SCSI floppy on the HP 9000/735

Started by jmetal88, July 29, 2017, 09:26:51 pm

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Hey everybody,

I'm brand new to NeXTSTEP and I've just recently installed it after upgrading my HP 9000/720 to a 9000/735 configuration by replacing the CPU and I/O cards.  I'm already aware that the 'Wide SCSI' interface isn't supported, but since I only have 'Narrow SCSI' drives, I figured that wouldn't be a problem.  However, my 720 came with a floppy drive, and I cannot figure out how to get it to work in NeXTSTEP.  NeXTSTEP can clearly see the drive, as it shows up during the SCSI probe in the verbose boot as a 'TEAC FC-1' (it's actually a TEAC FD-235HS, but does seem to identify itself to the system as an FC-1 no matter what OS is running).  The first message says it was detected as 'sd2'.  But the message showing the list of drives found right afterward omits it from the list.  Trying to access any of the 'sd2' devices in /dev/ after a boot gives results that appear to indicate there is no such device installed.

One behavior that I thought was interesting is that, when you probe for disks from within the GUI (or when the system probes on boot and on login), if a disk is not inserted in the floppy drive, the activity light will flash.  But if a disk is inserted, the activity light stays dark.  I've used the drive successfully in HP/UX before (they never seemed to add GUI support for it so it was only accessible via command line utilities), so I'm pretty sure it's not broken, but I just don't seem to be able to get NeXTSTEP to do anything with it.

If this just isn't supported in NeXTSTEP I suppose I just won't worry about it, and since I have networking set up I can do file transfers that way without having to waste any CD-Rs, it's just that I have the floppy drive in the system already and I don't have any type of cover I can put in place if I remove it, so it just seems weird to have an OS installed that can't make use of it.


Well, just as a sanity check, I put a different hard drive in the machine and installed HP-UX...  And I can't access the floppy from it, either.  Though it's at least telling me it's having read errors and not just pretending there's no drive there.

Guess I need to attempt some drive repair.  Once I have it working in HP-UX I'll try NeXTSTEP again.


Beware that this is not a standard floppy mechanism.  It has a custom connector pinout that provides power to the floppy-to-SCSI adapter that it is mounted in.

I found out the hard way when I attempted fixing my 9000/715XC and plugged the floppy mechanism into a "standard" PC for troubleshooting.  Thankfully I was able to determine that all that happened is a 000 "resistor" (aka jumper) on the power line of the floppy mechanism burned out and I was able to replace it.  I also spent an insane amount of time talking to TEAC about calibration, etc.  In the end I collected a bunch of DOS utilities for floppy calibration and I was able to get the drive to a working order with a known good "reference" floppy disk, as opposed to a TEAC calibration floppy, and with an analogue oscilloscope...

But I do not believe NS for HPPA can access the drive as a floppy, if my memory serves me right.  It has been around five years...

TEAC were amazing, by the way - I got to talk, via email, to the head of their floppy design engineering in Japan!


Well, the first time I had it working I had to replace three capacitors on it, so I just ordered a full kit of electrolytics and hopefully that will take care of the issue.  Would not surprise me if additional capacitors went bad, and honestly since my original replacements were 'salvage' capacitors, they could've even gone bad by now.

I did not try this drive in a PC, but I did try a PC drive attached to the SCSI converter, and well, that would explain why nothing happened when I did so, haha.


Finally figured out I was doing something wrong in HP-UX (after I replaced a few more capacitors on the drive, of course).  HP-UX needs the "scsifloppy" driver loaded in order to access the drive (which I already knew and had added it to the kernel) but what I failed to realize is that the character device needed to access the drive as a floppy was different than the character device needed to access it as a SCSI drive.  So using /dev/rdsk/c201d5s0 was simply not working, however /dev/rfloppy/c201d5s0 did not exist.  But I used an ls -l on /dev/rdsk and /dev/rfloppy to find the parameters I needed to pass to mknod in order to create /dev/rfloppy/c201d5s0.  And what do you know, success!  I can read my DOS floppies!

Unfortunately, the drive STILL doesn't work in NeXTSTEP, and I think it is because NeXTSTEP is missing that scsifloppy driver that I had to load on HP-UX.  After some more searching, I finally found some confirmation here:

"1.44 MB floppy disk drive is supported on the 712 workstations. SCSI floppy is not supported on the 7X5 workstations."

So, yes, trying to get the floppy on my machine to work in NeXTSTEP is a wasted effort.  That's too bad, I would've liked to have had it usable.