Servo Demodulation on Double-Sided Flexible Disk Using Single Demodulator
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
A disk file track-following servo system uses servo information recorded on both surfaces of the disk by time sharing the servo demodulation circuitry. On a double-sided file where only one read head is used at a time, there arises the problem of what to do with the unused head/arm; i.e., should it be detented where it is with some type of magnetic clamp, or, should it be returned to the guard band while the other head is in use. Both of these methods pose problems of recovery to a controlled state when that head is needed, thus using up time in getting access to data under that head. One solution is to have two servo loops in operation all the time controlling each head/arm. The main disadvantage with this method is the unnecessary duplication of hardware.