17 Apr
2018
17 Apr
'18
1:49 p.m.
> OTOH, Micropro had 8080 originated Wordstar
running on the 5150 in weeks.
> It took them longer to edit the manuals than to port the code.
> Likewise Supercalc, etc.
On Tue, 17 Apr 2018, Warner Losh wrote:
Part of that too was because MS-DOS provided CP/M
programming interfaces,
so in many ways it was CP/M with a bag on the side...
Certainly.
But, Q-DOS didn't have much of a bag. It was mostly a rewritten copy of
CP/M with a different data structure for disk directory.
LATER, starting with MS-DOS 2.00, there was a major bag of sub-directories
and "unix style" file handling (file handles V File-Control-Block)
And much later, for "long filenames" (Win95), MICROS~1 used a kludge bag,
keeping the old 8.3 Directory structure and using "excess" directory
entries for storage of the long nicknames. HINT: do NOT use "long
filenames" for anything in the root directory.
WINDOWS itself started as a bag hanging off of the side. Originally,
MS-DOS clearly documented what was needed for a replacement command
processor. (Was it 2.11? or 3.00? when IBM removed the appendix from
the PC-DOS manual, and started marketing it as "PC-DOS Technical Reference
Manual" (still with "appendix" page numbering))
I always found it amusing that many programs (even FORMAT!) would fail
with the wrong error message if their internal DMA buffers happened to
straddle a 64K block boundary. THAT was a direct result of failure to
adequately integrate, or at least ERROR-CHECK!, the segment-offset kludge
bag. Different device drivers and TSRs could affect at 16 byte intervals
where the segment of a program ended up loading.
It was NOT hard to normalize the Segment:Offset address and MOVE
the buffer to another location if it happened to be straddling.
--
Grumpy Ol' Fred cisin at xenosoft.com