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new_castle_j
July 10th, 2015, 11:52 AM
Can anyone identify this S100 video board? I don't see any brand names marked on it.

25243

griffk
July 10th, 2015, 12:36 PM
Can anyone identify this S100 video board? I don't see any brand names marked on it.

Well, I *thought* it was a Solid State Music ("The Blue Boards") bd at first, but the VDB-1 had a different layout.

You have got to love the technical *exactedness* of the etching "VI DEO BD / REV B" :}
Kinda takes me back to the MA&PA atmosphere of the S100 business in the '70s - Pretty cool actually!

Not too many S100 boards used blue colored material, but a few did, so I'll keep looking...

gwk

JDallas
July 10th, 2015, 04:16 PM
Looks a little *hobbyist* to me.

The layout is missing a lot of normal guideline heuristics, some odd connector choices, the power etches so close to the edge of the board... bad. I'm naturally suspicious with their regulator with no heatsink... perhaps it hit the sweet zone of needing that package's current but not needing heatsinking... normally that's a technical oversight. Even saw that in S-100 boards by Octagon in the early 80s.

I'm curious about the intended function, appears to have a lot of byte-wide static ram though the photo resolution doesn't really allow reading many chip IDs. Seems to have more 40-pin chips than it should need. Maybe its there to do "sprites" or offloading the system for early game rendering?

Maybe it was a home entrepreneur's design development that never really got to market? Maybe it was done by a small contracting firm and they needed a display to meet special client requirements... they could better afford to design a one-off board.

What do you know of the board's history? Where'd you get it? etc..

Can you provide some binary or hex dump of the eproms? That's a good place to find project names and credits.

monahan_z
July 11th, 2015, 07:25 AM
Definitely looks like a hobbyist/home made board.
John

griffk
July 11th, 2015, 10:34 AM
I am not sure..I photoshopped it and enlarged/contrast enh, etc., and came up with an 8237 ir 8257 for the left-hand 40pin chip (either way its a DMA controller), and then the Toshiba is static ram, and I can't make out much more on the big chips...

The traces look pretty clean and professional - no undercut apparent, straight and consistent. It might have been done in a small PCB house, and it had to be from someone who had layout tools (since stuff like OrCad and such was pretty rare in 'the '70s). Had to have been done on a mini/workstation, I think...

Can the OP get a closer/clearer set of pics for the chips--that *might* tell us more.

gwk

griffk
July 11th, 2015, 11:01 AM
the power etches so close to the edge of the board...

That is GND, going around the outside, and I have seen many S100 bds do this, But now I'm wondering about the ribbon cable coming off in the middle--could this have been an early "capture" board, for doing grabs from a video camera, to, say, print dye-sub on coffee cups or t-shirts???

gwk

new_castle_j
July 11th, 2015, 08:40 PM
25257
Thanks for all the replies, I took the eproms off and captured their contents.

I don't know any history on this board, it came with a box of other old computer stuff. Is anyone interested in it? PM me and it's yours, just pay shipping.

daver2
July 12th, 2015, 05:44 AM
I can't see any ASCII text in either EPROM.

The LEFT EPROM contains the executable machine code.

The RIGHT EPROM is a character generator.

The CPU is clearly an 8080/8085/Z80 (or one of the 'clones') as the instruction at location 0x0000 is 'C3' (an absolute jump) to address 0x0100 where there is code to load up the Stack Pointer with 0x9FDF (which must be RAM of course).

The character generator appears to contain the ASCII characters from SPACE (0x20) up to (and including) 0x7E (it may also include 0x7F as a 'block' character). Each character consists of what looks like 8 bits wide by 11 lines high (but not all the bits may be used of course - my guess is that only 7 bits of the width are actively used (with the most significant bit of the byte either remaining unused or blank as an inter-character gap)). The first line (top line) of each character appears to be blank. The bulk of the character occupies the next 7 lines with what looks like a potential descender line and two further blank lines on the 'bottom' of the character.

Dave

JDallas
July 15th, 2015, 05:50 AM
...Had to have been done on a mini/workstation...

I disagree... looks taped to me.