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Anyone know what this board is for?

P

Primo007

Member
Joined
Apr 15, 2022
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19
Location
Portland OR
I recently got this board on eBay as a "Heathkit Zenith Terminal Board 204-1697-03." When I looked up the numbers it didn't come up with anything, no surprise there, but it doesn't have any other markings on the board that I could look up. It seems that these were used in CP/M machines with a configuration similar to the apple 1, where there would be a terminal and computer as part of the same system. This one has a few oddities, as it seems to have an AT style keyboard connector (it fits my AT keyboard but its unknown if the pinout is the same) and some connectors that look like they might fit an AT power supply (though again, probably not pin compatible). It also had a few chips, the Intel p8276, that when I looked them up I found that they were video controllers, which seems strange for what's supposedly a terminal board. They could be character generators, but then why would there be 2? Extra characters maybe? But that seems unlikely. If anyone has any information on what this board it it would be much appreciated!

I can take more pictures if anyone needs!
 

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It's certainly not an H89/Z89 terminal board (H19/Z19). The 8088-based Z100 did not have a terminal board, AFAIK. The date codes on the chips don't align with any of those machines. Can you identify a CPU chip? This looks like something else entirely. Are there any manufacturer markings? maybe on the back of the PCB?
 
I'll have to take off the back grounding board to see if there's any markings on the back of the main PCB, but I'll most likely be able to do it a bit later today or tomorrow since it has to come off anyway as some of the solder holding on broke in shipping.
As for the CPU chip, I'm assuming its the one underneath the heat spreader? It had pretty much no markings aside from Malaysia and a few identifying numbers/letter that came up with nothing when I looked them up.
 
Also I just noticed some chips with "Datapoint 1003-050" on them, so I guess the seller just mislabeled it as a zenith.
 
Dump the roms and check for text. Date codes are 1990, so way late for a CPM, and it's got 24K of SRAM on it. (3 TC5565APL Chips @ 8k each)
 
Zenith had some late terminals. The Z-39 was similar to the Eazy-PC but the connectors according to the one manual I could find are laid out differently. There was also a Z-49 which had a small box under the display but the brochure shows nothing of the interior boards.

Two character generators might make sense for the Z-49 which was designed for a 80 column mode using 10x12 characters and a 132 column mode using 8x12 characters.
 
I just wonder if its some kind of terminal for APL. Some of the chips say "APL" on them, and you may need two character generators, one for the "normal" character set and one for the APL character set.
 
We don't have a clear (hi-res) picture of the whole PCB, nor a view of the back of the PCB, but I can identify an Intel 8276 CRT controller chip as well as what appears to be an Intel 8271 Floppy controller chip. There's a PLCC chip that doesn't seem to have adequate markings to identify, plus another DIP-40 hidden beneath the ground strap. This doesn't look like a terminal at all. I do only see 24K of RAM (three 8Kx8 static RAMs scattered around), so not likely to be a general-purpose computer. Perhaps some sort of embedded/manufacturing-control computer. There may be some custom-LSI (the PLCC chip?) which may be difficult to identify.
 
durgadas311 said:
We don't have a clear (hi-res) picture of the whole PCB, nor a view of the back of the PCB.
Click to expand...
Yeah sorry about that, that's just what my camera can do for right now, as for the back of the PCB they're is a large grounding plate back there that covers the entire main PCB that I'm currently writing on trying to remove
 
Yes, you need to get your posts up to 10.

It would also be helpful to add your location to your profile.

Dave
 
Got a few more pictures after taking off the grounding plate. As usual if you need more feel free to ask!
 

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The pieces are starting to fall into place, perhaps. So, the board's CPU is an AMD copy of Intel-licensed 80186. That other DIP-40 might be some sort of UART perhaps. My guess is that "DKL" is the manufacturer of the ground plane, so probably not terribly relevant.

On the back of the PCB I see "ML-IV-0 3690 / 94V-O" - assuming this is Datapoint product (as the PAL label implies) - that may refer to the Datapoint 3600 system (was there such a thing?). I've not been able to find any information on later Datapoint products, so can't tell what they were doing in 1990. Some of the 1980's products talk about "5500 Emulation", which I believe refers to the original "CPU" language, so that may be what they did in order to use modern off-the-shelf CPUs like 80186 and maintain backward compatibility.

Maybe it will help to get clear identification of all the "large" ICs. That's all the DIP-40s plus the DIP-28s. But without a hardware reference manual for later Datapoint products, it will be difficult to determine. This one seems to have a very small amount of memory, compared to the product descriptions from the 1980s, so perhaps it is not one of their normal terminals. It also appears that Datapoint did not assign model numbers in chronological order, based on what information is available on bitsavers.
 
I suppose a more logical guess as to the model, if it is Datapoint, would come from the EPROM labels. "FW7350 2.4" might suggest it is firmware v2.4 for the Datapoint 7350. But, I'm not finding anything on that model/family. The "1220-015A" on the PAL, along with "1166-005F" and "1166-006F" on the EPROMs, are probably just internal part numbers (and not directly indicative of the model). The "3690" on the PCB might just be a (PCB manufacturer) date code, albeit WWYY instead of the YYWW normally used on ICs.
 
That would make scene, since I found the real datapoint 3600, which was WAY older than this. I'll try to find something, but I doubt I'll be able to find any more than what you have. Either way it is nice to have a bit more information on this even if we don't have a name yet.
 
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