I've got RAM everywhere. How do I identify it?

Question

I've pulled RAM from a bunch of old PCs and I'm ready to find the largest modules to reuse. Most of it is just SDRAM but some of it doesn't have any identifiable markings that might explain it's size/speed.

I know these aren't large modules because they came off of machines that are quite old. One of them is a 500MHz machine. I just plan on reusing them for personal use.

Right now I have 4 modules (two of which appear to be the same). I'll just give you any identifiable markings and maybe you can explain what it means?

Exhibit A

• TOSHIBA
• 16Mx64 SDRAM
• PC100 - 222 - 620
• 16 large chips (8 each side)

This one appears to have 16 large, black "chips" (8 on each side). I think this means that each is 16MB and since there are 16 of them, that is a 256MB memory module?
Edit: I plugged it in and it only ends up being 128MB.

Exhibit B

• 8Mx64/72 SDRAM
• PC100 - 322 - 620
• 8 large chips (8 all on one side)

This one appears to have 8 large, black "chips" (8 on only one side). So... 8MB * 8 = 64MB module?
Edit: This one is properly identified as 64MB (confirmed by testing it)

Exhibit C & D

• 16 large chips (8 per side)
• The chips say: Korea, C006, 9745, FFF0, HM5126805TT10H

These have practically no other useful markings.
Edit: These appear to be 32MB each. Sad but true.

Answer 1

RAM chips are measured in bits, not bytes. So a 16Mx64 SDRAM is:

16Mbit x 64 / 8 bits per byte = 128MByte

Usually this information is on a sticker or on the PCB, and gives the size of the entire module. If it is printed on each RAM chip, then you need to multiply by the number of RAM chips.

Answer 2

Very old RAM indeed. On A & B You are correct, it is PC100 Memory (you won't be able to use this in any modern system and then 256MB and 64MB respectivly.

A wild guess given the other RAM you have is that yes, C&D are some form of PC100 in the 64-512 range.