Z80 Cromix, 256KZ and 64FDC mod

[Mike Loewen]

   I've been trying to get Z80 Cromix 11.27 running, and have a problem similar to one described on an earlier thread. Hardware: DPU, two 256KZ boards configured for Z80 with PROMs 74948 and 74949, 64FDC with pin-69 mod, IOP/QUADART and STDC, twin Goteks.

   When booting off images 674C1127 or 676C1127, all looks good until prompted for the root device. If I enter 1 (Floppy) and 0 (minor), the process just stops. The same thing happens if I choose a STDC partition with the 11.27 filesystem copied over.

   I did the S-100 pin-69 mod to the 64FDC for working with the 4MB static RAM board, which is not currently installed for Z80 Cromix testing. Is that mod compatible with the 256KZ boards? I have the same problem when using a single 256KZ board with the 74947 PROM installed.

  Suggestions?

[Jay Cotton]

Try floppy (1) and (4) minor device.

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[Richard Muse]

The pin 69 mod will not affect operation with the 256kz boards. Cromemco does not use pin 69 for anything.

Richard

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[Mike Loewen]

   I'm stumped, then. Trying minor device 4 doesn't change anything - those disks are large format anyway. I've also tried Roger Hanscom's CRMX.DSK with the same results.

[Mike Arnold]

I am sure that you have thought of this already, but back in the day it was "strip it all back" and then build it up again. Try DPU, 1x266kz, FDC and boot with CDOS. Run diskdiag to ensure that the CDOS image verifies ok then verify the Cromix image under diskdiag. If all fine then try booting Cromix. If it still works then start to put in the other boards one at a time.

If you have a physical drive and a floppy disk that will help you build confidence about the function of the Gotek.

[Mike Stein]

Did I miss something? Is there a hard disk or emulator connected

to the STDC? I assume you don't have a 'real' floppy drive of any kind?

Roger was kind enough to send me his files; guess it's time to finally take my Gotek out of the box and see if I can get this running.

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[Mike Loewen]

 I do have a Gesswein MFM emulator attached to the STDC. It works fine with Cromix-Plus 31.68. I did find that one of my 256KZ boards has a problem. I cut back to a single 256KZ with the 74947 PROM and it tests ok for all 4 banks under RDOS 3.12. With a single (presumed) good 256KZ, booting 11.27 now gets past the major/minor root filesystem prompt, but then complains that it is unable to read the super-block on the boot floppy (Gotek image).

   I removed all other boards except the DPU, 64FDC and 256KZ and get the same result.

   Just for grins, I removed the 256KZ and put the 4MB RAM back in and booted from the 11.27 image. This setup allowed me to select the root filesystem on the floppy and (almost) completed the boot process. As expected, it reports "All Memory in Use", because the 4MB doesn't do bank switching.