Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

HxC Floppy emulator support for all others computers...
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jgrant911
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Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by jgrant911 »

I Have an HxC SD Rev C that I am trying to configure for my California Computer Systems S-100 System. The Disk Controller is a CCS 2422 equipped with 2 Shugart 800/801 8" floppy drives. The fact that the media for these drives is starting to fail and new replacement floppies are not available is what led me to the HxC as a floppy drive replacement. My problem is described below:

- My HxC Emulator has HXCFE_V1_8_2_40.upd installed.
- The HXCSDFE.CFG as described below was created and copied to the 2GB SD Card
- The HxC is receiving the correct 5V power.
- The HxC is configured as Drive C: and connected to the floppy controller with a "twist" 34 pin cable as shown in the photo below.

Display.jpg
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Currently I am struggling with the procedure to get the correct data onto the HxC SD Card so that the CP/M OS (via the 2422 controller) recognizes the HxC and allows me to write/read files on it. The issue is, I am not familiar enough with the HxC configuration software to be sure I am doing this correctly.

In particular I need to define a SSSD Boot Disk image on the HxC that conforms to the IBM 3740 Standard for 8" floppies as implemented for the CCS 2422 Controller. The parameters are listed below:

Disk Format.jpg
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I have used the HxC software on my Windows PC to edit HxC files in an attempt to do this. I used the SD HxC Floppy Emulator Settings button to configure this as shown below left and save the HXCSDFE.CFG file to the SD Card. I also used the RAW File Format Configuration screen (below right) to create an SSSD.FPF config file and an EmptyFloppy.HFE file and copied these to the SD Card.

Emulator Settings.JPG
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When I power up the computer, the HxC SD Card Access lights up and the display is as shown in the photo. When I try to access the Floppy Emulator as C: drive (DIR C: or STAT C:) the Floppy access LED lights up but nothing else happens and I have to Reset the computer.

That's where I am right now. I am not clear on the relationship between the two configuration screens above so it is very likely that I have not configured the SD Card properly. Any pointers in getting that right are appreciated.

Once I get the basic SSSD configuration I will hopefully be able to define SSDD and DSDD configs. The ultimate goal is to create a mixed density Boot disk: CP/M requires all boot disks to have the first track formatted as 128 byte Single Density sectors to comply with the IBM standard and to allow the CCS BOOT ROM to automatically read the bootstrap loader from this track. Remaining tracks can be formatted at a higher density.

I hope someone can point me in the right direction.

Cheers!

Jim

jgrant911
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by jgrant911 »

Update:

I fiddled with the floppy configuration parameters and eventually came up with a variant that the CP/M OS didn't barf on. Using the Generic Shugart mode and basic single density parameters for an 8" floppy I created an Empty Floppy HFE file and copied it to the HxC SD Card (see photos). I made sure the Empty Floppy was selected on the HxC screen and then tested.

Config.JPG
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Config1.JPG
Config1.JPG (46.87 KiB) Viewed 4186 times

With the HxC connected as Drive C: I booted up the computer to the CP/M A> prompt. I typed:
DIR C: and got back
NO FILE

Then tried:
STAT C: and got back:
Bytes remaining on C: 81K (a very low number for an empty floppy, even a SSSD 8" floppy should hold about 250KB)

I did try copying files to the C: drive with:
PIP C: = A:FILE.XXX and got back:
NO DIRECTORY SPACE: = A:FILE.XX (so something in the empty floppy format doesn't allow for directory space)

Other slightly different configurations I tried gave me no better result or no response at all (required a reboot).

So, a step forward. Obviously there is enough structure in this "empty" floppy for CP/M to interact with, just not in the right configuration to work correctly.

Unfortunately I am feeling like one of those infinite number of monkeys typing on keyboards, waiting for the works of Shakespeare to appear. Without a little nudge in the right direction this could take a long time!

Cheers!

Jim

Jeff
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by Jeff »

Have you tried to initialize / format the image from the machine ?

jgrant911
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by jgrant911 »

Jeff,

Yes, I tried that yesterday when I has testing the configuration above. Here's the dialog:

A>CCSINIT

CCS DISK FORMATTER PROGRAM V2.0
WHICH DRIVE (A-D)? C
SINGLE OR DOUBLE SIDED (0 OR 1)? 0
SINGLE OR DOUBLE DENSITY (S/D)? S
TRACK NUMBER (0-4C OR *)? *
SECTOR SIZE (0-3)? 0
IS IT A MINI (Y/N)? N

INIT ERROR: DRIVE C; SIDE 00; TRACK 00; SECTOR 1A; STATUS-06

I am not sure what the error code means but I have attached the 1793 Status Register Summary:

1793 Status1.jpg
1793 Status1.jpg (89.19 KiB) Viewed 4165 times
Thanks,

Jim

Jeff
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by Jeff »

please share the hfe after the format attempt.

jgrant911
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by jgrant911 »

Jeff,

The forum won't allow the file to be attached (too big, wrong type). I have emailed it to you.

I did do a file compare and there are definitely some differences between before and after.

Jim

jgrant911
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by jgrant911 »

Jeff,

It's curious that the INIT ERROR is at sector 1A of the first track. According to my info there are 1A (HEX) sectors per track so this should be a valid track (sectors count from 1 to 1A = 26 which is what the sectors per track is set to).

Jim.

Jeff
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by Jeff »

jgrant911 wrote:
Sat Dec 03, 2022 4:35 am
Jeff,

It's curious that the INIT ERROR is at sector 1A of the first track. According to my info there are 1A (HEX) sectors per track so this should be a valid track (sectors count from 1 to 1A = 26 which is what the sectors per track is set to).

Jim.
Are you sure about the format specifications ? 128 bytes 26 sectors FM sectors can't fit on a 300RPM (200ms) or 360RPM (166ms)disk at 250kbits per seconds (data + clock bits)
you can inspect the disk/track state in the "track analyzer" windows

Please try to format / init all the images i have just sent to you and send me back them.

jgrant911
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by jgrant911 »

Just an update in case anyone is following these posts:

Jeff and I have exchanged many emails trying to sort this out. I have been using my digital scope and logic analyzer to examine the signals coming from the HxC including Head Load, Index and Read Data. The latest step was to capture the data for several revolutions of the boot process from one of my Shugart floppies and forward this to Jeff. Apparently he is able to examine and decode this data stream and should be able to create an hfe file that can respond properly to my disk controller.

Hopefully this will happen soon and I can begin transferring my floppy disks onto SD Card so I won't be in fear of all my 40 year old floppy disks deteriorating into unreadability!

Cheers!

Jim

exidyboy
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by exidyboy »

Looking forward to an update on this as I will also eventually need to be able to boot an Exidy Sorcerer from a mixed format 5.25 inch disk upon which the first track is FM. (Also wondering if the CPC EDSK format supports this).

Jeff
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by Jeff »

exidyboy wrote:
Sun Feb 19, 2023 3:05 am
Looking forward to an update on this as I will also eventually need to be able to boot an Exidy Sorcerer from a mixed format 5.25 inch disk upon which the first track is FM. (Also wondering if the CPC EDSK format supports this).
Many formats support this : IMD, EDSK, D88, HFE, ...
And the HxC emulator is used on many PC98 machines using this mixed track format/density.

The problem here is different and probably no directly related to the image format.

jgrant911
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Re: Can You Help Me Configure HxC SD for S-100 CP/M 8" Format

Post by jgrant911 »

OK, thanks to much help from Jeff and members of the Google S100Computers group, I now have my HxC working on my S100 system. I will try to summarize the problems and their solutions below.

1. Recall that my computer is a 1980 vintage S100 bus computer with 8" SSDD Shugart drives. Relevant drive characteristics are:
- 77 tracks with 360 RPM rotation rate
- Track 00 format: SD 128 bytes x 26 sectors (250 kHz FM data rate)
- Track 01-76 formatted DD with bytes x sectors = 256 x 26, 512 x 15 or 1025 x 9 (500 kHz data rate)
This requires a dual density disk format HFE file that Jeff provided (based on a CP/M Boot disk image I got from an online associate).

2. I had my HxC connected to the 34 pin interface on the CCS 2422 drive controller (my 8" drives were are installed on the 50 pin connector). This led to complications that took time to figure out:
- The 1980 hardware and software would not decode a double-density (500 kHz) data stream on the mini-disk interface. I found this when I used a logic analyzer with an MFM decoder module to look at the signal that the HxC sent while reading the Boot disk image.
- I found from the CCS manual that the 2422 controller has circuitry that CP/M uses to specifically check which connector the drive is on. It then limits the Read Clock decode frequency to 250 kHz on the Mini interface (mini disks back in the day were only 250 kHz apparently).
- I made a minor modification to the controller board to fool this detection system. With that done I could successfully read files from the HxC.

3. The final problem arose when I tried to copy files from my 8" floppies to the HxC. I found that the read/write process between my Shugart 800/801 drives and the HxC was very unreliable. Attempting to copy any of my old floppies to the HxC resulted in a BDOS Error or there were serious errors on the resulting HxC file, almost every time. It turned out that there is some loading/signal conflict between the Write Data lines from the Shugarts vs. the HxC. I found that by removing one of the 8" drives from the interface that the interference was reduced and the 2422 controller was then able to provide a Write Data signal that the HxC could reliably interpret. I am still trying to isolate the root cause of this issue.

With reliable file transfers between my 8" floppy drive and the HxC my primary goals with the HxC are realized:
- I have now backed up all of my old CP/M software onto HxC virtual disk files and stored duplicate copies on my Windows PC.
- I can work with my S-100 system as often as I like without putting wear and tear on 43 year old floppies and drives.

***Important note: I realize now that it would have avoided much of this trouble if I had used one of the 30 pin to 50 pin drive adapter boards available on several enthusiast websites. Using one of these with the proper jumper settings would make the HxC "look like" an 8" drive and eliminated the long struggle caused by step 2 above!

I hope this info helps anyone struggling with a similar problem. If you want any of the specific details I am happy to provide them.

Cheers!

Jim

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