31 Dec
2022
31 Dec
'22
12:56 a.m.
On Fri, 30 Dec 2022, Paul Ruizendaal wrote:
One could argue that one of the drivers of the success
of CP/M in the
1970’s was due to its clear separation between the boot rom, BIOS and
BDOS components. As far as I am aware, Unix prior to 1985 did never
attempt to separate the device drivers from the other kernel code. I am
not very familiar with early Xenix, it could be that Microsoft had both
the skill and the interest to separate Xenix in a standard binary (i.e.
BDOS part) and a device driver binary (i.e. BIOS part). Maybe the
differences in MMU for the machines of the early 80’s were such that a
standard binary could not be done anyway and separating out the device
drivers would serve no purpose. Once the PC became dominant, maybe the
point became moot for MS.
Certainly Microsoft *did* have an operating system, as early as 1981, that
had the concept of separated BIOS and BDOS, but they didn't write it, they
bought it 🤪
That said, given that it existed in MS-DOS, I can't imagine it wouldn't
have been impossible to also implement in Xenix...
-uso.