Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!pasteur!ucbvax!hplabs!hplabsz!dleigh
From: dleigh@hplabsz.HPL.HP.COM (Darren Leigh)
Newsgroups: comp.sys.amiga
Subject: Re: OS/2 vs. Pournelle
Summary: os/2 does use protected memory
Keywords: OS/2 sucks OS/2 sucks OS/2 sucks OS/2 sucks
Message-ID: <2401@hplabsz.HPL.HP.COM>
Date: 29 Sep 88 23:51:44 GMT
References: <5384@fluke.COM>
Reply-To: dleigh@hplabsz.UUCP (Darren Leigh)
Organization: National Cholesterol Board
Lines: 46

In article <5384@fluke.COM> kurt@tc.fluke.COM (Kurt Guntheroth) writes:
>Here's a question I want answered...Do PS/2 (OS/2) machines have memory
>protection?  I don't mean software segments.  I mean hardware protection.
>Otherwise, you know what will happen.  The first OS/2 applications may be
>quite buggy and may have a tendency to wipe out memory, causing system
>alerts (we call them GURUs.)  What would Jerry think about GURUs from the
>Gods In Blue?
>
>In a year or so, Amiga may have serious revenge on Mr Pournelle.

OS/2 will run on any AT class machine (ATs, PS/2s and 386 boxes
running in emulation mode) that has enough memory (about 2 MBytes just
for the system if I recall -- I wouldn't try running with less than
4).  The 80286 operating in protected mode does have hardware
protected memory (thus the name) on a segment by segment basis.
Segments may be up to 64K bytes long (ha ha ha ha ha ha . . . ) but
can be smaller.  This allows you to have somewhat finely grained
protection until you run out of segment descriptors.  The protection
works OK for runaway programs, but not for security as I understand it
is easy to get around.  Oh, and Jerry's gonna love all those
protection violation errors he gets when he trys to write a simple
program in C, especially when the the OS spits them out for many
reasons.

By swapping segments to disk, OS/2 has "virtual memory" (derisive
laughter fills the background).  There are some problems though.
Since segments are normally 64K bytes in length (way too large) the OS
thrashes like mad, and since segments can be less than 64K bytes long,
the memory gets fragmented and the OS wastes time copying big chunks
of memory around.

The Presentation Manager is just a glorified version of MS Windows and you
have to be a lawyer to program it.  The OS/2 Software Development Kit
manual set is the most amazing thing I have seen:  the weight to
usefullness ratio approaches infinity.  Look, what can we expect from
lousy companies developing for a lousy machine.

When all is said and done, OS/2 certainly does beat MS-DOS.  But I
keep saying to myself: if only the Amiga had memory protection, if
only the Amiga had memory protection, if only the Amiga had memory
protection . . .

========
Darren Leigh -- I speak for myself, not the company.
Internet:  dleigh@hplabs.hp.com
UUCP:      hplabs!dleigh