Need a little help with older 30-pin/72-pin memory setup

[kranky]

I'm trying to get my old PC into good enough shape that it will be OK for someone else trying to learn to use PCs. I don't know a heck of a lot about memory types.

The motherboard is a M-Tech R407e and has (8) 30-pin SIMM slots and (2) 72-pin SIMM slots. I currently have (4) 4mb and (4) 1mb 30-pin SIMMs for a total of 20MB. So the 30-pin slots are full, and I have (2) 72-pin slots to use. The CPU is an AMD 486-133 so it runs Win95 decent enough.

A friend gave me 2 16MB 72-pin SIMMs which don't work. The mobo manual implies certain 72-pin chips would have to be single-sided and others double-sided. Looking at the SIMMs, there are chips on both sides so I assume they are "double-sided", and the manual doesn't show any combination that uses 16MB double-sided 72-pin chips, and I assume that's why it doesn't work.

The relevant pages from the mobo manual: first page, second page. Only certain combinations of memory will work, apparently, according to the manual. Overall specs on the mobo are here.

My question: should I try to trade what I have for 16MB "single-sided" 72-pin SIMMs, or do something else? The only combination that will let me use the 30-pin chips I already have is a 36MB setup that would require adding (1) 16MB single-sided 72-pin chip. I'm just trying to get at least 32MB of RAM in this thing as cheap as possible because I'm just going to donate it anyway.

Thanks in advance.

 

[Lvis]

Have you removed the thirty pin and tried it just with the 72? Many boards couldn't do both at the same time. (some could though)

 

[drewski]

Holy mother of expansion ports! Is that 8 ISA slots I see?

One thing, are you sure the 72-pin simms you have are Fast Page? They could be EDO. Looked like from the description, only FPM memory is supported.

 

[nam ng]

"A friend gave me 2 16MB 72-pin SIMMs which don't work. The mobo manual implies certain 72-pin chips would have to be single-sided and others double-sided. Looking at the SIMMs, there are chips on both sides so I assume they are "double-sided", and the manual doesn't show any combination that uses 16MB double-sided 72-pin chips, and I assume that's why it doesn't work"

Practically all older 486 MOBOs with both 30 and 72 pins slots only support 5V DIMMs, newer 72 pins DIMMs are usually 3V types won't work, some will function in 3V slots though will suffer total failure rather quickly.

 

[kranky]

L vis, yeah, I did try it with just the 72-pin chips. Nothing. According to the mobo manual, you can use both types in certain combinations (the links in the first post).

drewski, you're right - 8 slots, no waiting. Looking at the chips, I don't see any markings that would indicate if they are EDO or FP, and that could very well be the problem. I've been looking around to see where I could look up online the type of chip by the chip number, but didn't have any luck. The only marking on the board itself is CW74420-A. The chips are marked CW417404-6.

nam ng, the manual doesn't say anything about voltages, so perhaps the mobo does require 5V chips. I might have already fried them, but might still look around to see if I can get something that fits.