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From: bb@swamp.cis.ufl.edu (Brian Bartholomew)
Newsgroups: comp.sys.next
Subject: Re: Just what we need - PC programs for the NeXT
Message-ID: <25742@uflorida.cis.ufl.EDU>
Date: 5 Dec 90 02:55:53 GMT
References: <11920@milton.u.washington.edu> <25678@uflorida.cis.ufl.EDU> <1023@autodesk.COM>
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In article <1023@autodesk.COM> glang@Autodesk.COM (Gary Lang) writes:

> Well you have a good point. But there are other things to consider.
> The main mode of operation for a good piece of software is not an error
> condition but running under normal circumstances.  Suppose that not
> writing to memory meant unacceptable performance.  Would you be willing
> to trade a clean death of an application for those few times it crashes
> for blazing performance when it isn't crashing?

Considering all the various software I have used, on different
platforms at different times, I must conclude "no".  Almost every time
I have seen an application writer attempt to skirt the edges of this
trade off, they have ended up creating an application that is unusable
because it is unreliable.  Most of the time, when I have seen such an
application, I have suspected that the programming approach was not
one of careful weighing of alternatives, but merely unwillingness to
exert the effort to properly error-trap the code.  Besides, in the
land of Murphy's Law, there is no set of "normal circumstances".

> Part of the PC success story comes from the high degree of interaction
> afforded by performance tricks like writing to video memory directly.
> The perception of slowness has hindered large-scale accceptance of GUI
> platforms for quite some time. The systems now have pretty good
> performance even with large OO toolkits like NeXTStep, but it didn't
> used to bethis way.

You probably had a point back before 1985-ish (note the fast GUI
Commodore and Atari products created then) when the "PC"'s were toys,
but not any longer.  Now, a workstation-class machine holds the title
of "fastest" for perhaps 6 months, then is replaced by a machine twice
as fast.  Let's all stop coding applications as if our app was the
only code executing on the machine.

If Microsoft had written a decent ANSI.SYS (ANSI standard terminal
escape screen device driver) for DOS that wasn't done half-ass'ed and
slowly, apps could have skipped writing directly to screen memory in
the first place.  This would let products like a multi-tasking
simulator like AST's DesqView be implemented in a reasonable fashion.

One of the major problems with previous PC products was that the
system implementers created guidelines for applications and wrote
toolboxes, but then proceeded to break their own rules for thier own
apps.  Both UNIX and NeXT product implementations follow their own
rules, much to everyone's benefit.  When was the last time you saw a C
programmer replace stdio.h with their own package?

> Running OpenLook on my 16MB Sparc1+, I can safely say that the
> performance is unacceptable to an audience consisting of would-be
> former PC users.  That is to say, everything feels like a Mac 512K did
> 5 years ago. If Lotus has gotten around this by mucking with the system
> and made their application useful except in error conditions, I take my
> hat off to them.

Well, I completely disagree with your speed assessment.  I have
noticed that most "real" systems seem to fall between an apparent I/O
rate of 4800 baud, to 19.2 Kbaud.  Once the screen update gets faster,
users feel they can afford to install another layer of software and
functionality.

-----

Your comments seem to indicate that you disagree with the "overhead"
of an Operating System.  The purpose of an Operating System is to
enable shared use of resources, insulate you from other users, and
contain the damage from programs with flaws.  A user-level application
writing directly to screen memory prevents all of these from taking
place.  If you want a fast PC, get a 486.  I'll take a NeXT.

I'm tired of flaming DOS, and I expect the net is tired of listening.
Enough.


--
"Any sufficiently advanced technology is indistinguishable from a rigged demo."
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Brian Bartholomew	UUCP:       ...gatech!uflorida!mathlab.math.ufl.edu!bb
University of Florida	Internet:   bb@math.ufl.edu