Wangco Model 82 5 - 1/4 " Floppy Disk Drive, Cromemco 4FDC S - 100 Controller, VGC
Item History & Price
This is a custom bundle being sold AS-IS due to age. Included are:Wangco Model 82 floppy driveCromemco 4FDC disk controller for the S-100 busMatching 34-pin ribbon cable6ea. 5-1/4" floppy disks previously used with this driveThis floppy disk subsystem is out of my IMSAI 8080, S-100 computer. Before selling the IMSAI, I tried to boot CP/M. I couldn't find a disk clearly marked as a CP/M boot disk. On startup, the drive select LED came on, heads engaged, and that'...s as far as it got.
This drive used to boot my CP/M, but It's been in storage for around 4 decades.
The 4FDC board has a modification shown in the pictures. I don't remember why. It most likely has a custom EPROM too. The assembler source for the EPROM might be on the floppies, or maybe on my 8" floppies that I'll be listing soon with the Calcomp drives and a Tarbell controller.
I don't know if these floppies are readable. I couldn't read them with a PC and a CP/M reading utility. I did read the DEC VT-180 (Robin) floppies that were stored in the same box as these IMSAI floppies.
I am listing these parts as a bundle in hopes someone can use the whole set. If you only need the drive or the controller, then message me. I am open to breaking up the bundle if it makes sense.
Please let me know if you have any questions. I'll do my best to answer, but please understand that I haven't touched this computer in about 40 years.
Item might be shipped by USPS, FedEx, or UPS. Quoted shipping cost won't change.On Jul-24-21 at 06:06:03 PDT, seller added the following information:UPDATE!!! I found the original RDOS 1.0 ROM for this board! My memory is still fuzzy but was improved by finding this chip. The Cromemco 4FDC board was shipped with the RDOS ROM which had boot & drivers for the CDOS operating system. I wanted to run CP/M not CDOS, so I wrote my own boot & drivers ROM. That's what's shown installed in the board. The original Cromemco RDOS ROM will be included with this sale. I haven't yet read it because I don't have a 2708 programmer. Might rig something up and will update.
Pictures follow. Note that the pins have some black goo because the ROM has been sitting in anti-static foam that decomposed.
On Jul-24-21 at 06:16:24 PDT, seller added the following information:Note: When I pulled the drive out of the case, one of the header wires was out of the header. I don't remember if this was a mod to deal with drive select or if it just slipped out. I put the wire back in the header. In case you will need this info later, I'm attaching a picture of how it looked when I took the drive out of the enclosure.
On Jul-24-21 at 06:18:55 PDT, seller added the following information:
On Jul-25-21 at 06:45:17 PDT, seller added the following information:UPDATE: I successfully read both my 2708 EPROM and Cromemco's ROM. I created a binary file of both and disassembled them. I can't for certain say all bits are correct because I have no original images to compare, but the disassembly completed without errors and there were no invalid opcodes. A partial dump of the Cromemco CDOS 1.0 ROM from 0x100 through 0x16F shows the words CROMEMCO RDOS in the binary.
I would post the content of the Cromemco ROM image for posterity if I knew a good place to upload it.
The code in my custom EPROM appears to be only a bootstrap loader. It's in the range of 0x0000 through 0x00A5, so it's very short. I vaguely recall that I had all of CP/M in a disk image that was loaded at the top of RAM. So I think my custom EPROM simply loaded the CP/M image into memory and then jumped to CP/M's start point. I found a paper assembler listing of my modified CP/M for this system. I don't plan to include it in this sale. Please let me know if it's something that would be of interest to you.
Please let me know if you have any questions.
This drive used to boot my CP/M, but It's been in storage for around 4 decades.
The 4FDC board has a modification shown in the pictures. I don't remember why. It most likely has a custom EPROM too. The assembler source for the EPROM might be on the floppies, or maybe on my 8" floppies that I'll be listing soon with the Calcomp drives and a Tarbell controller.
I don't know if these floppies are readable. I couldn't read them with a PC and a CP/M reading utility. I did read the DEC VT-180 (Robin) floppies that were stored in the same box as these IMSAI floppies.
I am listing these parts as a bundle in hopes someone can use the whole set. If you only need the drive or the controller, then message me. I am open to breaking up the bundle if it makes sense.
Please let me know if you have any questions. I'll do my best to answer, but please understand that I haven't touched this computer in about 40 years.
Item might be shipped by USPS, FedEx, or UPS. Quoted shipping cost won't change.On Jul-24-21 at 06:06:03 PDT, seller added the following information:UPDATE!!! I found the original RDOS 1.0 ROM for this board! My memory is still fuzzy but was improved by finding this chip. The Cromemco 4FDC board was shipped with the RDOS ROM which had boot & drivers for the CDOS operating system. I wanted to run CP/M not CDOS, so I wrote my own boot & drivers ROM. That's what's shown installed in the board. The original Cromemco RDOS ROM will be included with this sale. I haven't yet read it because I don't have a 2708 programmer. Might rig something up and will update.
Pictures follow. Note that the pins have some black goo because the ROM has been sitting in anti-static foam that decomposed.
On Jul-24-21 at 06:16:24 PDT, seller added the following information:Note: When I pulled the drive out of the case, one of the header wires was out of the header. I don't remember if this was a mod to deal with drive select or if it just slipped out. I put the wire back in the header. In case you will need this info later, I'm attaching a picture of how it looked when I took the drive out of the enclosure.
On Jul-24-21 at 06:18:55 PDT, seller added the following information:
On Jul-25-21 at 06:45:17 PDT, seller added the following information:UPDATE: I successfully read both my 2708 EPROM and Cromemco's ROM. I created a binary file of both and disassembled them. I can't for certain say all bits are correct because I have no original images to compare, but the disassembly completed without errors and there were no invalid opcodes. A partial dump of the Cromemco CDOS 1.0 ROM from 0x100 through 0x16F shows the words CROMEMCO RDOS in the binary.
I would post the content of the Cromemco ROM image for posterity if I knew a good place to upload it.
The code in my custom EPROM appears to be only a bootstrap loader. It's in the range of 0x0000 through 0x00A5, so it's very short. I vaguely recall that I had all of CP/M in a disk image that was loaded at the top of RAM. So I think my custom EPROM simply loaded the CP/M image into memory and then jumped to CP/M's start point. I found a paper assembler listing of my modified CP/M for this system. I don't plan to include it in this sale. Please let me know if it's something that would be of interest to you.
Please let me know if you have any questions.
