How was written the Plus/4' O.S.? I'm wondering in which system/machine was really written, at time, the O.S. of the Plus/4 (and C16). If I'm not wrong there was any IDE nor compiler available. Anybody has more info?
Re: How was written the Plus/4' O.S.? As far as I know they were using VAX systems and cross-compile everything on them. Later (perhaps in the C128 era) they used Amigas. But I have to check in Brian Bagnall's books.