Dec Rainbow prehistory

From: Sean 'Captain Napalm' Conner <spc_at_conman.org>
Date: Wed Nov 19 19:31:51 2003

It was thus said that the Great Tom Jennings once stated:
>
> On Wed, 2003-11-19 at 16:24, Sean 'Captain Napalm' Conner wrote:
>
> re: int 20h
>
> > Why was it short sighted? ... Since the design was before MS-DOS,
>
> Oh oh... was it really? Is it possible that my mental chronology is
> corrupted? Gee, that's never happened before, erm, ugh...
>
> > when was the rainbow produced?
>
> I don't recall exactly, I'd guess 1981 or 1982.

  If it was introduced in 1981, I would say work was done at the same time
that the IBM PC and MS-DOS were being worked on; if around 1982 it might
have been the design itself predated MS-DOS but that any changes to the
system might be too expensive and the designers felt it would be an easy
thing to work around in software.

> > Also, DEC was primarily a minicomputer manufacturer so it may not be that
> > far fetched that engineers there might not be terribly familiar with state
> > of the art (hah!) microcomputer products at the time.
>
> Well... I lack sympathy here, still; obviously they were building
> machinery for this realm, it was beholden on them to know, as much as
> was possible then of course. DEC was very arrogant about CP/M-86 being
> superior; they told me as much many times.

  I'm not sure how system calls are made in CP/M-86, but I do know that
there were two ways to call DOS functions, via INT 21h, and through a call
to location $005 (in the PSP segment), which emulates the CP/M system
calling convention (which I think just did an INT 21h/RET, although
gratefully the memory is fading on that stuff).

> > -spc (When will this stuff dislodge from my brain? 8-)
>
> Never, it just changes shape :-)

  Heh.

  -spc (Mommy! Make it go away!)
Received on Wed Nov 19 2003 - 19:31:51 GMT