A portable servowriter system for writing a closed clock track and servo tracks on one or more of the fixed discs of a fixed disc magnetic disc drive without the aid of a mechanical head positioner; and which is also capable of writing a closed clock track and servo tracks (either on a dedicated disc...http://www.google.ca/patents/US4531167?utm_source=gb-gplus-sharePatent US4531167 - Servowriter system for magnetic disc drives
