S1100 uses custom memory Akai part #EXM005 (2Mb card) and #EXM008 (8Mb card). 2Mb stock (one EXM005 installed into one memory slot) - 4 memory slot ( requires dip switch to be changed to install more memory ) - can be updated to 32Mb via four 8Mb expander boards (EXM008). You can mix any combination of EXM005 and EXM008. Memory is displayed in Megawords which equals 1/2 the amount of megabytes. EX: Four Megawords = eight Megabytes.