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Auction: Defective IBM 61X6752 Microchannel Memory Expansion Card with 18MB Memory AS-IS

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Louis Ohland

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Nov 27, 2021, 4:23:01 PM11/27/21
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https://www.ebay.com/itm/265403130688

BIN / MAO

I'm not czeching on the particulars, but this card could not handle "18MB"

Each SIMM has 9 OKI M41256, 256KBx1 DRAM. So, that would be 8 total
256KB SIMMs, total 2MB?

https://ardent-tool.com/memory/IBM_Memory_Expansion.html#1_8MB

Is it truly defective, or is that they tried it inan incompatible system?

Chances are that it works.

WBSTClarke

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Nov 29, 2021, 9:09:40 PM11/29/21
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Sadly, IBM had their own "presence detection" arrangement for 30-pin SIMMs of 256KB or 1MB capacity (with Parity and gold-plated contacts). So-called "Industry Standard" SIMMs will be mis-identified as to capacity etc.

WBSTClarke

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Nov 29, 2021, 9:10:15 PM11/29/21
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http://john.ccac.rwth-aachen.de:8000/misc/ps2cache/

Louis Ohland

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Nov 29, 2021, 9:30:59 PM11/29/21
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Page 5 of the Mar 93 HMM has only a graphical depiction of the
individual chips on a 30 pin SIMM.
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