ISA bus throughput

Not easily. You don't, of course, get the raw head connections at the interface connecotr, there's a write (recoding) driver and a read (playback) amplifier in the drive. These circuits are strictly digital (the interface signals are actually at RS422 levels IIRC). And there are resrictions on the frequency of the pulses you can record (both minimum and maximum from what I rememebr). And of course, sioce the drive rotates at something like 3000rpm, you'd only get a recording time of 1/50 of a second per track. I do have a video hard disk in my collection. This is a head-per-track hard disk rotating at 3000 rpm, such that 1 frame of TV video can be recorded on each track. It uses FM (analogue) modulation to do this. There are 3 indentical read/write circuits to handle RGB colour. I am told that this sort of disk was oringinally designed for TV action replays. The one I have has a DAC on the input to the FM modulator, with a Unibus interface (via a DR11-B) on the front of that. -tony