The memory for the ESI-4000 is harder to find than I thought. I purchased memory a few times without success. It just didn't work the way it was supposed to. The ESI wasn't seeing the whole memory amount or it just didn't work at all. Maybe I just had some bad luck. As a last resort, I went to Sweetwater Sound. They helped me upgrade to a full 128 Meg. (Be sure to request low profile Simms if you want room to install the effects board). Most people just throw in a couple of 16 MB simms. Let me tell you...having 128 MB of memory in my sampler has completely changed the way I make music. If you can ever possibly afford to max it out, you should do so. It's like having a 64 track recorder with full cut drag and paste.