Which memory SIMMs will work in a PC-AT?

[djfitzgerald]

Over in this thread, people were talking about how PC-ATs appear to be picky about which kind of memory SIMMs that they recognize. Is there a definitive list of what types of SIMMs work in a PC-AT, or is it just a game of Russian roulette (ie: buy 1MB SIMMs on ebay, pray that they work)?

I know that some early model PS/2 machines (such as the model 30) needed to use proprietary IBM SIMMs. Seeing as my IBM Enhanced Memory Expansion Adapter is from the same time period, I fear that is also the case. However, the IBM documentation on the card doesn't say anything to indicate as such. But I'm in the situation (as the folks in that thread were before me) where the only SIMMs that appear to work in the card were the ones sitting in it when I bought it on ebay.

 

[Timo W.]

Do you mean the 5170 with "PC-AT"? That one doesn't even work with SIMMs. It's using DRAM chips, not memory modules.

The thread you linked to talks about memory cards. It's up to the individual memory card what SIMMs are supported. However, with parity (9-bit) and <80ns, you are mostly on the safe side.

 

[djfitzgerald]

Do you mean the 5170 with "PC-AT"? That one doesn't even work with SIMMs. It's using DRAM chips, not memory modules.

The thread you linked to talks about memory cards. It's up to the individual memory card what SIMMs are supported. However, with parity (9-bit) and <80ns, you are mostly on the safe side.

I do mean the 5170 PC-AT. And it does work with SIMMs, provided you have an IBM Memory Expansion Adapter or an IBM Enhanced Memory Expansion Adapter. But I made the question specific to the AT instead of to the MEA or EMEA themselves because at least one person in that thread (if I read it right) talked about running into the same problem with other AT-class memory expansion cards that took SIMMs.

 

[djfitzgerald]

Here's the quote:

Decided to futz around with it a bit more before calling it quits for the night, and I have to revise some of my earlier statements, which were based on previous experience and my memory (no pun intended) is being called into question...

Using other SIMMs in the place of the pair that came with the card will NOT work; only the pair of 9-chip Hitachi HM511000AJP12 SIMMs will work in this IBM expansion card.

The Boca Research memory card I have WILL work in the system... but ONLY with the above mentioned SIMMs, the Hitachi HM511000AJP12; any other 9-chip 1MB sticks in my possession will NOT work in my PC-AT 5170, regardless of the expansion card used.

So my problem is not with the card itself, but with the type of memory I'm using; apparently my 5170 is rather picky in such regards. But I can't seem to find anything special about this Hitachi memory when compared to my other available sticks (Mitsubishi 'm5m41002bj' and Fujitsu '81c1000a-60'). All are described as "fast page DRAM" and have very similar timing speeds and specs. They're all 9-chip which means they're parity (right?).

But without access to other SIMM's, this also means my efforts to expand the memory in this dinosaur have come to an end. I have some 4MB SIMMs and a plethora of 256 and 512K, but am quite certain they won't work.

This has me scratching my head. Any input in regards to this?

 

[Timo W.]

And it does work with SIMMs, provided you have an IBM Memory Expansion Adapter or an IBM Enhanced Memory Expansion Adapter.

Yes, that's the point. You can use SIMMs on memory cards, but not on the 5170 itself.

As written above, with parity (9-bit) and <80ns, you are mostly on the safe side. If you stick to modules from that time frame, even more so.

The Mitsubishi 'm5m41002bj' he used are most likely EDO or something and are not going to work. You will always find modules that are not working, not only when it comes to memory cards used in a 5170. Nothing to worry about.

 

[1ST1]

EDO always was delivered as PS/2 modules, tooo new for a 5170 era PC and memory card. There you only find 30 pin sims. and usually yes <80ns, parity (9 or 3 memory chips per module), 256 or 1 MB per module, and you are on the safe side. (in total more than 4 mb is a waste for a 286 AT)