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Odd duck 386

It's possible... but I'd have to configure the memory with jumpers, and without a reference it looks like quite a project.

Here's a high-res picture of the board (2MB file)

http://img4.imageshack.us/img4/1143/img5577p.jpg

There's the other/64k jumper (now in the "other" position), then there's the block of 9 jumpers without any markings... unless the "64k/256k DRAM" inscription is related to them, as (possibly) the "1M DRAM" notation below them as well...
Then there are the 4 switches in the block of 8 at the bottom, labeled "DRAM"
 
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It looks possible... but I'd have to configure the memory with jumpers, and without a reference it looks like quite a project.

Here's a high-res picture of the board (2MB file)

http://img4.imageshack.us/img4/1143/img5577p.jpg
Looks like the last 4 positions of the DIP switch at bottom center of that pic control RAM, but that's a lot of combinations to try just guessing. Hopefully you can find some documentation on this one.

EDIT: I see a set of jumpers above the 2nd column of ram (from the left) I would bet all up like they are now is for 64/256k DRAM and all down would be for 1m DRAM chips (guessing by the silk screening near it).
 
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For what its worth, if you can get 1m DRAM chips working I would buy all those 256k DRAM chips off you, they should work perfectly to populate my spare AST Advantage! card :D (if not Jameco sells them still, just waiting till I have more stuff to order from them)
 
Yeah, if only I could source them in a place with reasonable costs... to populate this board from Jameco would cost over $60, And ebay is worse even for 511000 chips.

they should work perfectly to populate my spare AST Advantage! card :D

Like this one? :) http://www.ebay.com/itm/Advantage-A...857?pt=LH_DefaultDomain_0&hash=item2563dc3521


<rant> I wish all older hardware came at least with documentation as nice as this: http://www.textfiles.com/bitsavers/pdf/excelan/4200020-00B_EXOS205_Feb86.pdf - I used to have a stack of these monsters, but I gave them all away a few years ago.</rant>
 
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Yes that's the exact card I have I got 2 populated with 64k DRAM chips for a total of 128 kilobytes each, but I combined the DRAM chips from both cards onto one single card for 256kilobytes, and my now empty card (pictured in my link) card. I looked and it would almost be cheaper for me to buy enough 256k DRAM chips to fully populate both my cards at 1.5mb each, since the quantity discount kicks in bigger after 100pieces, its like $40 for 1 card worth or like $60 for 2 cards worth.
 
I was able to find and buy 511000 chips cheaper than Jameco - after S&H they came at just under $1/piece. The catch? There are only 35 of them. Grrr... :)
 
I have some dram left cannibalizing an ast advantage years ago for some other project which escapes me. Nonetheless, let me dig tonight and see what I have... I know I should have at least 20-30 pcs left if someone here needs any. I also have other dram chips as well from motherboards of yesteryear. All worked when I pulled them...
 
Just dug out some of my collection of loose dram chips, so far I've found -

OKI - M3764-20RS - QTY 43 (DRAM 64K X 1BIT) <-- found on AST rampage and other ems cards, and early IBM and compatible motherboards
Motorola - MCM665BP20 - QTY 9 (DRAM 64K X 1BIT) <-- same as above
OKI - m51c256-80 - QTY 8 (DRAM 256k X 1BIT) <-- usually used for base 1mb on ZIP dram based systems
Fujitsu - MB81C4256-80 - QTY 16 (DRAM 1MB) datasheet here <--- believe this is a 511000 compatible but could be wrong, I think 511000s are 1mbit x 1 and these are 256x4, but if I recall correctly, they work just the same. These I believe are cmos based, and not fast page, hence why 256x4 instead of 1mx1.


BTW, keep this vendor bookmarked. http://www.arcadecomponents.com/memory.html
Great vendor for small orders of hard to find dram/74xxx/75xxx etc. I order from him at least 2-3x a year. :thumbsup:
If I don't have it, he usually does! :)
 
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Fujitsu - MB81C4256-80 - QTY 16 (DRAM 1MB) datasheet here <--- believe this is a 511000 compatible but could be wrong, I think 511000s are 1mbit x 1 and these are 256x4, but if I recall correctly, they work just the same. These I believe are cmos based, and not fast page, hence why 256x4 instead of 1mx1.

Unfortunately they're not compatible... the 81c456 have a 4-bit data bus, and the 511000 have a 1-bit bus.


I'm very familiar with that website... 511000s are priced as jameco. I may end up ordering from there the chip needed to complete the banks. And a few spares.
 
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Well I finally got around to testing this motherboard. The news aren't great. I hooked up PS (known good), VGA card and keyboard, turned power on... Keyboard LEDs flash once, then nothing. No video signal, no response to keyboard. Thinking maybe it's one of those motherboards that don't post without a CMOS battery I plugged a battery in (3xAAA). Still no go. I did try another PS too, and 2 other VGA cards, no difference. At this point I'm not sure what else to do. I don't think the motherboard is completely dead, the flashing keyboard lights say otherwise. And after a while one of the chips (you would call it "northbridge" these days) gets fairly warm. But that's about it.
 
it seems that "standard practice" is to pull and reseat all the removable chips. I assume you have a speaker plugged in?
 
it seems that "standard practice" is to pull and reseat all the removable chips. I assume you have a speaker plugged in?

Well good luck to me then... there must be at least 50 of them on the board.
No speaker, AFAIK I need a high impedance one and I don't have one of those. A low-Z speaker might fry the driver stage. I'll see if I can rig something with an audio amplifier.
 
No joy. I have lifted and reseated all the chips (there were 74, not 50) except for 3: the chipset (2 PLCC chips, I don't have a PLCC extractor) and the CPU which is seated very tightly against the socket and I couldn't even insert a very sharp blade underneath. Still no video output. I rigged an amplifier to the speaker out, no beeps.
 
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