Re: Help please: Cromemco Z-1 with PFD
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Michael Leon Peterson
Aug 18, 2011, 11:11:03 AM8/18/11
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Martin,
I have not yet received the 5.25 CDOS 2.58 disks from Marcus yet, but I was
able to create working 5.25 and 8 in CDOS disks using RDOS and Dave’s
process. I had to make changes to my 64FDX and also use the process of
downloading RDOS 2.52 since the RDOS on the 64FDX was 3.12 it would not work
with Dave’s utilities at all, it would just hang. 
So I can mail to you a SS SD 5.25 CDOS 2.58 if you are still in need of
that. The 8 inch is another issue, I can make DS SD but not a SS SD, the
index hole on my 8 inch diskettes do not allow the SS SD. I have only few
of those 8 inch that have that both index holes with the label “Single
–Sided/Double-Sided” that have original Cromemco software on them that so
I do not what to change them to Single-Sided by move the sticker.
If you want to provide a SS SD 8 inch diskette that would work for
me. Let me know what you want to do. If you still need the bootable
5.25 CDOS 2.58 SS SD, I can mail that to you.
Michael
From: MICHAEL_...@MSN.COM
Sent: Thursday, August 11, 2011 7:56 PM
Subject: Re: Help please: Cromemco Z-1 with PFD
Martin,
As soon as I get my 5.25 CDOS disk from Marcus I will be able to create
additional 5.25 and 8 in for you and provide that. I am expecting them to
arrive next week, Mon or Tue.
I would expect the issues to be more with the Persci 277, rather than the 4
FDC, the heads on those will wear and the response goes away. I used to
repair those by replacing the heads even on 299. What version of CDOS are
you using?
Michael
From: Martin Eberhard
Sent: Thursday, August 11, 2011 5:11 PM
Subject: Help please: Cromemco Z-1 with PFD
Well,
time to stop lurking...
I am bringing up a Cromemco Z-1 with a Cromemco PFD disk drive, and I have reached the point where I could use a few hints from Cromemco experts.
I have debugged and repaired the Persci 277 disk drive using a Processor Technology Sol 20/Helios II, and the Processor Technology SIMU software. The drive now seems to work correctly on the Sol 20. There a couple of dozen jumpers that must change when moving a Persci 277 from a Helios II environment to a Cromemco environment. I have moved them over for the Cromemco. (If anyone's interested in the Persci 277 jumper changes, let me know.)
Again, after a fair bit of cleanup and debugging, the Z-1 seems to work correctly at 2 MHz and 4MHz, though I have not tested it extensively. The following boards are installed:
(1) Cromemco ZPU
(4) Cromemco 16Kz
(1) Cromemco 16FDC
When connected to a Wyse WY-30 terminal (which I designed :-) ), RDOS 2 comes up and seems to work as advertised.
Lots of Cromemco software seems to be available in Image Disk format (.IMD), so I got a copy of Dave Dunfield's Image Disk software. I hacked up an old Dell PC to be able to read/write both a Shugart SA850 and an old 360K 5.25" drive. (John Wilson's FDADAP board works great for interfacing to 8" drives.) Image Disk seems to work with this setup - I can write files to a floppy and read them back correctly. Further, I can write 8" disk images for CP/M and read them correctly on one of my CP/M machines.
I pulled several images of Cromemco CDOS disks from the web, in Image Disk (.IMD) format. Rumaging through, I found several CDOS images that were for 8" disks, and were single-sided, single density. I also found a few single-sided 5.25" images.
When I attempt to boot CDOS using the Persci drives, I get poor results. CDOS comes up (sometimes), but I can't always read the directory, and I often get "Read-after-write" errors. Executing STAT seems to trash the disk. I note that CDOS complains if I remove the write-enable tab from the disk.
I suspect that the problem is the disk controller, not the drive. I switched to a known-good SA400L drive, and attempted to boot a 5.25" CDOS image - no luck. with this drive, I never got to the CDOS prompt - after trying several CDOS images. However, I can successfully and reliably read individual sectors and sequences of sectors using RDOS commands. This is true for both single-density and double-density tracks.
I put a frequency counter on the 16FDC data separator and tuned it to 500.46 KHz. (it was a little out of spec.) No luck.
So here are a few questions:
1. Does CDOS write to a floppy during normal operations like DIR and STAT? Or is the read-after-write error a symptom of a larger problem, like a bad CDOS load that is executing garbage?
2. Can someone point me to a known-good single-sided 8" CDOS image? Also a single-sided 5.25" image would be nice.
3. Even better, would someone snail-mail me a single-sided CDOS disk?
4. Any advice on debugging the 16FDC? What should I be looking for?
This Z-1 will be a sweet machine when it's done. It's now in great shape, and the walnut cabinet of the PFD is gorgeous. Your help restoring this machine is appreciated.
Thanks!
Martin
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I am bringing up a Cromemco Z-1 with a Cromemco PFD disk drive, and I have reached the point where I could use a few hints from Cromemco experts.
I have debugged and repaired the Persci 277 disk drive using a Processor Technology Sol 20/Helios II, and the Processor Technology SIMU software. The drive now seems to work correctly on the Sol 20. There a couple of dozen jumpers that must change when moving a Persci 277 from a Helios II environment to a Cromemco environment. I have moved them over for the Cromemco. (If anyone's interested in the Persci 277 jumper changes, let me know.)
Again, after a fair bit of cleanup and debugging, the Z-1 seems to work correctly at 2 MHz and 4MHz, though I have not tested it extensively. The following boards are installed:
(1) Cromemco ZPU
(4) Cromemco 16Kz
(1) Cromemco 16FDC
When connected to a Wyse WY-30 terminal (which I designed :-) ), RDOS 2 comes up and seems to work as advertised.
Lots of Cromemco software seems to be available in Image Disk format (.IMD), so I got a copy of Dave Dunfield's Image Disk software. I hacked up an old Dell PC to be able to read/write both a Shugart SA850 and an old 360K 5.25" drive. (John Wilson's FDADAP board works great for interfacing to 8" drives.) Image Disk seems to work with this setup - I can write files to a floppy and read them back correctly. Further, I can write 8" disk images for CP/M and read them correctly on one of my CP/M machines.
I pulled several images of Cromemco CDOS disks from the web, in Image Disk (.IMD) format. Rumaging through, I found several CDOS images that were for 8" disks, and were single-sided, single density. I also found a few single-sided 5.25" images.
When I attempt to boot CDOS using the Persci drives, I get poor results. CDOS comes up (sometimes), but I can't always read the directory, and I often get "Read-after-write" errors. Executing STAT seems to trash the disk. I note that CDOS complains if I remove the write-enable tab from the disk.
I suspect that the problem is the disk controller, not the drive. I switched to a known-good SA400L drive, and attempted to boot a 5.25" CDOS image - no luck. with this drive, I never got to the CDOS prompt - after trying several CDOS images. However, I can successfully and reliably read individual sectors and sequences of sectors using RDOS commands. This is true for both single-density and double-density tracks.
I put a frequency counter on the 16FDC data separator and tuned it to 500.46 KHz. (it was a little out of spec.) No luck.
So here are a few questions:
1. Does CDOS write to a floppy during normal operations like DIR and STAT? Or is the read-after-write error a symptom of a larger problem, like a bad CDOS load that is executing garbage?
2. Can someone point me to a known-good single-sided 8" CDOS image? Also a single-sided 5.25" image would be nice.
3. Even better, would someone snail-mail me a single-sided CDOS disk?
4. Any advice on debugging the 16FDC? What should I be looking for?
This Z-1 will be a sweet machine when it's done. It's now in great shape, and the walnut cabinet of the PFD is gorgeous. Your help restoring this machine is appreciated.
Thanks!
Martin
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Martin Eberhard
Aug 18, 2011, 1:20:58 PM8/18/11
to Cromemco
Hi Michael,
Thank you for the offer. But (per Bill's suggestion) I replaced the
WD1793 disk controller chip on my 16FDC, and everything suddenly
started working. I now can boot my copy of CDOS 2.54, which I created
using Image Disk. And using Cromemco's utilities, I can noe replicate
that disk, making further bootable disks. Cool :-)
Martin
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