Info on RAM for the 701C

[Norway Pad]

This post is for information only.

The background for this is that I posted a WTB for RAM modules for my 701C. But as no IBM branded known compatible modules were available on the marketplace, I had to go to eBay. I was at that point confused as to exactly what modules would work, and there was very little available information on the subject. Then Ray posted some really useful information there, and now that I have gotten the purchased modules verified, I decided to make a summary.

From the tabook, the 701C/CS was specified to use 92G7259 (4MB), 92G7261 (8MB), 82G7293 (16MB) or 92G7281 (32MB) 3.3V SODIMMs. Searching for those FRUs in the same tabook, shows that none of the other systems of that day referenced those part numbers.

The first three eBay auctions reference EDO (Extended Data Out) modules. In some cases, you can substitute an EDO module for an FPM, but usually not the other way around. The difference has to do with how the data out pins are controlled during "page reads". The short version is that FPM devices turn the output pins on and off from one address to the next, while the EDO devices do not.

Can the 701C tolerate EDO modules? From looking at several posts here in the forum it seems to be. The most important thing to note is that the module should use 2K refresh devices. This is basically identical to the difference between PC100 "low" and "high" density modules. So, to answer your question:

http://www.ebay.com/itm/200758250154 Micron MT8LDT432HG-6 should work, if that's what the seller is selling. That part number in the photo is for a 4M x 32 (16MB) FPM module using 2K refresh. Note that the auction title says "EDO" and "MT8LDT432HG-6X" (the "X" at the end stands for EDO). I would contact the seller before buying.

edit2: This one http://www.ebay.com/itm/321360365980 should also work. The Micron device is the same MT8LDT432HG-6; the 32MB module is EDO but uses 2K refresh. It might work, although both are said to be untested.

So I ended up buying the modules in the last edit2-auction, which is listed as "48MB-72pin-EDO-laptop-Memory-RAM-ASB-56RW832DZJ-6LS-C & Micron-MT8LDT432HG-6". In other words, 2 modules, one 16MB and one 32MB one. I have been a bit too busy to follow up on it, but tonight I sat down to test these two modules. And both of them works. The 32MB works flawless, and gives a total of 40MB RAM. The 16MB one threw a memory error at bootup, but the entire capacity was recognized, and Win95 ran like it should and reported 24MB RAM.

That's now one happy 701C.

NOTE: I might consider selling the 16MB module if anyone here in the Scandinavian countries needs it. Shipping it further away would probably be pointless.

[rkawakami]

A correction...

I had posted that the 32MB module in the eBay auction was EDO. In fact, it looks like it is FPM after all. The Hitachi HB56RW832DZJ consists of 16 pieces of 4M x 4 DRAM. It requires 2K refresh and outputs data in the standard Fast Page Mode operation. Sorry for the confusion but I can't remember why I thought it was EDO a few weeks ago.

ref: http://www.datasheetarchive.com/dl/Data ... 164637.pdf

[ilakast]

There's a new relevant ebay listing at the moment 111480911651

http://www.ebay.co.uk/itm/IBM-ThinkPad- ... 1480911651

[Norway Pad]

Ok, so the conclusion is that the 701 uses FPM and not EDO RAM. The price tag for this 32MB module seems pretty high compared to what I paid for mine. The advantage is that this module is tested and known compatible with the 701C, while I took a chance with the module I bought.