Author here. Yes, there were many more. Some were forms of BASIC, others were just unique systems. The issue for me was to decide which to list, and which not

Author here. Yes, there were many more. Some were forms of BASIC, others were just unique systems. The issue for me was to decide which to list, and which not to. For the most part, I went for ones that were most used. Ones that were built into BASIC I treated as BASIC and did not include. Most of the others were either replaced by the manufacturers with later systems, or were replaced by CP/M. This happened even for systems in the 70s. I have a Heathkit that originally shipped with “HDOS” and Heath later made available CP/M. Starting with 1.3, then 2.0 and then 2.2. The ones on mainframes I included due to TOPS-10 being the birth place of CP/M and therefore MS-DOS, DR-DOS, and FreeDOS. As the DECsystem-10 didn’t arise in a vacuum, I felt it necessary to include those earlier mainframes with DOSs.