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Single Board Computers

Old Computers

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I just acquired two SBC's. One of them is called The Bigger Board SBC-2001 Z80A manufactured by Business Information Systems. I have the manual with it, and it implies that a CP/M customized for it came with it. Can I modify CP/M myself?

I also have another SBC that does not have a name from what I can tell, but it is manufactured by Molecular Computers, and the numbers on it are 1000082 REV A FPX 80. 90272002 REV HI. Doing a search for it turns up nothing relevant. Do any of you know anything about this computer?

Thanks,
Old Computers
 
1) Definitely--DRI even published a "System Alteration Guide" for folks wanting to write their own BIOS. Check Gaby's CP/M site for copies of it.

2) If it's the same Molecular, that I'm thinking of, it might not be quite stand-alone. Molecular specialized in multi-user systems, so an SBC would seem not to belong to their portfolio. But there was more than one Molecular, so it's hard to say without seeing the board.
 
Thank you very much Chuck(G).

I can post some pictures of the second computer if you would like to see what it is. I did inspect the board, and it appears to be stand-alone. It has two rows of pins that appear to be serial ports, two PSU inputs, and two disk outputs. There is a Z80A on it, and a Z80ADART, Z80CTC. It also has a huge bank of what I am guessing are RAM chips, and an EEPROM with the sticker reading 50250130 G.
 
Well, @OC, here's the logo of the company that I recall:

73379822.jpg


They had the approach of using one Z80 as a supervisor with each user having his own Z80. Circa 1979-82 or so. You could have, IIRC, up to 16 Z80 user cards in a box.
 
I could not find the logo on the board anywhere. If it might help with identification, the board appears to be factory assembled. I'll go ahed and post a couple of photos tomorrow.

So if it turns out to be the type of system you described is it pretty much useless unless I find the other componets? That sort of system sounds very interesting.
 
The logo looks familiar, does anyone have any back issues of BYTE ? I wanna say there was a lengthy review in one, but mine are boxed up at the moment.
Old Computers, is there a FCC number on the board, by any chance ?
patscc
 
I checked the board, and there does not appear to be any FCC ID. I did look at the numbers on the board a bit closer and I think that it is the Molecular Computers you guys are talking about. The designation FPX BD makes me think that it is some kind of sub board to a system. What do you think?
 
The name of the company that I'm thinking of is "Molecular Computer, Inc" (note singular "Computer"). If your board is labeled with "Computers" (plural) instead, I have no idea of what you've got.
 
I guess that that board will remain a mystery for now. I searched for it, but all the results are things about DNA and computers. (Pictures will come soon. I have just been very busy lately)

I was able to test out the SBC-2001, and it appears to work perfectly. I ran its memory test for about 5-10 minutes and it did not return any errors. I also had it display its rom contents and it returned the bytes. One thing I noticed about it though is that the manual said that the ROM address was from C000 to CFFF. Around CE00 It started to return 00 for the bytes. Is that just because the monitor does not fill the EPROM?

The bad news is that its CP/M BIOS is not built in to the ROM. The manual mentions a BIOS disk and a distribution disk. I am guessing that CP/M will be easy to modify, but I am unsure about the BIOS. I have never written anything in assembly or machine code before. I am guessing that sample BIOS's that are in my CP/M programmer's book will not work since BIOS is system specific.
 
I have done a basic search, nothing too major. I did look on Gaby's CP/M site and Dave's Old Computers website, but I did not find my system listed. I could probably search some more in those sites though. I tried to see if Business Information Systems still exists, but searching did not turn up anything. It was located in Johnson City, Tennessee.
 
There's still a Business Information Systems listed in Tennessee. If you haven't, you might want to try giving them a call on the off-chance it's the same outfit.
patscc
p.s. if they are, and they offer you a bunch of old boards and docs they have no need for, I'd like some. :)
 
While not unknown, CP/M BIOS in ROM was not common. Most systems coded it as part of the boot record, just as you see it in the "System Alteration Guide" . If you can puzzle out what's what port-wise on your SBC, you can write your own very easily.

There was a lot of copying from reference designs back then, so you may also want to see if there's an Ampro or Yasbec design that matches.
 
@patscc: I looked them up, and the city they are located in is very close to the Johnson City TN, so it probably is the same company. I will look into contacting them.

@Chuck(G): I will look into those ideas.

Do you recommend any Z80 assembly/machine code tutorials?
 
Do you recommend any Z80 assembly/machine code tutorials?

As strange as it sounds, I'd recommend learning 8080/8085 code first. The big reason is that the DRI coding guides all use 8080 examples, not Z80. The stock CP/M assemblers (ASM and MAC) are 8080.

As far as tutorials, no recommendations--I learned from the datasheets when the chips came out.
 
Will a datasheet be easily found from an internet search?

As I start this project I will probably ask for some more help.
 
Here are some pictures of the Molecular Computers board.
IMG_0933.jpgIMG_0935.jpg

Some more news about the SBC-2001: I have been running the test for the D command which outputs the contents of the memory to the console. It seems that if I enter parameters greater than 0 the computer freezes up. Could the EPROM have lost some of its data? I do have the monitor listing if I need to re-assemble it.
 
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