"CP/M compatible" vs. "MS-DOS Compatible" machines?

[Holger Veit]

Allison said:
> We can look back at CP/M and call it primitive but it was for the
> time a fair improvement and inovation.  One only has to look at the
> 8080/z80 DOS of the day and compare, There were few really viable
> choices that werent tied to a fixed hardware or non-portable.

>From the design, it looks as if CP/M was modelled after DECs RT-11. It
became fashion there to interpret everything as a named device; some of
these contained structured data - namely a file system (in contrast, Unix
had the complementary paradigm: everything is a file in a single rooted,
hierarchical name space, and some files are actually devices). RT-11 was
by magnitudes more evolved than CP/M and its children CP/M-86 and
PC/MS-DOS, when it comes to interrupt and DMA capabilities. The 8080 and
Z80 CPUs were equipped by Intel/Zilog with a rich set of support chips -
so it could have been done *right*. S-100 was not designed right WRT IRQ
and DMA; maybe this was one of the stumbling blocks.

-- 
Holger