>> Sorry, I missed the first part of this thread. Is this MBasic for DOS?
No, no ... I never even thought about DOS. Since the problem was coming up on Josh's 8080 card, I assumed CP/M. At least that's where I was running my tests.
>> If so, don't you need **genuine** boot ROMs to make MBasic work properly?
I believe you are right. I think DOS MBasic used some of the code (subroutine calls) in the on-board ROMs.
Roger