the correct of data) ls reset ~block 580~, and display terminal 300 begins executing "slave" receive ro~tine 582.
_~ "Slave" routine 582 (shown in detail in FIGURES
1~24-128~ is a routlne performed by display terminal ~:
3QO to--receive blocks of imaqe data transmitted by ho~t`200. When di~play terminal 300 first ex~cute~
ro~tine 582, it operates at level 0 ~because the "level" ~tate variable was ~et to the value 0 at FIGURE 9 block 540). Decision block 590 tests the value.of this "level" ~tate vaL.~a1~le. During level ~:
0 operation, the display terminn1 flwnlt~ receipt of a comntand from host 200. ;~
Befora tran~mitting image data, ho~t 200 first transmit.C~ two ~pecial character~: .a "protocol escape" character and a "start text" character.
Display termlnal 200 tests for tllene t:wo characters -.

~ ~385~i before treating any received data as image data.
Since the probability that di~play terminal 300 would mistake line noises for these two successive special characters is extremely small, it is highly unlikely that the display terminal will ever be "fooled" into erroneously treating noise or other characters as image data.
Besides the "protocol escape" and "start text"
special characters, host 200 may also transmit other special characters to display terminal 300. For example, the ho~t may transmit an "in~uiry" special character to the display terminal to request a reply. In addition, the host may instruct the display terminal 300 to cease operating in the "slave" mode and to return to the TTY mode.
During operation in level 0, display terminal 300 simply wait~ for receipt of one of the ~pecial characters transmitted by host 200. If the display terminal receives the "inquiry" special character ~decision block 592), it sets the "reply and enable"
flag to reply to the host's "inquiry". If the display terminal receives the host instruction to cease operating as a "slave" (daciRion block 596), the "end ~lave" flag is set (block 598~ (the value of this flag is tested for by FIGURE 9, decision block 544). If the display term~nal receives the ~pecial "protocol e~cape" character dllring operation in level 0 (tested ~or by decl~lon block 600), it begin3 operating at level 1 to await receipt o the special "start text" character.
Decision block 602 causes display terminal 300 to operate at level 1. During oper~tlon at level 1, the display terminal awaits recelpt of the "start ~ . .
-, .... .
,.~ ,, : ~ ` ,~ ' ':

885~L~

text" character -- which precedes all host image data block transmissions. If an "abort" condition is detected during operation in level 1 (as tested for by decision block 604), the "protocol abort"
flag is set to later cause the ~isplay terminal to return to TTY operation (block 606). If the next character received from host 200 is not the special "start text" character (tested for by decision block 608), display terminal 300 ret~lrns to level 0 to await further commands issued by the host (block 610). I the "start text" char~cter is received, on the other hand, display terminal 300 prepares for receipt of a block of image data by clearing previously calculated checksum information;
initializing a pointer into a block data buffer preserved in RAM 314; setting and enabling the timer used to determine how much time has elapsed since receipt of the initial portion of the current data block; resetting the activity timer; and forcing the display terminal to beqin operating in level 2 .
(blocX 612). ~ :
During operation in level 2, display terminal 300 receives ima~e data characters from host 200 and stores them in its buffer (block 614). In addition, di~play terminal 300 calculates a running checksum o received characters for purpo~e~ of determining whether the block was correctly recRived (block 616~.- Display terminal 300 will continue to operate in level 2 until it receives a speclal "protocol escape" character from the host (a~ tested for by deci~ion block 618), prompting the display terminal to begin operating in level 3 ~block 620).
In ].evel 3 operation, displAy terminal 300 . .: . . - . : : . , -.
, .
, - ~ ;

~! ~8t35~

tests for possible receipt of a special "end of text" character indicating end of transmission of the current block (decision block 628~. Characters received during level 3 operation are checked to determine whether they are "abort" characters (decision block 622) -- suc:h characters prompting the display terminal to set its "protocol abort"
flag (block 624). Characters which are not "abort"
characters are added to the running checksum (block 626) and then tested to determine whether they are - the ~pecial "end of text" character (decision block 628).
Received "end of text" characters ca~l~e display terminal 300 to "disable" intra~lock time-outs and to begin operating in level 4 (block 630). Since level 4 operation is used to receive checksum data which is appended by ho~t 200 to each transmitted :~
image data block, display terminal 300 ceases its block time-out operations to give the host ti~e to . calculate the checksum data (in some host arrangements, it may be desirable to transmit an entire block o data, and only then calculate and tran3mit checksum data, as opposed to first calculating checksum and then transmitting the data block with appended checksum data).
If the character received during level 3 ;:
operation i~ not the "end of text" character, display terminal 300 determine~ whether the character i the "protocol escape" character ~decision block 632). A "protocol escape" character is added to the buffer (permitting imaqe data to contain "protocol e~cape" charactera) -- but only if the host tran~mits two succe~ive "protocol .... ,. . . - , . : . .

: . . .. : ~ .
- .: . . . :
. .. . ~

~ ~88~6 ~9 . 63423-267 escape" characterq for eac}l "protocol escape"
character embedded in the image data ~block 634).
That i3, the fir~t "protocol escape" character cau~e~ the ho~t 200 to enter "]evel 3" operation --and the second "protocol escape" character is stored in the receive data buffer and causes the host to return to "level 2" operation. Display terminal 300 finally returns to level 2 operation whenever it receives any character other than an "abort" or "end of text" character during level 3 operation Iblock~
636, 638~.
Di~play terminal 300 receives a first checksum character during level 4 operation (i.e., after receipt of an "end of text" character). This first checksum character i~ stored (bloclt 640), and the display terminal then operates in level 5 to receive and ~tore the second checksum character (block 64~). In the preferred embodiment, the ho~t 200 transmit~ a 2~byte checks~lm field calculated using convantional CRC algorithms ~altho-l~h other conventlonal error checking algorithms would al90 be suitable). When display terminal has received and stored both byte~ of the ch~ck~um field, it compare~
those byte~ with the running check~um lt has calculated (i.e., in block~ 616 and 626) (block 644). A check~um error cause~ clisplay terminal 300 to transmit a "no acknowledge" ~N~K) reply, whlle a posit~ve check~um result prompts the display ~ -terminal to send a positive acknowledgement message to the host.
Since the di~play terminal 300 i~ ~till operating in the "slave" mode at tlle polnt it receives and analyzed check~um d~ta, It simply : ~ .

:, , , ~ :.- . :: . .

- . : :: ~ ~ . . : , - ~ ' ' . ' .: , ., ~85~

go 63423-267 "enable~" an appropriate reply (either po~itive or negative acknowledge~ (blocks 646, 648). If a po~itive reply i~ to be ~ent, t}le "po~itive reply"
toggle i9 "toggled" 80 tllat tlle next po~itive reply ha9 an alternate value (block 648). That i~, if display terminal 300 acknowledge~ correct recelpt of the last-transmitted image d~ta block with ac]cnowledgement message "ACK0," then the "positive reply" toggle i~ "to~gled" to 1 ~o that corr~ct receipt of the next-transmitted data block will be acknowledged with the positive acknowledgement messaga "ACKl" -- and vice ver3a.
Alternating-valued acknowledgement me~ages are u~ed in the preEerred embodiment bec~use host 200 typically begins transmitting a block of data before it has even received an acknowledgement message relating to the previously transmitted data block.
The transmitting host use-~ the alternating-valued acknowledgement messages to "ma~ch-up"
acknowledgement me~sage~ with transmitted data block~.
Bloc~ 642 re~ets the "level" state variable to level O -- causing the display terminal to expect a special character to ba received next.

~OST COMMUNI~TIQNS RO~rINE
:.
FIGURES 13-21 are detailed ~chem~tic flow charts of steps performed by l-o~t 200 to retrieve, delete and/or ~tore image~ in respon~e to u~er input. FICURES 12A-12C is a flow chart of the overall image management routine "PHOTO-FILE" executed by host 200 in respon~e to user inp~lt commAnd "SPEI,"

,;`.'"

~: , . ............................... . .

,. ~ , . . ... . . .. .

38~

"PH0 or "DPH." This routine first decodes the user input command, and sets a flag to indicate whether the user has requested an image to ~e added, deleted, or retrieved (block 702). Next, the host transmits to display terminal 300 a request for identification (block 70~) and waits to receive a response. A text time-out routine (block 706) inqures that a response is received from displ~y terminal 300 within a reasonable time period.
FIGURE 14 is a flow chart of text time-out routine 706. The text time-out routine is interrupted-driven in the preferred embodiment, but is shown explicitly in the sequential flow chart for purposes of clarity. Text time-out routine 706 sets and enables an input timer (block 708), and then awaits receipt of data from display terminal 300 (decision bloc~ 710~. If the time period being timed by inpu~ timer block 708 expires before data is received (as te~ted for by decision block 710~, the management routine 700 is exited ~block 7103.
If data is received before this timer "times out,"
the input timer is "disabled" (block 714) and the received data is tested to determine whether it is a display terminal "escape" sequence Iblock 716). The display terminal user indicates he wishes to discontinue image processing by entering this d1splay terminal sequence -- and time-out routine 706 accordingly exits management ro-ltine 700 in response to this "escape" sequence. If the received data is not the "escape" sequence, time-out routine 706 returns to the routine which called it (in this case, to execute decision block 718 ~hown ln FIGURE
12).

`

-.' : ' ~ . ' ~ : '' , .
.
. ~ ` , ' .: ' '. ' :` ' 885~

Decision block 718 shown in FIGURE 12 determines whether the received display terminal identification requested by block 704 is valid for the requested function. For example, some dlsplay terminal3 300 may be authorized to "retrieve"
imageR, but not to store or delete images. Other display terminals may have authority to "delete or retrieve" images, but have no "capture"
capabllities. Still other diqplay terminal~ 300 may not have any graphics capabilities, and therefore are completely denied access to image management routine 700. If decision block 7l8 determines a reguesting display terminal does not have authority or capability to perform the image function it has requested, the routine transmits an error message and exits back to the "SIGNON" task (block 720).
If the received data terminal identification is valid for the requested image function, a message confirming the requested function is transmitted to the di~play terminal (block 722) followed by a prompt for real estate property listing number (block 724). Time-out routine 706 is then executed again, and when a response to the listing number prompt has been received from the display terminal, it is checked for valid format (block 726) and an error message is sent if the received format i9 invalid ~block 728). Host 200 then cross-checks the listing number in the MLS 11~tlng database to -determine whether a listing for the inputted listing number exi~ts (decision block 730). If no listing number exist3, an error message to that effect is transmitted to display terminal 300 (block 732) and the user i.s "prompted" for a new 11stlng number . ~

-. ~ , . . . .
.

~1.2885~i (block 724).
Assuming that the listing number inputted by the user is valid and corresponds to a property that is listed for sale, host 2C)0 branches to different sections of management routine 700 depending upon the function the user has re~ested. Decision block 734 first determines whether the user has requested an "add" (store) of a new photo to the image database. If the user has not requested a photo to be added, test and delete routine 736 is executed to determine whether the user has requested a photo to be "deleted" and to delete a photo in response to such request. A flow chart of the test and delete routine 736 is shown in FIGURE 13.
Referring now to FIGURE 13, decision block 73a -tests whPther the user has requested the "delete"
function (if delete has not been requested, control returns to decision block 740 e:hown in FIGURE l~
sinca the user has requested a "retrieve"). If a "delete" has been requested, host 200 sends to display terminal 300 the geographical address of the property corresponding to the inputted listing number (block 742) along with the numbers de~ignating photos in the database corre~ponding to that listing. In the preferred embodiment, up to sixteen photos can be stored or any one property listing. In addition, the preferred embodiment ~
designates photos at the time they are stored in - -accordance with user preferences. For example, a user may decide to designate three images he store~
in connection with a particular property listing as photo number I, photo number 3 and photo number 4.
In the preferred embodiment, there i9 no requirement ,. : - . , . : . : .

: .
,~ , .
' ' ~' ,: . . ', ' :. : ' ~1 28~35~;

to store photo number 2 before storing photo number 3. Images are retrieved in the order of their numerical designations, not in the order they were ~tored. This feature of th~e preferred embodimen-t adds flexibility as will be appreciated.
Routine 736 then sends a "prompt" requesting the user to input the photo number he wishe~ to "delete" (block 746), and executes "time-out"
routine 706 while waiting to receive the user response. If the user response h~s an invalid format las testad for by decision block 748), host 200 transmits an error message to the display terminal (block 750) and retransmits the photo number "prompt" (block 746~. If the format is valid, it is determined whether the photo requested to be deleted exists (decision block 752). If the photo exists, it i9 deleted (block 754) by reguesting photo file manager module 731 to delete the corresponding image file. If the photo requested by the user to be deleted doe~ not exist, then it i3 determined whether the u~er inputted the number 0 (indicatlng that he made a mistake and he does not wish to delete a photo after all~ (decision block 756~. If the number 0 was inputted, control returns to block 724 in FIGURE 12 to "prompt" for a new listing number. If the u~er did not input a zero, an error message is tranamitted to the display terminal (block 758) and the u~er i8 "prompted" for a new photo number (block 746).
If decision block 734 determines the user ha~
not requested a new image to be "~tored" and deci~ion block 738 determine~ the ll~er has al~o not requested "deletion" of an image f~le, then the user . ~
. : - , . : . , ,~ .. . .

~ass~6 must have requested "retrieval" of an lmage -- and decision block 740 shown in FIGURE 12 determin~s whether any images have been stored in connection with the u~er-lnputted listing number. If no such images have been stored, host 200 transmits an error mes~age to that effect to dis~lay terminal 300 (blocX 760). On the other hand, if there are images stored in connection with the inputted listing number, host 200 transmits the numbers of the stored photos, and then performs the step~ required to transmit the "mini-li3t" (i.e., ~ends a special character se~uence indicating the start of the "mini-list", sends the actual text of the "mini-list", and then sends another special character sequence requiring the receiving display ~`
terminal 300 to return to the TTY asynchronous terminal mode (~Iock 762)). Routine 764 i~ then executed to "retrieve" an image from a file stored on disk 206 and to transmit digital data signals representing the image to display terminal 300 for display. A detailed flow chart of the ho~t retrieve image routine 764 is shown in FIGURE 15.
Referring now to FIGURE 15, ho~t 200 "retrieves" a photo from its image file database by providing file manager module 231 with the index key a~sociated with the file ~i.e., listing number and photo number~ and then waiting for the file manager to return a send block containing the contents of the image file. If this retrieve operation i9 not successful (tested for by decision block 782), host 200 sends an error message to that effect to display terminal 300 (block 78~). If the retrleve operation was a success, on the other hand, ho~t 200 transmits . . ~ , . , .: - : . . . . : - . :

38~i~6 start photo sequence characterts~ to di~play terminal 300, ~et3 an activity timer and a retry counter, and begin~ operating as a "master" in the blocked image data trangmission protocol dlscussed previously in connection with the operation of the dlsplay terminal (block 786). ~s will be explained, the retry counter i~ u~ed by host 200 to control the number of times it will retry transmi~sion of a block of digital data before giving up.
Hoat 200 then transmits an "inq-liry" to display termlnal 300 (block 788), exits back to ho~t image management routine 700 lf it ha~ already retried transmission of the current digital dAta block a predetermined number of times (e.g., five in the preferred embodiment), (deci~ion block 790) and executes a response time-out routine 792 while waiting for a respon~e from display terminal 300.
FIGURE 17 is a flow chart of respon~e time-out routine 792. Thi~ time-out routine ~imply waits a maximum predeterm~ned t~me pariod to receive a respon~e from a di~play terminal (block~ 794, 796, 798), accepts the received value as the reply (block 800) a~d ~ets the reply to an invalid state i no data i8 raceived from display terminal 300 within a predetermined time period (block 802).
Referring once again to FIGIJRE 15, if the reply received from the di~play termlnnl w~s not positive (decision block ~04), th~ retry counter i9 decremented (block ~06) and control is returned to block 788 to aend the "inquiry" once ngnin ~o long as the reply 18 not invalid (i.e., no long as the dlsplay termlnal returned some reply whlch wah recelved by the host) (block 808~ block 802 .. . . . : , . ~ .. ~ :

. . . ~ , ~ . . , ~ . : ..

. : . : . :. . . ' . .
: ~

38S~6 shown in FIGURE 17 sets the reply to an invalld value upon not receiving any response at all from the display terminal within the time-out period, on the other hand, routine 764 is exited and control returns to routine 700.
If a positive reply was r'ec'eived (decision block 804), it i8 determined whether any more image data for the current image remains to be transmitted (decision block 810). If more image data remains, a block of data is moved from the dynamic memory area received from file manager 231 to a temporary transmit buffer (out of which data is transmitted to display terminal 300) (block 812), and that block is then transmitted out of the b~lffer -to the display terminal (block 814). Transmit image routine 814 iQ
shown in detail in FIGURE 16.
Referring now to FIGU~E 16, to tran~mit a block of image data to display terminal 300, the retry counter is first initiali~ed to five (to permit the host to retry tran3mitting the ~ame blocX of data a ~
maximum of five times~ (block 820j. The retry .
counter is then tested to determined whether it ha~ :
been decremented to 0 (decision block 822), and if tGo many retrys have occurred, a "protocol abort"
character i~ transmitted to the disp1.ay terminal 300 to cause the display terminal to e~it the blocked data receive mode and return to t.he TTY mode (block 8~4). If too many retrys have not yet occurred, a running checksum counter and a buffer point are initialized (block 826), and data i~ then transmitt.ed one character at a time from the buffer to the display terminal until all ch~racters of the block have been transmitted (deci~ion block 828;

Y~. - - . . .

..

block 830). In the preferred embodiment, a running check~um is calculated as characters are transmitted (block 830). When the entire block (up to 2048 byte~ in the preferred embodiment) have been transmit-ted, host 200 transmits a "protocol escape"
character and an "end of text'' charac-ter to indicate to the display terminal that block transmission is complete (block 832).
The running checksum value is then tested to determine whether it is a "legal" value (decision block 834~, and modified to make it a "legal" value if necessary (block 836). It ha~ be0n ound that equipment commonly found on conventional dial-up lines (e.g., error correcting modems, data multiplexers, and the like) may improperly respond to certain special characters which would normally be transmitted as part of the ANSI X 3.28 protocol.
In particular, much of this equipment looks at the low-order six bits of each and every byte which is transmitted, and if it recognizes any such character as would fall within the range of hex 00 to hex lF, such equipment commonly rPspond to the byte ai~ i it were a special "protocol" character. Depending -~
upon the equipment involved, unexpected or undesirable results may be obtained. For example, some e~uipment 5imply treats 9~1Ch characters falling within this range as control cllflrRcter intended for it and does not even pas~ the char~cters on. Other equipment may repeat the character (i.e., insert an extra, duplicate character immediately following retransmis~ion of the first3.
For example, it has been found that the ~tandard "data escape" character called for by the ~ . . .
:. : - '' ' . .' ' -' : ..
.

-- ~ ~ . . ..

385~6 standard ANSI X 3.28 protocol is repeated in this manner by data multiplexers commonly found on dial-up lines. If host 200 were to transmit a single "data escape" character, the first multiplexer on the line might repeat the character (to place two "data escape" characters in the serial bit stream at the point where the host transmitted only one), and other multiplexer-~ down the line typically would do the same. The result was found to be that single "data escape" characters transmitted by host 200 would cause display terminal 300 to received many such (even hundreds of) "data escape" characters.
To make the blocked data protocol of the preferred embodiment compatible with standard dial-up line equipment, host 200 never transmits a byte haYing a hex value within the range of 00 to lF
in its lowest order six bits. Sometimes, however, checksum values may fall within this range. To avoid confusing dial-up line multiplexer and other e~uipment, any checksum value which does fall within this "illegal" h -lFh range is modified by ORing it with octal value 100 (e.g., adding a logic level 1 in the 64th bit place) to prevent the value from falling within this "illegal" range.
After modiying the check3um as neçessary, host 200 transmits both bytes of the running checksum (block 838) and exectltes response time-out routine 792 to wait for an acknowledge from display terminal 300. If display terminal 300 transmits a negative acknowledge message in re~ponse to receipt o the just-transmitted block (as te~t~d by decision 840), the block is retranRm1tted by routine .. . ~ , .

~88S~6 814 (after determining that the block has not already been retransmitted five or more times and that a valid but negative reply was in fact received from the display terminal) (blocks 842, 84~, ~22).
If display terminal 300 positively aclcnowledges receipt of the just-transmitted block, control returns to routine 764, decision block 810 (FIGURE
15) to determine whether additional image data remains to be transmitted. If more image data remains, the next block of data is moved into the transmit buffer (block 812) and ro~tine 814 i~
executed to transmit that block of data.
When no more image data remains, hcst 200 sends a special character to display terminal 300 making the display terminal the "master" and then itself becomes the "slave" (block ~S0). In the preferred embodiment, host 200 acts as the "ma3ter" and thus controls the operation of tha display terminal "slave" during the entire time image data is being transmitted from the host to the display terminal.
As "master," host 200 transmits blocks of data and is not interrupted by display terminal tran~missions, since the di~play terminal (a~
"slave" ) can only transmit during times when the host is not transmitting -- and even then is capable of transmitting only a very limlted repertoire o responses to host transmission~, ~e.g., "NAX,"
"AK0," "AKl" or "abort"). After an ent~re block has been transmitted, however, host 200 in the preferred embodiment sends a special "escape"
sequence which cauRes display termlnal 300 to operate as the "master" and then ltself becomes " lave." The reason for this 1~ to glve display ': . .' ' . : ~ ' . ' , . , 35~6 terminal 300 the opportunity to positively recognize that host 200 considers itself to have transmitted an entire, complete and "good" image to the display terminal without requiring the use of any other special characters to signify end of image transmission. ~ ~
After becoming "slave," host 200 simply waits to receive data from display terminal 300 -- without executing any of the time-out routines since the host is now acting as a "slave" but conditioning receip-t of a command from the terminal on falling within the activity time-out period (decision blocks 860, 862). If no response has been received within the activity time-out period, a "protocol abort"
character is transmitted to the display terminal and routine 764 is exited (block 864). I~ data is received from the display terminal, it is tested to determine whether it is an "inquiry" (the data the host expects to receive from the display terminal upon correct receipt of an image) (decision block 866). If an "inquiry" is received, host 200 transmits a positive acknowledgement message, resets an activity timer, remains the "slave" and awaits : further data to be transmitted by the display terminal (block 868; decision block 860). If the recaived data is not an "inquiry," then host 200 deter~ines whether the received datA indicates the display terminal has given up control to make the host the "master" once again (block 870~. If the di3play terminal has given up control, host 200 transmits the "protocol abort" char~cter (block 864) and exit~3 to routine 700. If the recslved data is neither an "inquiry" nor the "give-up control"

.

~ 2~ 516 escape sec~ence, then host 200 determines whether the received character is an "abort" (decision block 872). The terminal "abort" character cause5 host 200 to transmit a responsive "protocol abort"
character (block 864).
Referring now once again to FIGURE 12, after host 200 "retrieves" and transmits an entire image (block 764), it transmits the " asynchronous escape"
sequence which causes display terminal 300 to return to the asynchronous TTY mode (block gO0), and then determines whether the image it just transmitted was for the first photo tdecision block 902). In the preferred embodiment, display of the first (but not later) photos on the display te~minal graphics screen is followed by display of the full text MLS
listing on the display terminal conversational screen. Accordingly, after transmi ~sion of the first image, hoc~t 200 transmits the full text listing (block 904). Host 200 then determines whether additional photos corresponding to the llsting exists 5decision block 906). If additional photo~ do exist, the host "prompts" the user for the number of an additional photo (block 908), eKecutes time-out routine 706 while waiting for a response, :.
and then after determining the response is in valid format, tes~s the response to determine if the user ha~ requested display of an a~ld~tion~l image ~deci~ion blocks 910, 912). If the user has regue~ted display of an additional image, retrieve image routine 764 is executed once again. If the uYer does not request display of another lmage, the host transmits the listing number prompt (block 724).
In the preferred embodiment, A u~er may "add"

: . ,. ~ ~ - : .
~, . . ~ , . ,, ,- , . . .~- ' ' . , ' .
. ~. ' . ,, - . ' ~L2~85~;

images to the image file database on an interactive baRis. I the user requests storage of an image (as tested for by FIGURE 12 decision block 734), host 200 transmits the geograph:Lcal address of the property corresponding to the inputted listing number for verification by thé- user along with the numbers o currently stored photos (block 914~. The property address is transmitted to permit the user to verify the address corresponding to the property (since nine d.igit listing numbers are often confused, but street addresses are more difficult to confuse and are more easily understandable by users). Host 200 then transmits a "prompt" for the photo number to be "added" (in the preferrad ~-embodiment, the user may "add" photos to the database in any de~ired order), and then waits for and validates the response (blocks 916, 918). A
zero response allows the user to "abort" the .
operation and causes host 200 to transmit the :~
listing number prompt again (blocks 926, 928, 724).
If the user ha~ responded with an available photo number, however, host 200 executes the "ma~ter/~lave" select routine ~block 930) to capture the transmitted imaqe. -~
A detailed flow chart of t.he "master/slave"
~elect routine 930 is shown in FIGURE 18. In the preferred embodiment, ho~t 200 b~comes "~lave"
during receipt of image data betng transmitted by display terminal 300. "Ma~ter/slave" select routine 930 causes host 200 to begin operating in the "slava" mode. Host 200 first transmlts a requests for photo sequence, sets and enables the actlvity timer, initializes the retry counter, enter~ the .. . , ~ . . . .

~2~385~6 10~

"master" mode and then transmits an "inquiry" to display terminal 300 ~block~, 932, 934). "Inquiries"
are repeatedly transmitted until a positive response is received or until the retry counter has been decremented to zero at which time the host "gives-up" and returns to image~management routine 700 (blocks 936-946). If the host finally receives a positive, valid reply to its "inquiry" (a~ te4ted for by decision block 940), it transmits a pecial "escape" sequence to the display terminal 300 indicating to the display terminal that the host i~
entering the "slave" mode and that the display terminal is to begin operating as "master" (block 948). Host 200 then begins executing "slave"
routine 950 -- during which operation it receives image data transmitted by the display terminal.
A detailed flow chart of "e,lave" routine 9S0 is ~-shown in FIGURE 19. After initializing a receive buffer and associated buffer pointer, activity timer, positive reply "toggle" and "level" state variable (block 952~, host 200 executes a "~lave"
time-out ro~tine 954 to insure that it does not remain a "31ave" for a long period of time during which the display terminal fails to transmit data.

A flow chart of the "slave" time-out routine 754 is, shown in FIGURE 20. If dAta i9 not received from the display terminal (as, tested for by decision blocX 956), host 200 determines whether it ha~, "enabl,3d" a reply (block g58) (just a8 discussed in connection with display terminal, when acting as "slave" the host can only transmlt chsracters to the "master" display terminal durlng times when the ,. -, : . - - :.
:, - ~

.; - : .: :. . ,:
.. ~
~: ~ - ' . . . .... .
: ... , : .

35~

display terminal is not acl:ually -trans~itting data~. If a reply is "enabled," the host tran~mits the reply (block 960~ and, if the reply is not positively acknowledged (as te~ted for by deci~ion block 962), retransmit~ the reply until either the reply i9 positively acknowledge or until the activity time-out period has expired (ac~ tested for by decision block 964). If the activity time-out period expire~ (indicating that host 200 has not received any data from the display terminal for more than a predetermined ac-tivity time-o~tt period), the "protocol abort" flag is set to cause the host to tranC3mit an "abort" character to the display terminal at the next available opportunity (block -966). Host 200 also keeps track of how long it has waited to receive the current data block and if a corresponding time-out period expires, it "gives up" ~ -receiving the block and transmits a negative acknowledge message to the display terminal to force the di~play terminal to retransmit the block (decic~ion block 968; block 970).
When data i9 finally received from display terminal 300, host 200 resets the "intrablock" timer (block 972) and then ~xecutes the host "slave"
routine (block 974) to actually receive the image data.
FIGURES 21A-21B are together a detailed flow chart-the ho~t "c~lave" routine 974. This routine i8 virtually identical to terminal "slave" receive 582 shown in (and di~cu~ed in detail in connection with) FI~URE 11. In the preferred embodiment, ho~t 200 stores received image data as lt receiv~ it :.
without ~dditional processing. Hence, "modified" ~.

.. : .: .
" . : ' ' , , -,.' ' ' ,::': . ' : ~' - ' ; ': . ', ': , . .
~. , 35~;

character~ and embedded "p:rotocol escape" character~
are stored with the image data as received.
However, host 200 does accommodate "modified"
checksum characters by modifying calculated checksum values falling within the "illegal" ranga before performing conventional error-checking comparison.
Upon receiving "positive" reply from host 200 in response to its own tran~mitted reply (blocks 960, 962 of "slave" time-out routine 954 shown in FIGURE 20), host 200 returns to execution of "slave"
routine 950 shown in FIGURE 19 and ~etermines whether it is to continue to act a~ a "slave"
(during operation and "level O" shown in FIGURE
21). Host 200 "looks for" receipt of an "escape"
~eguence from display terminal 300 indicating that the display terminal has cea~ed operating as "master" and now allows the host to operate a~
"master." When display terminal 300 gives up control (as tested for by FIGURE 19 decision block 976), host 200 reverts to operating as "master"
(block 978) and then returns to "master/slave" ~ -select routine shown in FIGURE 18. Otherwise, host 200 continues operating as "slave" until either a time-out occurs or until a "protocol abort" occurs "
(e.g., in response to an "abort" charact~r tran~mitted by display terminal. 300~ (blocks 980, 982, g84).
Referring now once again to F~GURE 18, upon return from "slave" routine 950, the buffer pointer i5 tested to determine whether it ha~ been incremented (decision bloc~ 986). If the buffer pointer ha~ not been incremented, then no image data has yet been received and blocks 948 ~nd 950 are - - . , . - , . :
- - . ' :

.
-. ' : - ~ . ' .
.,: - . . , . :

35~

executed once again. If an image ha~ been received, however, the contents of the receive imaqe buffer i~
read into an image file (block 988) through file management module 931. Host 200 then transmits a success or error message depending upon the completion codes it receives from file management routine 231 ~deciRion block 990, blocks 992, 994).
Control then returns to image management routine 7U0, block 724 (shown in FIGURE 12) to "prompt" for a new listing number.

DISPLAY TE~MINAL IMAGE_ChPTURE_OPERATION

FIGURES 22-26 are detailed flow charts of the capture image rcutine 1000 performed by display terminal 300 to capture and tran3mit images to host 200. Capture image routine 1000 i~ called from the ~asic conventional monitor program executed by display terminal 300 upon input by the user of the command "SPH" (FIGURE 22 block 1002).
Display terminal 300 awaits for receipt of data from host 200 (block 1004) and then tests whether the received data i9 "protocol" se~uence data or simply "text" data (block 1006). Generally, display terminal 300 operates in the TTY mode by simply displaying on its conversational ~creen all "legal"
characters transmitted to it by ho~t 200 (block 1008, 1010). If a special "protocol" sequence :~
character is received, however, display terminal 300 analyzas the character to determine whether it is an identification "inquiry" -- and if it i8, immediately responds with a predetermlned terminal identification assigned to it (blocks 1012, 1014).

.. . . - . . : . . ..

, . .: ~ , ' ' ,': ' .' ~ ', ~ .

.
~ ~ - ., ~ ' ... . .

~ ~8851~

If the recei~ed special "protocol" sequence character authorizes display terminal 300 to transmit an image to host 200 (tested for by decision block 1016), the cli~play terminal begins operating in the "slave" mode and control~ graphics card 318 -to digitize and "acq~ire" an image produced by VCR (or other video source) 306 (blocks 1018, 1020). If a predetermined time-out period expires :
before a complete image is acquired, a "master/slave" æelect routine 1024 ~to ~e described shortly in connection with FIGURE 24) i~ executed to ~:
return to the TTY mode. When an image is acquired, a transmit image routine 1026 is executed to actually transmit the acquired image.
A detailed flow chart of the tran~mit image routine 1026 is shown in FIGVRE 23. The display termlnal display screen 304 i~ returned to the interactive moda (so that it displays communications received from ho~t 200 rather than the digitized acquired image) ~block 1030), and then display terminal 300 determines whether the user requested imaga acquisitiQn to be aborted by keying in an "abort" command during image acqui~ition ~deci3ion block 1032). If image aGquisition was aborted, di~play terminal 300 transmits a "protocol abort"
me~age to indicate to host 200 that an imase is not to be transmitted and that the di 8pl~y terminal 300 i9 to return to the TTY mode (block 1034).
Display terminal 300 then determines whether it i~ still operating as a "slave" (block 1036).
Display terminal 300 doe~ not transmit any image data until it has b~come "master" And host 200 is operating a~ "slave." However, the di~play terminal ': , - :- : ' ' .
- ~

" ~ ' ' ; " ~ ` ' ' ' :

.

12~3~35~;

cannot become "master" until the host has released control and has itself become "slave." Display terminal 300 transmits an "inq~liry" to host 200 (block 1040~ requesting permission to becoma "master." If display terminal 300 wait~ more than a predetermine time-out period before becoming "master" (as tested for by decision block 1042~, it executes "master/slave" select routine 1024 shown in more detail in FIGURE 24.
Referring now more particularly to FIGURE 24, if the terminal "master/slave" select routine is entered because of a "slave" time-out (e.~., from deci~ion block 1036, 1042) (decision block 1050), di3play terminal 300 detexmines whether it ha~
received data from host 200 (decision block 1052).
If data has been received, display terminal 300 determines whether the recelved data i~ an "abort"
seg~tence -- and if it is, exits to capture image routine 1000 to await additional received data in the TTY mode (decision block 1054, block 105~). On the other hand, if the received data i~ a contmand to display terminal 300 to become "master," the display terminal begin~ operating a~ "master" (daci~ion block 1058, block 1060). If the received data i~ an 'tinquiry," on the other hand, display terminal 300 transmits a positive acknowled~e me~sage (deci~ion block 1062, 1064).
When decision block 1036 flhown in FIGURE 23 finally determines that host 200 has granted display ~erminal 300 permission to act as "master," it tran~mit~ an "inquiry" to the host ~bloclc 1040) and then waits for a response from the hoat (d~clsion block 1042, 1044). Time-out rotttlne 1044 shown in .: : . : .. ~ . .: .

~ ~885:a 6 detail in FIGURE 26 prevents display terminal 300 from waiting more than a predetermined time-out period for a response to its "inquiry." If the reply to "inquiry" i9 positive (deci3ion block 1046), display terminal 300 de-termines whether there is additional image data not ye~ transmitted (deci~ion block 1048). If additional data exi~ts, display termlnal 300 determines whether the next data byte is a "legal" character (i.e., whether it fall~ outside of the range of hex 00 to hex lF) (decision block 1100). If the next character is not a "legal" character, it is ORed with octal value 100 in the preferred embodiment (thtls modifying it to make ~t have a i'legal" value) and then i5 added to the buffer (bloc~ 1102, 1104). If the character is "legal" it i5 ~imply added to the buffer (blocX
1104). This process is repeated until the data block buffer is full (a~ te~ted for by decision block 1106). When the data buffer becomes full, send image data routina 1108 is executed to transmit the buffer content~ to host 200.
A detailed flow chart of the send image data routine 1108 i~ ~hown in FIGURE 25. A retry counter i8 se~ (block 1110), and then the retry counter is tested to determine whether it has expired (decision block 11123. Data terminal 300 only attempts to transmit the same block a predetermined number of retry time~ after which it "give~-up" and transmits a "protocol abort" ch~ra~tar to ho~t ~00 (decision block 1112, block 11143. If less than the maximum permi.tted nu~ber of retrys h~ve occurred, display t:erminal 300 initializes a runnlng checksum value, initializes a buffer pointar used to read '. , ' : - . ~ : :

~.2~85~;

characters from the transmit data buffer, and then transmits a "start of text" character to host 200 (block 1116) to indica-te to the host that a block of image data is to follow.
Dlsplay terminal 300 then transmits image data, character by character, out of the transmit buffer until no more data exists in the bllffer ~decision block 1118, block 1120). When the entire buffer contents have been transmitted, display terminal 300 transmits a "protocol escape" and "end of text"
character to indicate to host 200 that the block is complete (block 1122~, and then transmits its running checksum value at the end of the block tafter modifying same if necessary to make the value fall within the "legal" limits) (decision block 1124, blocks 1126, 1128). Dlsplay terminal 300 then waits for an acknowled~ement from ho~t 200 (time-out routine 1044). If the acknowledgement i~ negative (indicating that the host did not correctly receive the data block), the retry counter is dacremented (decision block 1130, block 1132), and steps : 1112-1128 are executed again. If an invalid respon3e i3 recelved from tha host (a~ tested for by decision block 1134), display terminal 300 transmits .~
a "protocol abort" escape sequence to cause both ~.
di play terminal 300 and host 200 to exit the ~ .
blocked data communication protocol. If a poRitive acknowledgement is received from host 200 (as tested for by dec~sion block 1130~, control i~ returned to tran~mit image routine 1026, block 1098 ~hown in FIGURE 23 to test whether any additional blocks of data should be transmltted as part o the current image.

-: . . ~ . . . ., : . -.

. . :~ . : .... . . .

. ~ . . -~ : .. . : . , ~8~

Referring now once again to FIGURE 23, when no more image data remains to be transmitted, display terminal 300 determine3 whether any additional untransmitted data remains in the transmit buffer (decision block 1200). If such untransmitted data does remain, send image data ~o~ltin& 1109 is executed to transmit the untransmitted data. If no more data remains to be transmitted, display termlnal 300 transmits the "escape" ~equence used in the preferred embodiment to indicate to the host 200 that it no lon~er is operatin~,~ as "master" (block -120~), and control reverts to capture image routine.
lOOO.shown in FIGURE 22.

DETAILED DISCUSSION OF OPERATION OF
SYSTEM 100 F OM STANDPOINT OF A.TYPICAL

The lengthy appendix attached hereto describe how system 100 is used by a typical realtor to manipulate text and image data, retrieve and display image~, add new images, delete images, print images, locally store and later manipulate retrieved images, and execute setup routines to initialize display terminal 300.

While the invention has be~n de~cribed in : connection with what is pre~ently considered to be the most practical and preferred embodiment, it is to be understood that the invention i~ not to be limited to the disclosed embodiment, but on the contrary, is intended to cover varlo~i~ modification~
.. ~ .
and equivalent arrangements inclllded wlthin the 35~

spirit and scope of the appended claim~.

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Claims (19)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A system for displaying information corresponding to real estate properties comprising:
a host computer system for storing data representing text corresponding to properties and for also storing data repre-senting images corresponding to said properties; and at least one remote data terminal connected to receive video signals representing an image and also connected to said host computer system via a telephone line, said remote data ter-minal including:
means for converting said video signals to digital signals representing said image, means for data compressing said digital signals, means for performing error checking functions on said compressed digital signals and for embedding data represent-ing the results of said error checking functions into said digital signals, and means for transmitting said compressed digital signals and embedded data to said host computer system, wherein said host computer system includes:
means for receiving said signals transmitted by said remote data terminal, means for performing additional error checking functions on said received signals in response to said embedded data, and means for storing said received image representing digital signals and for permitting later retrieval of said image signals over said telephone line by said remote date terminal.

2. A system as in claim 1 wherein said storing means stores said image signals in a file indexed by a key field consisting of a listing number, a photo number, and a segment number.

3. A system as in claim 1 wherein said storing means stores image data in segments, each segment including up to 2048 bytes of image data.

4. A method of transmitting image data between a host computer system and a remote display terminal comprising:
(1) transmitting an escape sequence from the host system to the display terminal directing the display terminal to enter a blocked data transmission protocol, said escape sequence selected from "ESC_SPH" and "ESC_PHO";
(2) transmitting a data packet from the host system to the display terminal;
(3) transmitting an acknowledge message from the display terminal to the host system in response to receipt of the data packet transmitted by step (2);
(4) repeating steps (2) and (3) until all data representing an image has been transmitted; and (5) transmitting an escape sequence "ESC_ASY" from the host system to the display terminal after all said data has been transmitted.

5. A system as in claim 1 wherein:
said host computer system further includes transmitting means connected to said telephone line for permitting later retrieval of said received image signals by said remote data terminal, said host computer system transmitting means including:
(a) means for transmitting an escape sequence from said host computer system to said remote data terminal directing the remote data terminal to enter a blocked data transmission proto-col, said escape sequence selected from "ESC_SPH" and "ESC_PHO", and (b) means for transmitting data packets from the host system to the remote data terminal;
said remote data terminal transmitting means includes means for transmitting an acknowledge message from said remote data terminal to said host computer system in response to receipt of each of said transmitted data packets; and said host computer system transmitting means further includes means for transmitting an escape sequence "ESC_ASY" from the host system to the remote data terminal after all said image signals have been transmitted.

6. A real estate listing information storage and retrieval system with image handling capabilities, said system including:
a host processor including:
mass storage means for storing digital information representing plural real estate listings corresponding to real estate properties offered for sale, and host processor telecommunicating means for tele-communicating said stored digital information over a tele-communications network; and plural user stations remote from said host processor, each remote plural user station including remote station tele-communicating means for exchanging digital signals with said host processor telecommunicating means over said telecommunications network and display means for displaying real estate listing information represented by said exchanged digital signals;
at least one of said remote user stations further com-prising:
generating means, responsive to image signals pro-vided locally to said one user station, said image signals repre-senting an image of real estate, said generating means for genera-ting at least one digital signal message representing said image, and remote station image telecommunicating means co-operating with said host processor telecommunicating means for transmitting said digital signal message from said one remote user station to said host processor over said telecommunications net-work;
said host processor further including file manager means connected to said host processor telecommunicating means for receiving said transmitted digital signal message, for storing said received digital signal message, and for associating said stored received digital signal message with one of said listings.

7. A system as in claim 6 wherein said file management means includes:
means for indexing said stored listing information based on multiple listing number, and means for retrieving stored digital signal messages based on multiple listing number and for communicating said retrieved messages to remote user stations over said tele-communication network.

8. A system as in claim 6 wherein said file manager means includes means for storing said received digital signal message on said mass storage means in a discrete file separate from said stored information representing said associated listing.

9. A system as in claim 6 wherein:

said at least one remote station further includes video source means for providing video signals representing said image;
and said generating means includes graphics means connected to receive said video signals for converting said video signals to said digital signal message.

10. A system as in claim 6 wherein said remote station tele-communicating means includes:
control means for alternately operating in:
(a) a master mode upon receipt of a first control sig-nal sequence from said host processor telecommunicating means, and (b) a slave transfer mode upon receipt of a second control signal sequence from said host processor telecommunicating means; and means connected to said control means for transmitting digital signal messages to said host processor telecommunicating means in said master mode and for receiving digital signal messages from said host processor telecommunicating means in said slave mode.

11. A method of displaying images of real estate property offered for sale at a remote user station connected by a tele-communications network to a host processor, said method comprising the steps of:
(a) transmitting a request for photo function from said remote user station to said host processor;

(b) in response to receipt of said request by said host processor, prompting the remote user station for a multiple list-ing number;
(c) transmitting a multiple listing number from said remote user station to said host processor in response to said prompt;
(d) transmitting a mini listing text format corresponding to said multiple listing number from said host processor to said remote user station;
(e) displaying said mini listing text format at said remote user station;
(f) operating both said remote user station and said host processor in a blocked file transfer mode after said displaying step (e) in response to signals generated at said host processor and transmitted to said remote user station;
(g) in said blocked file transfer mode, transmitting data representing an image from said host processor to said remote user station and receiving said image data with said remote user station;
(h) reconstructing and displaying an image at said remote user station in response to said received image data with said mini listing text format on a first screen;
(i) transmitting a full text listing format from said host processor to said remote user station;
(j) receiving said full text listing format with said remote user station and displaying said full text listing format at said remote user station on a second screen different from said first screen; and (k) allowing said user to alternately view said first and second screens without repeating said transmitting step (g).

12. A system for communicating image and text data repre-senting real estate properties between a host and a remote user workstation over a telecommunications network including in-line components producing responses to certain data signals, said system including:
means said remote user workstation for providing data signals representing an image of a real estate property;
data transmitting means remote user workstation for transmitting said image data signals over said telecommunications network;
data receiving means at said host for receiving said transmitted image data signals;
first translating means connected between said providing means and said data transmitting means for translating only certain image data signals from initial values to other values prior to transmission, said other values inhibiting responses by said in-line components; and second translating means connected to said data receiv-ing means for translating received data image signals having said other values back to said initial values.

13. A system as in claim 12 wherein:

said first translating means comprises means for ORing any initial value within the range of 00hex to 1FheX
with octal value 100.

14. A system as in claim 12 wherein said first translating means includes means for restricting the appearance of octal values within the set of 23, 21 and 05.

15. A system for communicating image and text data associated with real estate between a host and a remote user workstation over a telecommunications network including in-line components responding to certain data signals, said system including:
means at said remote user workstation for providing data signals representing an image of a real estate property and for preparing said data signals for later display by the same or different remote user workstation;
data transmitting means connected to said providing means and to said telecommunications network for transmitting said image data signals over said telecommunications network to said host;
data receiving means at said host connected to said telecommunications network for receiving said transmitted image data signals;
data storing means connected to said data receiving means for storing said transmitted image data signals substan-tially in the form they are received by said data receiving means;

data access means connected to said data storing means for retrieving stored image data signals in response to requests initiated by said remote user workstation; and data transmitting means connected to said data access means and to said telecommunications network for transmitting over said telecommunications network said retrieved image data signals to said remote user workstation substantially in the form they were previously received by said data transmitting means.

16. A system as in claim 1 wherein:
said remote data terminal further includes a volatile image data buffer memory;
said converting means stores said digital signals representing said image in said volatile memory; and said data compressing means includes means for reading said digital signals from said volatile memory.

17. A system as in claim 6 wherein said telecommunicating means telecommunicates said digital signal message substantially immediately upon generation of said digital signal message from said image signals.

18. A system as in claim 12 wherein:
said data signals providing means comprises means responsive for inputted video signals representing said image for digitizing said video signals and providing resulting digital data signals to said data transmitting means; and said data transmitting means transmits said digital data signals without said data signals substantially immediately after said signals have been digitized.

19. A system as in claim 15 wherein:
said data signals providing means comprises means responsive for inputted video signals representing said image for digitizing said video signals and providing resulting digital data signals to said data transmitting means; and said data transmitting means transmits said digital data signals without said data signals substantially immediately upon digitizing of said data signals.