I started restoring some files into my HP3000 emulator. First task at hand is getting MPEZ running again.
It was failing with unresolved externals SET’BREAKPNT and CLEAR’BREAKPNT. It seemed very odd to me that MPE stopped supporting this between the time my physical HP3000 was in production and whenever the O/S in this VM was released.
I relearned how to run the DECOMP decompiler and tracked down the missing calls in a segment called CCSCSEG0. This was one of the C compiler external libraries.
After puzzling for a while and looking around at various USLs I had, I managed to find MPEVNOPS.USL.EICS which had stubs for the missing procedures. I added these to a new SL specifically for MPEZ and up it came:
The last time I compiled MPEZ was 1995. 18 years later it is still running just fine even though the underlying hardware has completely changed in every way imaginable.
If only Microsoft would take a page from MPE’s book.