Help with low level format on Victor 9000

[Paul Devine]

I'm trying to do a low-level format on a Victor 9000, which is connected to the MFM Emulator via a Xebec s1410a running firmware 104788. The computer seems to connect correctly to the drive. Immediately after initiating the low-level format I get an error that reads

"Error: No index detected from disk drive. Possible failures are Drive, Status Control Cable."

I start the emulator and see some requests going across: 

root@beaglebone:~/emu# ./setup_emu
Rev C Board
root@beaglebone:~/emu# ./mfm_emu --drive 0 --file /mnt/emufile_c --cylinders 977 --heads 5 --initialize --quiet 0
Board revision C detected
Emulated drive RPM 3600
Drive 0 num cyl 977 num head 5 track len 20836
PRU clock 200000000
  Waiting, seek time 0.0 ms max 0.0 min free buffers 75
bad pattern count 0
Read queue underrun 0
Write queue overrun 0
Ecapture overrun 0
glitch count 0
glitch value 0
0:test 0 0
0:test 1 0
0:test 2 0
0:test 3 0
0:test 4 0
1:test 0 0
1:test 1 0
1:test 2 0
1:test 3 0
1:test 4 0
select 3 head 0

I'd love any advice for additional things I could try to debug the situation. I've checked the SASI termination, and the termination on the MFM board, as well as the write enable pin and drive selector pins. Everything seems in order. There's a separate utility to check the contents of the first sector where Victor stores boot loader information. That reads as a sector of all 0's, so it seems like it's able to read the drive. It appears to me for some reason the writing is hanging things. I tried a different 34-pin cable as I had one available. I didn't have a duplicate smaller cable but that's something else I could try.

Any guidance appreciated.

Thanks,

Paul

[David Gesswein]

On Sat, Feb 12, 2022 at 09:32:16PM -0800, Paul Devine wrote:
> I'm trying to do a low-level format on a Victor 9000, which is connected to
> the MFM Emulator via a Xebec s1410a running firmware 104788. The computer
> seems to connect correctly to the drive. Immediately after initiating the
> low-level format I get an error that reads
> "Error: No index detected from disk drive. Possible failures are Drive,
> Status Control Cable."
>
> I start the emulator and see some requests going across:
> root@beaglebone:~/emu# ./setup_emu
> Rev C Board
> root@beaglebone:~/emu# ./mfm_emu --drive 0 --file /mnt/emufile_c
> --cylinders 977 --heads 5 --initialize --quiet 0

You probably don't want --drive 0. For normal use use --drive 1 then set
P7 for desired drive select.
http://www.pdp8online.com/mfm/code/emu/mfm_emu_doc.html

Little supprised you would get no index detected since --drive 0 should
have had the drive always selected.

If that doesn't help the signal sequence is computer will drive low one
of the drive selects. The emulator will drive pin 1 low on J1 and start
generating index pulses on J2 20 at 60 Hz rate.

Since you think its related to write you can trigger on write going low
and verify index is still present.

https://en.wikipedia.org/wiki/ST506/ST412

[Paul Devine]

Thanks for the quick response. I should have explained, I tried disk 1 first and had the same issue. I went to disk 0 just incase I was doing something wrong with the drive jumpers. I'll check things with a logic analyzer and see if I can deduce what's happening.

[Paul Devine]

Wanted to report my success back here. So I needed to replace a bad capacitor on the SASI board in the Victor. After doing that I was able to format the MFM Emulator and install MS-DOS on it. So I have a working Victor 9000 disk image if that's helpful to anyone.

[Paul Devine]

Also, should have started with a HUGE thank you to David. Thanks so much for all your great work in providing such an elegant solution. Truly thrilled to have a working hard drive.