Closed-clock writing system for a rotating magnetic memory

Abstract

A system is provided for recording a closed clock track on a rotating magnetic memory disc or drum. The system includes a temporary clock generating circuit for recording clock flux reversals in a temporary clock track on the memory, and a temporary clock reading circuit for sensing the flux reversals in the temporary clock track and for recording flux reversals at a higher frequency in a final clock track on the memory. The temporary clock generating circuit is automatically controlled to cause selected pairs of the flux reversals in the temporary track to be recorded at a certain frequency ratio to the flux reversal pairs in the final track, and to cause the remaining flux reversal pairs in the temporary clock track to be recorded at a different frequency ratio to the flux reversal pairs in the final clock track to avoid track closure error. The temporary clock reading circuit is automatically controlled to respond to the flux reversals in the temporary clock track which accrue at the first and second frequency ratios and still record the flux reversals in the final track at a selected constant higher frequency.