TESTFDC usage

HP used them _a lot_, bot hthe signle-head and double-head versions. AFAIK they were actually 80 cylinder drives, with the normal 135tpi spacing. Certainly on the double-head ones, HP formatted 77 user cylinders, the last 3 were reserved for replacements for bad blocks, the bad block map, etc. There as a later Sony drive, also 600rpm, that HP put in the 9114B and, IIRC, 9153. This is a half-height unit, with many parts in common with the Apple 800K drive (head carriage, stepper motor, motor control ICs, analogue ASIC, etc). The version that HP used has a single 34 pin conenctor, pinout very similar to an SA400 (and thus a PC drive), but with power on some of the odd-numbered pins. But from the scheamtics, it's clear that moving soldered links would make all those odd-numbered pins ground, and there is a place on the PCB for a normal 4 pin power connector. Be warned that the oldder, full-height models have a nasty problem. The grease on the eject mechanusm goes hard with age, and this then doesn't latch properly,. On a double-head drive, the upper head can then get caught in the disk shutter when you eject the disk. It's possible to rip the head right off the gimbal spring. If you have one of the older drives, you might want to look for the recent articles about erparing the HP9114 drive on the forum at http://www.hpmuseum.org . There's a link from one of them to a document on repairing the 9114, the last part of that docuemnt is an article I wrote on taking the drive apart and cleaning off the grease. -tony