On 7/31/2023 6:01 AM, Paul Edwards via Freedos-devel wrote:
I never knew why DOS only had ANSI for output, not input.
That is not co correct. And it wouldn't be as much a DOS issue, but an
issue with the ANSI driver being loaded. Beside the very early days of
DOS, with it originally being conceived (as DQOS/86-DOS) by SCP for
their S100 based 8086 system, starting with DOS 2.0, ANSI would handle
both input and output, as you have to use a serial terminal to
communicate with your system.
The IBM PC (and +99.99% of all clones) used direct hardware access in
it's BIOS for keyboard handling and direct memory access ultimately for
screen output. Though there were a handful of early, "not so IBM
compatible" PCs, likethe Sirius 1/Victor 9000, the DEC Rainbow 100 and
probably a couple more (early Zenith).
And I used to use/write software for some "industrial" PC in 19" racks
that were operated via serial connected terminals.
Any software that uses just DOS calls should run on any other PC. If
that machine is not "IBM compatible", than DOS will have to be adapted
to that specific hardware, either by using appropriate BIOS calls (if
available) or needs to have that DOS calls adapted to access the
underlying hardware directly.
Beside those early S100 computers (or Heathkit IIRC), ANSI was only
necessary on PCs/DOS based systems when using terminals, for example
things like IBM 3270 (where the connection was made via a special
adapter card). Or BBS systems, in the days before the Internet existed,
over slow dialup connections...
The problem (and the competitive edge for software) is that DOS calls,
even BIOS and also ANSI sequences are excruciating slow, compared to
direct hardware access. That was a decisive factor as to why IBM
prevailed, even though contemporary machines like the Sirius 1 or TI
Professional had technological advantages (CPU was almost the same, 5MHz
8088, but max RAM under DOS were 896KB and 768KB respectively, the
Sirius 1 had out of the box 800x400 monochrome graphics, the TI Pro had
720x300 in either mono or graphics, the Sirius 1 had 1MB floppy disks,
while the first IBM PC had only 160KB). All clones, that wanted to get a
piece of the PC market pie had to follow the IBM hardware layout, And 40
years later, this is still the norm, though things like BIOS support
have already been deprecated, and that's also something where no ANSI is
going to help you, specially when all "modern" systems are GUI based...
Ralf
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