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Anyone recognize this S100-looking thing?

falter

falter

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I feel like it's either and SBC or terminal - I'm leaning towards an SBC because of the S100 slot.
 

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I don't have the measurements yet but doing some scaling to compare to the Sol board it does seem to be smaller.
 
The important measurement is the distance between the S-100 slot and the back, IE, is there enough room to slot in a backplane to hold more cards without them grossly overhanging the I/O on the board. That would be a good sanity check whether the slot might be proprietary.

Anyway. It might not literally be meant for a SOL-20 case, but it clearly reads like a knockoff heavily inspired by it. I see a “speaker” header connection on the board, does it look like it has video generation on it? Your pictures are too low res/blurry to read most of the small chip markings, and therefore I can’t really convince myself one way or the other. There’s only the one wide footprint ROM, which is probably CPU code, but it’s at least possible there’s a skinnier character generator hidden somewhere. Also don’t see anything that obviously looks like video SRAM, but again, if it’s older small packages I might not be able to read it.

Anyway. It does have 64K on board, which seems like a lot for something intended for a dedicated terminal.

Is this a random eBay find with no provenance?
 
… Anyway, at this point my crystal ball is suggesting this *might* be some very early Tawainese/Hong Kong-originated computer? It gives vibes like the Apple clones that got churned out in droves, maybe they made a SOL-20 “ripoff” in the early days?
 
Eudimorphodon said:
The important measurement is the distance between the S-100 slot and the back, IE, is there enough room to slot in a backplane to hold more cards without them grossly overhanging the I/O on the board. That would be a good sanity check whether the slot might be proprietary.

Anyway. It might not literally be meant for a SOL-20 case, but it clearly reads like a knockoff heavily inspired by it. I see a “speaker” header connection on the board, does it look like it has video generation on it? Your pictures are too low res/blurry to read most of the small chip markings, and therefore I can’t really convince myself one way or the other. There’s only the one wide footprint ROM, which is probably CPU code, but it’s at least possible there’s a skinnier character generator hidden somewhere. Also don’t see anything that obviously looks like video SRAM, but again, if it’s older small packages I might not be able to read it.

Anyway. It does have 64K on board, which seems like a lot for something intended for a dedicated terminal.

Is this a random eBay find with no provenance?
Click to expand...
Yes.. and hand to heart, I was not looking for this. I was on ebay trying to find a no longer sold Lexmark printer for a client who has a stack of carts they need to burn through. And this just randomly popped up. And it only caught my eye because I know the Sol PCB really well and it definitely resembles one. I feel like this may have been ripped out of something and may have been a more complete package than this, but who knows.

This is the original auction if it helps for zoom in purposes. Not sure why but when you save images from ebay they lose quality. I'm thinking it's a computer because I don't really see anything to do with video onboard, so to me it looks like a serial based SBC that talks to a terminal. I can't really make out any of the usual chips (like MC1488/89) that I personally recognize for that sort of thing though.

I'm hoping it's just a random late 70s SBC, maybe among dozens and dozens that were being offered back then in magazines, etc. Sure does have an uncanny resemblance to the SOL though, as you said.
 
The hand-scrawled label on the eprom being dated “/85” is… interesting.

Anyway, I did spot an MC1489 on it, but if you don’t even have it in hand yet I don’t think there’s a lot of snooping to be done here. The pictures don’t really cover the two rows of logic between the slot and the RAM so it’s difficult to say if there’s enough there to make a video signal. The shape of it overall suggests something you’d build into a SOL/Apple shaped case with a keyboard over the ram chip area, but it’s possible the intention was to have some disk drives in front of a vertical backplane.

The thing this *doesn’t* feel like to me is something that was sold bare; unlike something like a BigBoard it seems like it was intended for a very specific case. Even if it doesn’t have video on the motherboard it might have had a video card slotted if being used in a console. (The SOL needed a RAM card to be useful as a computer; the fact that this has gobs of RAM onboard would make it suitable for both console and headless configurations.)
 
Many years ago, a company I used to consult for, developed an embedded Z80 computer system that require a colour graphics display terminal. The simplest (and cheapest) solution in the end was to add an IBM PC slot to the board and purchase a graphics card. The embedded Z80 firmware then just drove the CGA, or EGA or VGA display card (whatever was cheaply available at the time) using an appropriate update to the firmware. These systems (because they were embedded) had a large amount of EPROM - and not so much RAM of course.

Dave
 
jlang said:
I don't see enough logic to produce video. So I'm going to call it a Z80 SBC with a S-100 slot.
Click to expand...

I’m not *entirely* convinced but I am probably around 90-10 in the no video camp. The board uses a dedicated Motorola chip to drive the DRAM and the compute section and onboard peripherals are all Zilog tinkertoys that wouldn’t need a lot of support chips to decode, so the budget for a really simplistic TRS-80/PET type display might just fit in the number of chips available… but realistically I suspect most of those two rows are there to adapt the Z-80 bus into S-100.

Given the vintage of this board and the fact it holds 64k I would guess if it did have video they probably would have used a CRTC instead of loose logic, and there definitely isn’t one of those. I do wonder what the two empty sockets next to the CTC are for, though.
 
… I still would argue it’s *shaped* like it was designed to fit in a console or terminal style case, in which case video would be in the slot, but… yeah, with no provenance at all it’s going to be rough tracking this down. This was the era where mom and shop manufacturers popped in and out of existence all the time.
 
I am going to guess that some of the PIO lines from U19 are interfaced to the 37-way D connector via the missing U9 and U10 device. I suspect U8 is also part of this interfacing.

U4 appears to be a MC1489 - so what is U3 I wonder?

Who knows what is supposed to go into U17 and U18. More CTCs? The simplest thing would be to see what pins are common from the CTC in U16 with the IC sockets U17 and U18. The should narrow it down to more CTCs or something else.

The EPROM socket looks to be a 'bodge'. It is a 28 pin socket in a 24 pin footprint! So this is either a 'repair' or a 'repurpose'.

I would also trace the serial transmit and receive lines from the Z80 DART to see where they go.

I am just wondering whether U2 is an optometrist isolator? The presence of a high-wattage 470 Ohm resistor could indicate the presence of a 20 mA current loop interface - possibly combined with RS232?

Now, dumping the EPROM may give us some insights...

Dave
 
I should be receiving the board in a couple of weeks. Really looking forward to dumping that EPROM and exploring what this is!
 
I will also be interested in further exploration....
I looked at the pictures, I can't find anything that looks like a clock source!
Did I miss it???
 
daver2 said:
The EPROM socket looks to be a 'bodge'. It is a 28 pin socket in a 24 pin footprint! So this is either a 'repair' or a 'repurpose'.
Click to expand...
It's pretty standard forward-looking design to put in a 28-pin socket that's compatible with 24-pin devices if you currently need e.g. only a 2KB (2716) or 4KB (2732) EPROM but might want to expand to 8KB (2764) later.

I would also not assume that that slot is S-100 just because it's got a hundred pins. Plenty of machines used that 100-pin slot with other pinouts. Beep it out before trying to plug in an S-100 board!
 
Good point about the 100-pin connector.

If you look at the 28-pin socket, 4 of the pins are splayed horizontally onto the PCB!

Dave
 
daver2 said:
If you look at the 28-pin socket, 4 of the pins are splayed horizontally onto the PCB!
Click to expand...
Lol, I'd not noticed that. In that case I'm going to go with, "they ran out of 24-pin sockets."

Though it is still usable for a 2764 if you bodge wire pin 28 to Vcc and pin 2 to whatever you want toggling A12. (Could be an address line, could be just a manual switch to make it easy to switch between two ROM images.)
 
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