PS/2 8550 memory upgrade?

[snq]

My PS/2 50Z currently has 1 MB of memory, and only 1 slot on the mainboard.

I'd like to upgrade the memory a little bit, so I tried a couple of SIMMs I had laying around. None of them worked, all I got was some error code. But I remember reading somewhere the max in these machines is 2 MB, the ones I tested with were probably larger than that.

Now the big question, what do I need to upgrade the memory? Can I use any 2 MB SIMM, or does it need to be some special kind? Is there any way to get say 4 MB (I know, huge! ) in it?

 

[dpatten]

You can't use bog standard PC memory in a 50z PS/2. There is a way to convert commodity RAM to PS/2 spec.

See http://www.mcamafia.de/mcapage0/memory01.htm


However, your best bet is to find a 16 bit MCA memory board on Fleabay and add memory that way. You can get up to 8MB.

Good luck!

 

[snq]

Thanks for the tip!

Someone offered me a SIMM with part number 65X6249.
Seems to be 2MB, 85ns, 72 pin. Supposedly for a model 55SX.

Any idea if this will work or should I just go straight for the MCA board?

 

[dpatten]

It sounds right, speed-wise (85ns) and its an IBM number.

Don't pay TOO much or it since you can pick up the MCA card for ~$25 US on fleabay

http://cgi.ebay.com/IBM-PS-2-MCA-16-bit-memory-expansion-adapter-8-MB-RAM_W0QQitemZ290307262321QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item290307262321&_trksid=p3286.c0.m14&_trkparms=72%3A1234|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50

 

[modem7]

According to Mueller's 'Upgrading & Repairing PCs' (first edition), 2MB is the limit for motherboard RAM on a 50Z, and the 2MB memory module is 85nS and was sold under part number 6450604 (at $1,395).

 

[Unknown_K]

I have a bag of PS/2 72 PIN simms and probably have a 2MB one of that type, but not worth shipping one to Sweden. They tend to have alot of small chips and gold colored edges unlike the cheap commodity RAM that has tin edges and few chips.

You are better off with a RAM card, unless 2MB is good enough for that PC.

 

[snq]

2 MB is better than 1 So far the only problem I've had with 1 MB is that I couldn't run Turbo C++ 3. Even Windows 3.1 runs with 1 MB, albeit with a lot of swapping when running an app.
I'm getting the 2 MB for free, but I don't want to have the guy go through the trouble of sending it if it's not going to work. But it looks like it will so I'll take him up on his offer.

I might max it out with 2 MB on the mainboard on another 8 MB on an MCA card and have a killer 286