Wanted: STDC

[Mike Loewen]

   I had my Z2 up and running Cromix-Plus 31.68 last week, from Dave Gesswein's MFM emulator. I had some occasional problems with the system hanging, apparently waiting for the disk to respond. The problem started getting worse, until accessing the hard drive only works for a minute or two. To eliminate the MFM emulator, I attached a physical hard drive, with the same result. When this occurs, everything else seems to be working, keyboard input is still accepted, but the commands can't be interrupted.

   So, it looks like I need another STDC. Does anyone have one for sale?

   Or, is there another mass storage option? I already have a pair of Goteks attached.

[Jay Cotton]

I have what looks like the same issue.

Booting UNIX or Cromix from the MFM emulator hangs in what looks like waiting for the disk/controller to do something.

I obtained a second STDC but it shows the same problem.

My conclusion is the XXU card has a fault.  I removed the XMU and the bug is the same.  The other interesting thing

is I have a 4mb static ram board (s100computers) and at the time that these bugs showed up, the static ram stopped 

working with the machine at all.  I am now using a 1meg ram board. 

I can boot Cromix from a floppy image and mount the Cromix partition.  This works without error as far as I can tell.

I have been looking at the interrupt circuit on the XXU, I am not convinced it has any problems however.  I currently suspect 

an address line as the fault.  

Needless to say, I am a bit reluctant to just change a part.  Need to verify the fault before pulling chips.

I am interested if you can boot Cromix from a floppy image (627) and then mount the hard drive (partition 2).  Perhaps you have

the exact same bug that I do.

tnx

JC

[Jay Cotton]

I should point out, if its not clear.  I was able to boot and run unix from the hard drive image

on the MFM emulator, and I demoed that at VCF west about 2 years ago.  Somehow I busted the

machine and I am still trying to figure it out.

jc

[Mike Loewen]

My setup has a 64FDC, DPU, 4MG Static RAM, IOP/QUADART and STDC. I've substituted the original pair of 256KZ boards for the 4MG RAM, and the problem remains. When I boot from floppy (Gotek) and try to mount the hard disk image, the problem is the same. I'm thinking that the STDC has a thermal problem. As I said, this was working last week, but has been getting progressivly worse. The system works quite normally when booted/rooted on the floppy image.

[Mike Stein]

Do DISKINFO & READALL show anything useful?

--
You received this message because you are subscribed to the Google Groups "Cromemco" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cromemco+u...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/cromemco/057d0463-73b9-4011-935e-9bb992c5bfd3n%40googlegroups.com.

[Mike Stein]

No issue with the interrupt chain cable?

I'm out of town at the moment so I can't easily confirm, but in case you're not aware IIRC they swapped In/Out at revision D; D and later should be the same as the FDC, i.e. right to right & left to left

On Sat, Feb 22, 2025 at 9:05 AM Mike Loewen <jaz...@gmail.com> wrote:

--

[Richard Muse]

Just another thought. I was having a similar issue with STDC's in both the XXU machine and one of the System Two's. I found that removing the board and re-seating all of the socketed chips resolved both. In my case, one was with a physical hard drive, the Sys Two, and the other with David's emulator.

Richard

To view this discussion visit https://groups.google.com/d/msgid/cromemco/CAHHfo1ucPAYAqXLtV18QUNvnPq3Hgmhc39FwqkpDxExP-EjOLQ%40mail.gmail.com.

[Mike Loewen]

   I've had some success with the STDC this afternoon. My board appears to be a Rev. D, Mod level 11. However, the J2 wiring does not appear to be reversed. Looking at the component side of the board, with the S100 connector at the bottom, the yellow dot is on the left side of J2. If I connect the priority out from the previous board to that pin, I get "unexpected interrupt vector" messages. The priority IN on my STDC is the right-hand pin. The STDC-D.TXT document on github only goes up to Mod Level 10.

  Yes, I had reseated all the socketed chips on the STDC.

   I ended up removing the IOP and QUADART boards and jumpering the priority cable directly from the 64FDC to the STDC. I was successfully able to use DISKINFO, READALL, MAKFS and MOUNT, as well as root the OS on std0 after booting from floppy. Moving forward,I'll continue to attack this as an interrupt issue.

[Mike Stein]

Sounds good; rev C and earlier were the opposite, i.e. IN on the left.

The FDC is the only other board like that, all the rest are Out (L) to In (R).

The Quadart is not part of the chain; IIRC there's a jumper plug that needs to be wired but I think that's for the address.

To view this discussion visit https://groups.google.com/d/msgid/cromemco/620ac64b-ad5d-492c-9acd-efa91e011426n%40googlegroups.com.

[Mike Loewen]

   I believe my problems were caused by connecting the interrupt priority cable through the QUADART. There's a connector there for priority in and out, which I mistakenly assumed was in the same chain as the other boards. According to the QUADART manual, that's for prioritizing interrupts for multiple C-Bus devices. I have the IOP and QUADART both plugged in now, with the interrupt cable going from 64FDC -> IOP -> STDC. Everything is working fine.

   Next step is to get the QUADART working with Cromix. I'll create another thread if I need help.

  Thanks, guys!

[Mike Stein]

Glad I could help for once ;-)

To view this discussion visit https://groups.google.com/d/msgid/cromemco/939ae6f1-c381-4fb7-b052-9bc9ec7a614dn%40googlegroups.com.