<That was along time ago. Perhaps it was 56K rather than 48. All my CPM <systems, and I had several at the time, used 64K, though that's a small <difference nowadays. No, It's a result of knowing the machine and CPM and programming around it. The base distribution of CPM for that machine would not use memory above E800h due to the controller. It didn't meant it couldn't be there. If you didn't program around that the best you could do was 52k. All my other machines have 64k of ram or more. The practical aspect of it is that most apps 48k was plenty and only a few really wanted that little bit more. Oh the softsectro controller using the 765... The IO was also memory mapped into the FFF0->FFFFh segment of ram. that way I could use the more flexible memory ops that were also faster and also the controller could be co-resident. Allison