• Please review our updated Terms and Rules here

STD BUS Win Systems MCM-SBC Docs Needed

A

Amardeep-AC9MF

Experienced Member
Joined
Jul 22, 2017
Messages
115
Location
Central Indiana
I have a 4MHz Z80 single board computer with an 8" floppy drive interface that looks interesting. But I haven't been able to find any documentation on it. It is circa 1983 and the company is still around but seems to have abandoned all its legacy documentation. Anyone have leads or documentation? Thanks!

Win Systems Model MCM-SBC
1983
 

Attachments

  • IMG_20231127_152421695.jpg
    IMG_20231127_152421695.jpg
    707.1 KB · Views: 22
It's an interesting board. I have never seen those specific programmable logic ICs before. They look like a subset of GALs or maybe something newer. I would have guessed it was a board from the late 80s or early 90s except for the 2716 ROM which is a bit small, but the socket is larger so who knows.

It clearly has a serial input/output line, and a FDC with non-standard ports, but it should be possible to figure out which pin goes where... Finding boot disks though? No idea, or the disk geometry though you could go as far as reverse engineering some of that from signals to the FDC.

Those red stickers look pretty ominous. I never like to see small red stickers on specific ICs. Makes me wonder if someone was repairing it.

Have you plugged it into a RS232 port to see what characters it sends to the serial port on boot? There's not enough ROM to do much there and it's probably just a BIOS bootstrap. But it's only 2K so should be easy enough to disassemble.

Even if you can't locate the original software, it should be possible to figure out how to make it boot depending on what you want to do. It's pretty quick to figure out if it's going to establish a CP/M style OS. Look for the jump tables being installed in upper memory early on in the code execution...

Which reminds me, I need to build a z80 disassembler to run under Windows some time... Are there any good disassemblers for such tasks? Should be easy to read the ROM and figure out what it does.

David.
 
cj7hawk said:
It's an interesting board. I have never seen those specific programmable logic ICs before. They look like a subset of GALs or maybe something newer. I would have guessed it was a board from the late 80s or early 90s except for the 2716 ROM which is a bit small, but the socket is larger so who knows.

It clearly has a serial input/output line, and a FDC with non-standard ports, but it should be possible to figure out which pin goes where... Finding boot disks though? No idea, or the disk geometry though you could go as far as reverse engineering some of that from signals to the FDC.

Those red stickers look pretty ominous. I never like to see small red stickers on specific ICs. Makes me wonder if someone was repairing it.

Have you plugged it into a RS232 port to see what characters it sends to the serial port on boot? There's not enough ROM to do much there and it's probably just a BIOS bootstrap. But it's only 2K so should be easy enough to disassemble.

Even if you can't locate the original software, it should be possible to figure out how to make it boot depending on what you want to do. It's pretty quick to figure out if it's going to establish a CP/M style OS. Look for the jump tables being installed in upper memory early on in the code execution...

Which reminds me, I need to build a z80 disassembler to run under Windows some time... Are there any good disassemblers for such tasks? Should be easy to read the ROM and figure out what it does.

David.
Click to expand...

Just curious what you mean by FDC with non-standard ports?

I was considering doing the disassembly approach to figuring out a way to learn it's port mappings. That might very well be the only way to crack its secrets if the manufacturer can't come up with anything (I've put in a request with them for technical docs).

The red stickers were indeed from a repair. I found it when scavenging through a soon-to-be closed storage unit for a company that used to use them in test equipment. It has paperwork from the factory where it was sent in for service and returned in repaired and working condition. Then it sat unused as a spare that was never needed.

I no longer have any STD bus chassis so I'll have to rig up a way to power it so I can observe any activity on the serial ports. Thanks for the suggestions.

Here is a page listing a number of disassemblers by platform: http://www.z80.info/z80sdt.htm#SDT_DISASM

Regards,
Amardeep
 
It looks to be a 50 pin connector rather than the usual 34 pin for a FDD. So unless you have some 50 pin FDDs around, you might need an adapter - eg https://www.tindie.com/products/siliconinsider/8-floppy-disk-interface-50-pin-to-34-pin-adapter/

You will likely need 12v plus and minus and 5v. You can figure out that from the serial drivers and any 5v point back to an edge connector.

The link you gave had the same problem I mentioned though I wasn't specific enough, Modern windows, ie Windows 10 compatible. There are few z80 tools for Windows 10 which is why I wrote my own z80 cross assembler. And will need to write a disassembler too some time. :)
 
Oh, ok. 50 pin is the 8" floppy standard so I was puzzled by what you meant by non-standard. If I get it fired up I'll use 8" drives with it. Win Systems got back to me that they don't have any documentation for products that old, so I guess reverse engineering is the way it's going to go.

What keeps any of those tools from running on Windows 10/11? Do you mean you're looking for Windows based GUI apps?
 
No, just text-based, but stuff that runs under Windows 10/11 CLI... Which a lot of older stuff does not :(

Some windows 8 stuff does, but most of the z80 stuff came out much earlier... And hung around until Windows 7.

Usually it just doesn't work. Some GUI stuff does, but a lot of the older CLI stuff just errors out. :( Have you tried anything that works under 10/11?
 
cj7hawk said:
No, just text-based, but stuff that runs under Windows 10/11 CLI... Which a lot of older stuff does not :(

Some windows 8 stuff does, but most of the z80 stuff came out much earlier... And hung around until Windows 7.

Usually it just doesn't work. Some GUI stuff does, but a lot of the older CLI stuff just errors out. :( Have you tried anything that works under 10/11?
Click to expand...
I think I bailed on Windows before hitting that problem. I might suggest using WSL as the tool selection is much better.

Well, if I make any progress with the SBC I'll post updates here. Thanks for the suggestions.
 
I used to blame Microsoft for failing to support that, but then as it was noted during a recent discussion here tht Microsoft did an amazing job keeping things backwards compatible all the way back to the XT world for a very long time.

I do us WSL now, but it's a pain... And the experience is inconsistent. But I'm forced to use it with some software I use often - eg, GALASM.

Sometimes it's easier to just write it myself. Time consuming yes, but then I get the program I like... I should probably clean up my assembler some time for others to use. And write up more tools for people to do stuff like convert from multiple 8080/8085/z80 formats to it's own format... But I got a bit lazy and began doing stuff like acceping .ORG and ORG as both valid and changing a lot of stuff. Some of it is good -eg, I can use quotes interchangebly - so "'" and '"' are both valid to give the bytes for ' and " - The rule is that quotes have to be consistent - the string must end with the same quote it starts with.

Also, I used to support strings but I need to simplify that to simplify the maths I'm using so I can allow formulas on lines... But at least I'll have the same z80 assembler on Windows 11 that I have on my CP/M system.

Anyway - Looking forward to what you find ! :)
 
Early this summer I got a version of this board up and running CP/M off of 8" disks. My board may predate yours in that it is marked WINTECH SYSTEMS which later became WIN SYSTEMS. The part numbers appear to be the same though. The EPROM label was missing but it holds a simple monitor; probably that same as yours. As I remember the monitor does not print a sign-on banner or provide a help command.

WINTECH-MCM-SBC.jpg

It will be a couple of days before I can gather up and make presentable the details I gathered; disassembly of EPROM and PLAs etc

Here are the monitor commands as I found. (1200,N,8,1)

; "A" - Arithmetic ?
;
; A <x> <y>
;
; Prints x+y x-y
;
; ex. a 2000 F
; prints
; 200F 1FF1


; "B" - Boot from floppy
;
; Read sector 1 from track 0 to 0x0080 then jump to 0x0080.
; A single density sector loads 128 bytes and a double density
; sector loads 512 bytes.


; "C" - Copy memory
;
; C <start> <end> <dest>


; "D" - Dump memory
;
; d <start addr> <end addr>
; d <start>
; d


; "F" - Fill memory
;
; F <start> <end> <data>


; "G" - Go
;
; Transfer control to specified address
;
; G <addr>


; "H" - Load hex records


; "I" - Read I/O port
;
; I <port>
; CR reads next port
; - reads previous port


; "M" - Memory examine/modify


; "O" - Write I/O port
;
; O <port> <value>


; "T" - Test memory
;
; T <start addr> <end addr>
 
jxm said:
Early this summer I got a version of this board up and running CP/M off of 8" disks. My board may predate yours in that it is marked WINTECH SYSTEMS which later became WIN SYSTEMS. The part numbers appear to be the same though. The EPROM label was missing but it holds a simple monitor; probably that same as yours. As I remember the monitor does not print a sign-on banner or provide a help command.

View attachment 1268837

It will be a couple of days before I can gather up and make presentable the details I gathered; disassembly of EPROM and PLAs etc

Here are the monitor commands as I found. (1200,N,8,1)

; "A" - Arithmetic ?
;
; A <x> <y>
;
; Prints x+y x-y
;
; ex. a 2000 F
; prints
; 200F 1FF1


; "B" - Boot from floppy
;
; Read sector 1 from track 0 to 0x0080 then jump to 0x0080.
; A single density sector loads 128 bytes and a double density
; sector loads 512 bytes.


; "C" - Copy memory
;
; C <start> <end> <dest>


; "D" - Dump memory
;
; d <start addr> <end addr>
; d <start>
; d


; "F" - Fill memory
;
; F <start> <end> <data>


; "G" - Go
;
; Transfer control to specified address
;
; G <addr>


; "H" - Load hex records


; "I" - Read I/O port
;
; I <port>
; CR reads next port
; - reads previous port


; "M" - Memory examine/modify


; "O" - Write I/O port
;
; O <port> <value>


; "T" - Test memory
;
; T <start addr> <end addr>
Click to expand...

Wow! Thank you so much for sharing. I was hoping on the off chance someone had ran into one of these but it sounds like you really made some progress with it! Did you have to write the CP/M CBIOS for it after deciphering the I/O from the boot ROM?
 
cj7hawk said:
It's an interesting board. I have never seen those specific programmable logic ICs before. They look like a subset of GALs or maybe something newer. I would have guessed it was a board from the late 80s or early 90s except for the 2716 ROM which is a bit small, but the socket is larger so who knows.
Click to expand...

Are you referring to the N82S153N devices? I assume those are compatible with the Signetics PLS153 devices. Details about those devices can be found in this databook:

http://www.bitsavers.org/components/signetics/_dataBooks/1987_Signetics_pldData.pdf

I have some boards that use the same family PLS173 devices, which were replaced by 20V8 devices in newer revs of the board.
 
You must log in or register to reply here.
Back
Top