Two tracks between pads - you'd never do that by hand!

About the PCB design: the Enterprise motherboard how designed? By hand or PCB software on - for example - IBM PC?

I'm guessing given the quality of the motherboard it was routed 'by hand' using some design software. Auto routing traces even now is pretty rubbish compared to what a person can do.

It's also weirdly relaxing routing traces yourself...

Bruce!
GUS found two undocumented keywords in the IS-BASIC: PRIORITY and PROTECT.
Do you have any memories about these?

These are stored in the Segment 1 part of BASIC. The PRIORITY only in the 2.1 version.
SET PRIORITY n set the value of EXOS variable 38 - SPRITE (which are exist only in EXOS 2.1+).
I guess the PROTECT for the variable 34, but don't working. Probably some bug there?

I guess the PROTECT for the variable 34, but don't working. Probably some bug there?

Working SET TAPE PROTECT n
Interesting. Why is it missing from the BASIC Manual? Only the TAPE LEVEL and TAPE SOUND are documented. But the EXOS manual talking about it.

Bruce! Can you remember the original error messages how definied? It is a big meeting where all programmers talked about which errors possible and what is the right messages?
Or everyone just wrote the program and when definied a new error situation then add new error code and message?

The latter - we didn't do big meetings! We were all working in the same big room so it was all very informal. The EXOS error codes (.XXX) were in an include file. We used a makefile system so whoever added a new code was unpopular because it caused everyone's files to reassemble!

I made the message text up as we went along, possibly modifying existing messages to keep them all consistent. As ROM space was short they had to try and be terse while still being reasonably user-friendly.

*** milk not found

*** just made up one day to make the errors stand out

*** as a no op came much later in the light of using the editor in real life

B.

Interesting question from lgb: IS-DOS are only running enviroment for the CP/M and also original CP/M code included?
Or a complete new OS which are only compatible with CP/M at function calls? And not used any code from the Digital Research?

No original CP/M code in there - it's a complete fresh OS that is compatible at the function call level (all the file I/O with FCBs, search for first/next etc, character I/O). I don't know how often this compatibility was used - I don't remember any bug reports to do with incompatibilities with CP/M programs, but maybe you know different after so long! There is certainly scope for incompatibilities with undocumented FCB fields because EXDOS uses them to support sub-directories, which CP/M doesn't. Also any low-level disk accessing such as formatting will be different of course.

And it is also compatible with MSX-DOS? In the documentation write "MSX compatible" at many function calls.
Unfortunately I never seen any MSX DOS programs.

Yes but I don't think it was a big deal - MSX-DOS was based on the CP/M function interface too. I expect there were some extra function calls but I can't remember the details. (Now we're on the subject MS-DOS was pretty similar too even though it's on a different processor!)