Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!gatech!uflorida!loggerhead.cis.ufl.edu!bb
From: bb@loggerhead.cis.ufl.edu (Brian Bartholomew)
Newsgroups: comp.sys.next
Subject: Just what we need - PC programs for the NeXT
Summary: Gaack.
Message-ID: <25678@uflorida.cis.ufl.EDU>
Date: 1 Dec 90 08:00:12 GMT
References: <1990Nov28.234910.28347@murdoch.acc.Virginia.EDU> <11920@milton.u.washington.edu>
Sender: news@uflorida.cis.ufl.EDU
Distribution: na
Organization: UF CIS Dept.
Lines: 59


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.  I have noticed
that the Lotus people broke the Sun version of 123 the same way, by
explicitly going out of their way to write directly into screen
memory.  As a consequence, when this program hangs as it does
occassionally, your window manager (SunView) is shot dead in the
water.  Will people never learn?

> Sigh, the price of portability is control.

Incorrect.  With some trivial Postscript, you may write to any pixel
in any window you open.  However, you do not give up any features of
DPS or NeXTStep.

> Flames about portability and philosophy to /dev/vid0.

I did this, but it wrote trash all over my screen, and then crashed my
window manager and hung my machine.  Too bad I was not protected by
all the memory protection and multitasking cooperation carefully
designed into UNIX and the window manager in the first place.  Of
course, you can expect any program that uses this method to be equally
reliable.

-----

Please see article <11902@milton.u.washington.edu> by
wjs@milton.u.washington.edu (William Jon Shipley), earlier in this
group, for a proper method to accomplish this goal.


--
"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