HP82901M Disk drives

This was a gift from Rik Bos (thanks a lot, Rik!). It is a HPIB disk pair suitable for several HP machines.

I want to try to use this with my 9825A, because I have an HP/IB adapter for that, plus the SSS ROM (which I got from Adrian, thanks a lot!!).

Getting the SSS Rom to work

The first challenge: the ROM module did not work. None of the commands that should be present with the SSS Rom connected worked, all of them reported error 3 meaning they were not recognized.

I got the schematics for the module from Paul, and the manual from the HP museum. Opening the module showed the problem: the address decoder PROM was not installed. I bought a new 82S129 on EBay and programmed it with my new Stag Quasar programmer - and that fixed that problem.

Trying the drives

I tried to format a diskette using the init commands for both drives:

init 701
init 702

The first one, for the first drive, did do something: it played with the drive for about 3 minutes but after that it reported a D9 error which is “verification failed”.

The second one reported a D0 most of the time, but sometimes something else. Time to open up the box

The drive box opened. The controller board is at the right with the MC6802P, the MB8866 floppy controller and the D8291 talker/listener; one drive lies removed at the left.

The control board uses an MC6802P processor, a MB8866 floppy controller and the D8291 GP/IB Talker/Listener.

The floppy drives are HP 9130K drives.