Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!netsys!scooter!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.sys.amiga
Subject: Re: OS/2 vs. Pournelle
Summary: Really about OS/2 portability, etc.
Message-ID: <1366@neoucom.UUCP>
Date: 12 Oct 88 15:18:03 GMT
References: <5384@fluke.COM> <9362@swan.ulowell.edu> <800@super.ORG> <Oct.2 <2759@sugar.uu.net>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 50


Peter was wrting about the hacks of OS/2 fitting to the Intel
arcitecture versus the relatively high portability of Unix
derivative operating systems.

Versus Unix derivatives, the apparent hackishness (is that a word?)
of OS/2 seems peculiar at first.  Part of the problem is that OS/2
has to go to lengths to be backwards compatible with regular DOS
hardware that wants to scribble randomly onto the video RAM and
things like that.  EGA and CGA video display adapters are pretty
stupid, and have fixed addresses for the display buffer.  This is a
pretty nasty thing to have to deal with when you are trying to
multitask two original flavor non-windowed DOS applications that
both are trying to scribble into the video RAM.  I don't know what
OS/2 does, but what Windows 386 does is apparently generate a page
fault when an application scribbles into the video RAM, and then
switches to single tasking mode until the miscreant task exits.
Yuck.

At least with Unix, good behavior is enforced from the ground up,
so writing a portable O/S is more straight forward, if not easier.
I got a chance to mess arond with the beta test version of AT&T's
DOS merge product running on a 6386.  DOS merge had to go to
extensive lengths similar to OS/2ishness to run DOS applications on
top of Unix.  As you might guess, graphic applications were quite
often able to trash the DOS emulator, but at least the Unix
underneath kept going.

I suppose that I should mention the Amiga since this is its group.
One nice thing that the Amiga has going for it is a very sensible
video architecture.  Now all we need to have is an mmu, so that we
can map the video display into virtual memory, and then use the
blitter to our advantage for managing what's on the screen.  Not
that we really are all that excited about multitasking misbehaving
DOS applications on our Amigas :-).  It really is too bad that the
poor IBM doesn't have nice video hardware.  That's the problem with
an evolutionary product like the PC.  You've got to assume least
common denominator hardware for anything you write.

Jerry would probably even agree.

--Bill
  ...!lll-winken!neoucom!impulse!wtm

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