Wanted: Exidy Sorcerer CP/M

[dutchacorn]

While on the subject of FDS, I made a quick scan of two related documents; the FDS Operators Manual and the Disk Utility package documentation. They can be (temporarily) downloaded from my dropbox here: https://www.dropbox.com/sh/2t2c2qxkv...r6l2fo5Ta?dl=0.

If anyone can place them on a more permanent hosting location that would be great...

[exidyboy]

While on the subject of FDS, I made a quick scan of two related documents; the FDS Operators Manual and the Disk Utility package documentation. They can be (temporarily) downloaded from my dropbox here: https://www.dropbox.com/sh/2t2c2qxkv...r6l2fo5Ta?dl=0.

If anyone can place them on a more permanent hosting location that would be great...

Thanks for posting those. Very interesting to see more documentation saved. The Disk Utility manual seems to be for hard-sector software while the FDS Operators Manual for soft-sector.
Bitsavers for would be a good place for them if we can catch the attention of the very busy Al Kossow.

[exidyboy]

There were two variants as far as I know:
DP6400: 40 Tracks, 48 TPI
DP6402: 77 Tracks, 100 TPI

Yes you can see it is a DP6402 in the photos I posted above. I have been poring over all references to Micropolis in Sorcerer newsletters and it looks like the 100TPI drive can be hooked up to some of the later Australian-developed disk controllers so it must have a standard interface although this wouldn't 'image' the disk. But it also suggests electrical compatibility with standard drives.

One newsletter reference suggested that the Exidy FDS might be the only system that ever used 100TPI soft-sector geometry.

[exidyboy]

You need a 100 tpi disk drive to do it correctly.

I've been loaned a 100TPI Micropolis drive and have around 10 soft-sector disks to image.
Many are unfortunately Control Data brand which in my experience do not age well but these discs are from Tasmania where the climate is cooler and drier so perhaps there will have been less binder breakdown.
If successful AFAIK this will be the first time that CP/M 2.2 for the Exidy FDS has been preserved.

[exidyboy]

If you are lucky the drive is fitted with a “floppy disk subsystem add-on”. It would have a cable to connect a second unit:

Attachment 53175

You should then be able to connect a 80T 96TPI drive as a second drive and copy cpm 2.2 to that.

Is the blue cable in the photo the one that attaches to the second "add-on" drive while the male header attaches to the 50 way expansion connector via a straight through cable?
What physically is the "floppy disk subsystem add-on" - another internal PCB within the disk drive enclosure?

[dutchacorn]

Is the blue cable in the photo the one that attaches to the second "add-on" drive while the male header attaches to the 50 way expansion connector via a straight through cable?
What physically is the "floppy disk subsystem add-on" - another internal PCB within the disk drive enclosure?

Yes, the blue cable is for the second drive.

The floppy disk subsystem add-on is nothing more than a second drive in the same enclosure as the DP6400. No PSU, no controller card. It takes power from the DP6400 through a separate cable.

I hooked up an HxC floppy emulator to my DP6400 and copied the CP/M 2.2 system disk to an image. It's 40 tracks, 512 bytes per sector, 8 sectors per track (160KB).

See here for the image. The hfe is the native HxC format, the img is an export to a raw sector file format.

[exidyboy]

I hooked up an HxC floppy emulator to my DP6400 and copied the CP/M 2.2 system disk to an image. It's 40 tracks, 512 bytes per sector, 8 sectors per track (160KB).

Interesting. This price list claims the DP-6400 is 77 track.
http://www.bitsavers.org/pdf/exidy/b...st_May1980.pdf

[dutchacorn]

Interesting. This price list claims the DP-6400 is 77 track.
http://www.bitsavers.org/pdf/exidy/b...st_May1980.pdf

According to the Operators Manual (page 11) the 77 tracks version is the DP6402.

[exidyboy]

OK. The 77 track unit I have here on loan (with the broken bezel that I am searching for a replacement for ) says it is DP6400-2

I converted your .hfe to a .dsk using samdisk and did a scan:

Macintosh-3:samdisk-388-osx mb$ ./samdisk scan exidy.dsk[exidy.dsk]
40 Cyls, Head 0:
250Kbps MFM, 16 sectors,  256 bytes/sector:
  0.0  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
250Kbps MFM, 10 sectors,  512 bytes/sector:
  1.0  1 2 3 4 5 6 7 8 9 10
  2.0  3 8 2 5 10 4 7 1 6 9
  3.0  1 2 3 4 5 6 7 8 9 10

etc ...

It thinks the first track is 16 sectors and the remainder are 10. The skewing pattern reported on cylinder 2 (only) is different to the others.

Note there is evidence that Compudata used a different geometry to Exidy.
Perhaps the boot track is the same to maintain compatibility with the FDS controller board under the drive then they might have done their own thing on subsequent tracks to get higher capacity. I also wonder if they made their own controller PCB's in The Netherlands using Exidy's artwork?

[dutchacorn]

The CP/M 2.2 is distributed by Compudata. I don't see any references to Compudata on the disk drives.

The operation manual mentions that the capacity of a formatted disk for the 40T drive is 160K ("dual density").

The EXFORMAT program supplied with the CP/M 2.2 provides the option to format using 256 bytes per sector or 512 bytes per sector, the 512 bytes resulting in approximately 25% more space (according to the EXFORMAT help text). So either CP/M can't use the extra space efficiently or the 512 bytes/sector format uses fewer sectors per track.

All my CP/M 1.4 disks are formatted 256 bytes per track, all the CP/M 2.2 disks use 512 bytes per track.

A freshly formatted disk formatted 256 bytes/track reports 148KB using STAT, a 512 bytes/track formatted reports 186KB capacity using STAT.

So it's all very confusing. The image was created by creating a blank image using 40T, 8 sectors, 512 bytes per sector, and then formatting it on the Sorcerer in the HxC. Apparently the HxC floppy emulator is a bit flexible on the number of sectors per track...