RAM: 32 MB, expandable to 384 MB using SO-DIMM SDRAM (3.3V, unbuffered, 64-bit, 144-pin, 100 MHz or faster, 10ns) in two DIMM sockets (256 MB on top, 128 MB on bottom), top DIMM socket accepts 2" DIMM, bottom socket takes 1.5" DIMM
* The exact amount a Rev. A-D iMac can be upgraded varies from unit to unit. We have field reports of some models accepting 256 MB modules in both memory socket and reaching 512 MB - and other reports of early iMacs that won't work at all with 256 MB modules. There appears to be no way to know in advance whether a particular iMac will work with a certain sized memory module.