According to this specification sheet (not sure of its correctness), it uses a fairly common IBM IC25N020ATD series 20GB 2.5" HDD. I don't have the exact model but I've got a couple of IC25N020ATCS04-0 and they are just plain PATA HDD of that era.

Could you explain a bit more about "didn't fit?" Better yet, read an article named How To Ask Questions The Smart Way first.

Everything I dug up says it uses a standard 2.5-inch PATA drive, though I have no information about drive height.

It is indeed a common 2.5" IDE 20GB disk, nothing special about it. There was no other option available, just keep in mind that the BIOS has the 32GB limit.

dormcat wrote on 2021-07-31, 11:32:

According to this specification sheet (not sure of its correctness), it uses a fairly common IBM IC25N020ATD series 20GB 2.5" HDD. I don't have the exact model but I've got a couple of IC25N020ATCS04-0 and they are just plain PATA HDD of that era.

Could you explain a bit more about "didn't fit?" Better yet, read an article named How To Ask Questions The Smart Way first.

the 160GB PATA drive i put in it were not detected. is there any way to flash the bios so it detects larger drives?

Oops i didn't push the drive all the way in. I am actually stupid.