RT PC Memory Expansion

2MB Memory Expansion
4MB Fast Memory Expansion
8MB Fast Memory Expansion


2MB Memory Expansion P/N 6298286, no FRU

Note the "2MB ECC Memory" in the upper left corner.

Lots of 41256-15 chips, 40 per side. There are also logic chips within the ranges 1-50 and 73-120, so don't get excited.

Note the lack of any jumpers. Fast Memory cards have a jumper to set speed.

HMS says P/N 629928


4MB Fast Memory Expansion PN 61X7005

Looks to be set up for interleaved memory. M1-40 and M41-M80 are 65X5506ESD. The center chips are all logic.

This card is only used with the RT PC Advanced Processor Board. (Oh?)

The HMS says to identify this card, look for the "4MB Enhanced ECC Memory" printed on the option.

J3 HMS only shows this jumper in the "Fast" position. No explanation.

"When using 'Enhanced ECC memory' boards, make sure that the jumper on the memory cards is in the 'fast' position. The undocumented jumper allows the newer cards to work with the older processors by moving it to the 'slow' position.


8MB Fast Memory Expansion P/N 60X5777, no FRU

Same layout as the 4MB Fast Memory Expansion, but at least on this one, there is a sticker saying "8MB Enhanced ECC Memory" top center.

M1-M80 are 6470780ESD.

HMS says P/N 61X7009

J3 HMS only shows this jumper in the "Fast" position. No explanation.

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Louis Ohland, Peter Wendt, William Walsh, David Beem, Tatsuo Sunagawa, Jim Shorney, Tim Clarke, Kevin Bowling, Tomáš Slavotínek, and many others.

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 23 Oct 2021 - Changes & Credits | Legal Info & Contact