Re-compiling old DOS

From: Allison J Parent <allisonp_at_world.std.com>
Date: Thu Jul 16 22:50:05 1998

< running on another computer (the same way they wrote BASIC for the Altair)
< Would they have waited to receive a beta unit to test/develop it live afte
< months of writing blind code based on IBM's specifications documents?

Likely they used a intel MDS800 running asm86 or PLM86. They could run
on intel ISB86 systems (multibus 8086 based). the 8086 was introdued in
'78 and available in '79 so hardware was not a problem. Heck they could
ahve used a Seattle Computers S100 8086 crate.

< it to DOS6 code, it seems like the DOS1 boot sector loads both BIO and DO
< back-to-back in memory (producing a single image, if you will), and then
< jumps to BIO. DOS6, in comparison, the boot sector loads IO, which then
< loads DOS.
<
< Any thoughts? I felt this qualifies as "classic" since the file dates
< are May 7, 1982 <g>

The monolithic load is an artifact of the CP/m heritage in general and
specifically CP/M1.4. It's effect was to make loading drivers difficult.
That resulted in later version loading the IO which is more extensable and
then using the io to load the DOS. I may add that CP/M2.x put more of the
burden in the bios and also seperated the load preocess more. Parallel
development.

Allison
Received on Thu Jul 16 1998 - 22:50:05 BST