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Difference between expansion card RAM and motherboard RAM?

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First post, by keenmaster486

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The only way to increase the system memory on many 8 or 16 bit XT/AT systems is to use expansion cards.

Just talking about conventional memory here.

Does the memory on these cards appear identical to the memory on the motherboard from the CPU's perspective? Is there a difference in access time - extra wait states for example?

I'm asking this because I'm looking into "PC Sprint" solutions for overclocking a 5150 or 5160, and I'm wondering whether using an expansion card for RAM will be a hindrance to achivieving higher clocks.

World's foremost 486 enjoyer.

Reply 1 of 5, by wierd_w

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IIRC, on XTs and 286s, the ISA bus runs at the system bus speed anyway.

The issue is more with waitstates on talking on the expansion bus, than with the clock rate. That's my understanding, anyway.

Other possible issues with cache operation, i'd think.

Reply 2 of 5, by maxtherabbit

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On true IBM PC/XT the expansion card RAM performs identically to the motherboard memory. On the true AT, the same is also true provided you are using a 16-bit expansion card.

For turbo XT clones and AT clones it totally depends on the motherboard.

Reply 5 of 5, by keenmaster486

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I’m going to have to check my cards and see about the wait states.

In my 5150 I have an AST SixPakPlus, but I’m planning on putting a Monotech MicroRAM in a 5160.

World's foremost 486 enjoyer.

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