falter
Veteran Member
Not sure if this a 'prototype' as the seller described or just a one off.. kinda looks like your run of the mill Z80 project. Hope the EPROM contents are intact.
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Z80 Something or Other I bought for $25
- Thread starter falter
- Start date
falter
Veteran Member
NeXT
Veteran Member
That's a really well equipped system. Z80, PIO, SIO, DMA controller, RTC, MMU, 512k DRAM (with parity?)
durgadas311
Veteran Member
Quite a mystery, as a hobbyist probably couldn't/wouldn't fabricate a PCB like that. Also a mystery as to why it seems to be complete with lots of traces, but then there's all the wirewrap on the back side. I wonder if the PCB is some sort of template/first-pass at the final product, and then they wirewrap the less-obvious details in order to figure out the final PCB. That's an awful lot of wirewrap "fixes".
Is there evidence that a lot of (any) traces were cut? I'm wondering if this was a PCB meant for something else and then it was butchered for this purpose, or just a partially-finished PCB that needed more connections. The layout seems to imply the PCB was intended for these same parts where they are.
Is there evidence that a lot of (any) traces were cut? I'm wondering if this was a PCB meant for something else and then it was butchered for this purpose, or just a partially-finished PCB that needed more connections. The layout seems to imply the PCB was intended for these same parts where they are.
syzygy
Experienced Member
Nice!
Curious about the faint lettering....just the board material manufacturer?
Curious about the faint lettering....just the board material manufacturer?
falter
Veteran Member
Not sure - waiting for it to arrive and then will do a deep dive. It kind of looks like it has maybe DB25s and DB9 on one side? Not sure what the bigger connector on the other side is for. I wish ebay allowed for higher res photos.. like syzygy I bet some useful information is contained in the lettering affixed to the board.
daver2
10k Member
Not another machine...
At one stage the EPROM did have a label on it. I wonder if the seller still has the label?
Dave
At one stage the EPROM did have a label on it. I wonder if the seller still has the label?
Dave
falter
Veteran Member
Well, this one was quite inexpensive and looked interesting. These SBCs don't take up much space, I enjoy these mystery machines particularly. Plus my Youtube audience loves checking them out, even if we don't always get any success. I'll ask the seller about the label but I doubt he still has it. Hopefully it's in better shape than the last Z80 SBC.
daver2
10k Member
>>> I enjoy these mystery machines particularly.
I enjoy your mystery machines also...
>>> Hopefully it's in better shape than the last Z80 SBC.
Yes, hopefully!
Dave
I enjoy your mystery machines also...
>>> Hopefully it's in better shape than the last Z80 SBC.
Yes, hopefully!
Dave
exidyboy
Experienced Member
You might want to put a link to your channel in your profile ...
Kelly Gray
Member
That looks like a very interesting board. 512K of DRAM, PIO, DMA, RTC, and what appears to be 4 RS-232 serial ports. (2xSIO/2 and a bunch of 1488/1489 chips) There also appears to be provision for a daughtercard of some sort.
At a guess, I'd say the small two pin connector at the bottom right is for power, as there is a switching regulator circuit right next to it. The next one up is probably serial, then either parallel or multiple serial ports on one connector. The top connector on the right might be to control some sort of external device. There's the fuse, what looks like a power switching transistor, and a bunch of analog circuitry. Possibly a tape drive interface?
The big connector on the left is quite likely some sort of bus expansion/test port.
At a guess, I'd say the small two pin connector at the bottom right is for power, as there is a switching regulator circuit right next to it. The next one up is probably serial, then either parallel or multiple serial ports on one connector. The top connector on the right might be to control some sort of external device. There's the fuse, what looks like a power switching transistor, and a bunch of analog circuitry. Possibly a tape drive interface?
The big connector on the left is quite likely some sort of bus expansion/test port.
falter
Veteran Member
Yeah I probably should.. I just don't like promoting on this forum - feels wrong. I prefer to just be a genuine enthusiast here.
daver2
10k Member
>>> I just don't like promoting on this forum - feels wrong. I prefer to just be a genuine enthusiast here.
You are too modest. You have been here long enough to have 'proved your credentials' as a genuine enthusiast at least! Link to your channel... I am sure the rest of the enthusiasts (me included) would value it.
Dave
You are too modest. You have been here long enough to have 'proved your credentials' as a genuine enthusiast at least! Link to your channel... I am sure the rest of the enthusiasts (me included) would value it.
Dave
Bob-O-Rama
Experienced Member
That has a little bit of everything! Hopefully the ROM will give you some clues. The somewhat baffling thing is that the wire wrap seems entirely additive. I don't see any cut traces indicating rework. It almost like the board is 2 layers of a multi layer board, and the bodge is the other layers. If somebody found a working Z80 board and then decided to rework it, I would expect a lot more cut traces and so on. Looks designed to be inserted into a case or chassis. Can't wait to see what you find.
falter
Veteran Member
Okay so I finally got the board itself. It is a prototype! Of what I don't know.. but the lettering says WTD Inc. 1985 etc on each side. The most I could find is that WTD was some sort of terminal manufacturer and was acquired in or around 1986. Anyway here's the pics. I have also dumped the ROM, and it appears to be good.. so maybe that offers some clues.
Attachments
falter
Veteran Member
falter
Veteran Member
ROM dump.
bzotto
Experienced Member
falter
Veteran Member
Yeah that Computerworld article was all I could find. Seems to suggest this is a terminal maybe. I'm wondering if 512kb RAM would have been in the realm of normal for a terminal in 1985. Seems like a lot.