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Unidentified Mainboard

Another Taiwanese XT clone of the era. Probably found under the "Unidentified" heading in th99. It's mentioned as part of a system sold by a vendor in Dennison, TX in the December, 1986 Computer Shopper
"Jumbo-640 (4.77 mHz) Mother Board w/OK ACT. 2070A RLL Controller 8087-2 (8 mHz) Math Co-Processor "

So now you know that it's a simple 4.77 MHz clone.

Nothing special--what's your particular question?
 
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The layout seemst to be exactly the same as IBM mainboard. Someone has removed the 8088 of the lower of the two sockets, and in the upper socket you can add the 8087 coprocessor.
 
This motherboard is installed in my PC-XT , and an accelerator card (image attached) is attacehd to the CPU socket.
Someboy know anything about this accelerator card? I also would like to know how to extract the contents of the ROMs.
 

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  • Accelerator 286.JPG
    Accelerator 286.JPG
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CPU should have been a 8088-2 = 8 Mhz.. So it was actually a turbo xt board.

Because 10 Mhz requires 120 nS memory. This board have 150nS. so the cpu would have been slower then 10 Mhz.\

200nS memory is for 4.77Mhz cpus.
 
Josper said:
OOps. Motherboard PROMS.
Click to expand...
'ROM7' will be the BIOS ROM. 'ROM3' through 'ROM6' are probably ROM's containing BASIC, possibly just copies of the Cassette BASIC ROM's found on IBM PC (IBM 5150) and IBM XT (IBM 5160) motherboards.

A lot of these Taiwanese XT clones are quite similar. At [here] is a diagram that is relevant. It is something that I created about 5 years ago for someone with a motherboard close to yours. The diagram almost certainly also applies to your motherboard. The information source for the diagram was the user manual at [here] in the X'GOLDEN BOARD section.
 
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