1) I built from parts two more IBM systems, one IBM stock dual drive 5150 PC and an IBM XT 5160. The XT has a ST 412 HD, with AST Six Pak. - 640K RAM and 10MB - who could need more than that? I put IBM DOS 3.3 on the HD.
2) I got my Northstar Horizon to boot using the ADM 3A terminal.
3) I have been able to successfully type in a lot of programs into my IMSAI lately (using CUTTER monitor program), and the system holds long enough to complete and run the program.