Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mcnc!uvaarpa!murdoch!mendel.acc.Virginia.EDU!pts
From: pts@mendel.acc.Virginia.EDU (Paul T. Shannon)
Newsgroups: comp.sys.next
Subject: Re: Just what we need - PC programs for the NeXT
Message-ID: <1990Dec1.190910.19687@murdoch.acc.Virginia.EDU>
Date: 1 Dec 90 19:09:10 GMT
References: <1990Nov28.234910.28347@murdoch.acc.Virginia.EDU> <11920@milton.u.washington.edu> <25678@uflorida.cis.ufl.EDU>
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Ireallyam: pts

In article <25678@uflorida.cis.ufl.EDU> bb@loggerhead.cis.ufl.edu (Brian Bartholomew) writes:
>
>In article <1990Nov28.234910.28347@murdoch.acc.Virginia.EDU>
>pts@mendel.acc.Virginia.EDU (Paul T. Shannon) writes:
>
>> For those curious, or skeptical, I want to do this so that I can use
>> the entire display, with as little interference and overhead as
>> possible, to present full-screen visual stimuli for experiments in
>> perceptual psychology.
>
>-----
>
>In article <11920@milton.u.washington.edu>
>wiml@milton.u.washington.edu (William Lewis) writes:
>
>[Discusses a sicko PC-style direct-screen-memory access method that
>throws away memory protection, eliminates restoration of revealed
>window areas, breaks multiple-program access to the screen, throws
>away portability to other NeXT machine and OS versions, eliminates the
>printer, and generally requires a much more skilled programmer to
>write a much more picky and detailed program that is much less
>reliable.]
>
>Writing trash like this may be acceptable for PC's running Windows or
>Mac's running finder.  However, garbage like this is not acceptable
>for modern UNIX workstations, *especially* ones shipped with the
>premier window-system-development tool on the market.  

As the originator of this topic, perhaps it's my place to reply.

I agree with the sentiments of the poster, though I propose that
they don't address the issue, *my* issue.  I respect
standards, and I spend a lot of my programming time writing 
careful, portable code.  I admire the people who created NeXTstep,
and their work, I *use* it, and I ususally obey the rules
religiously.

Nonetheless, it's my job to write software to run experiments
in psychophysics.  This demands that stimuli, either auditory
or visual, be presented for precise and repeatable amounts of time.  

For a number of years I've used Masscomp's Real-Time Unix,  which 
runs in tandem with a dedicated, single-tasking graphics processor, 
and allows for such precise control.  Masscomp (now Concurrent) equipment
however, is very expensive to buy and maintain.  The annual maintenance
fee on our  68020, 4mb, 80mb disk system is more than the cost of
a single NextStation.  To add a disk, or NFS, will cost us a lot of
money.

Then along comes the NeXT: a great system at a great price.  It
looks like I can use it as it was intended, to write well-behaved
programs, and to use a burgeoning amount of 3rd party software.
And it looks like I can adapt it so that I can get my experiments 
written and running.

Maybe this will persuade you that there are times when it's not
always stupid to break the rules.  (I'm reminded of the jazz musician
who said:  'You spend 10 years learning your instrument, then 10
years learning the music, then you forget all that sh.t').
I can't hope to do precise animation if I let the update  program
do a disk sync (flushing dirty buffers to disk) every 30 seconds.
But I can do it if I can run as root, eliminate unnecessary daemons,
suspend update completely, maybe run in single user mode, and 
gain direct access to display memory.  You probably see this as "trash"
and "a sicko PC-style" , but I see it as compromises that may help
me to get my work done.

I'm not writing commercial software. I think you missed the point.
If you still disagree, I'd like to hear why.

 - Paul Shannon
   pts@virginia.edu