4 ms·

And arguably more file loaders than operating systems as such. I long thought it a sort of interesting question how things could have turned out differently if

by ghaff 2y ago

And arguably more file loaders than operating systems as such. I long thought it a sort of interesting question how things could have turned out differently if one of the many 16-bit operating systems (or Unix of course) kicking around in the minicomputer world had been more widely used on early PCs.

dfawcus 2y ago
Some of the products mention on that piece were true operating systems. MP/M and its derivatives (MP/M-86, CCPM, CDOS) were all multitasking, multi-threading, multi-user, multi-terminal/console real time preemptive OSs. The bank switching versions also had a form of memory protection. CDOS-68k, CDOS-286 and the subsequent renamed to FlexOS products also had those capabilities, but with inherent memory protection. So it is only really the basic CP/M-86 product (lacking the MP/M bits) which was the simple program loader. In many ways the FlexOS product are sort of inspired from the DEC minicomputer RSX-11m OS; and the MP/M derivatives look like they were inspired by DEC RSX-11d (and hence RSX-15).
- ghaff 2y ago
  Fair enough. I suppose that hardware resource constraints were sufficiently tight at the time that the "mass market" wouldn't have thanked you for something that might have cost twice as much (at a time when micros were already quite expensive relative to today).
- nickdothutton 2y ago
  I was an MP/M 2 user (Altos) for a while. It was a great system for a small workgroup, supporting a handful of (Volker Craig) Terminals. VT-52 clones IIRC.
rbanffy 2y ago
> And arguably more file loaders than operating systems as such That's a bit unfair. They also provided file operations and hardware abstraction. That way, it didn't matter how your disk IO was implemented (CP/M on Apple II's used the 6502 for that) and your code could be exactly the same.

4 ms·

And arguably more file loaders than operating systems as such. I long thought it a sort of interesting question how things could have turned out differently if

by ghaff 2y ago

dfawcus 2y ago
Some of the products mention on that piece were true operating systems. MP/M and its derivatives (MP/M-86, CCPM, CDOS) were all multitasking, multi-threading, multi-user, multi-terminal/console real time preemptive OSs. The bank switching versions also had a form of memory protection. CDOS-68k, CDOS-286 and the subsequent renamed to FlexOS products also had those capabilities, but with inherent memory protection. So it is only really the basic CP/M-86 product (lacking the MP/M bits) which was the simple program loader. In many ways the FlexOS product are sort of inspired from the DEC minicomputer RSX-11m OS; and the MP/M derivatives look like they were inspired by DEC RSX-11d (and hence RSX-15).
- ghaff 2y ago
  Fair enough. I suppose that hardware resource constraints were sufficiently tight at the time that the "mass market" wouldn't have thanked you for something that might have cost twice as much (at a time when micros were already quite expensive relative to today).
- nickdothutton 2y ago
  I was an MP/M 2 user (Altos) for a while. It was a great system for a small workgroup, supporting a handful of (Volker Craig) Terminals. VT-52 clones IIRC.
rbanffy 2y ago
> And arguably more file loaders than operating systems as such That's a bit unfair. They also provided file operations and hardware abstraction. That way, it didn't matter how your disk IO was implemented (CP/M on Apple II's used the 6502 for that) and your code could be exactly the same.