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From: fsset@bach.lerc.nasa.gov (Scott E. Townsend)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Simple Frame Buffer boards
Message-ID: <1990Dec5.165513.16570@eagle.lerc.nasa.gov>
Date: 5 Dec 90 16:55:13 GMT
References: <916@boing.UUCP> <23699@grebyn.com> <918@boing.UUCP> <1411@mpirbn.mpifr-bonn.mpg.de>
Reply-To: fsset@bach.UUCP (Scott E. Townsend)
Organization: NASA/Lewis Research Center, Cleveland
Lines: 45

In article <1411@mpirbn.mpifr-bonn.mpg.de> p554mve@mpirbn.UUCP (Michael van Elst) writes:
>In article <918@boing.UUCP> dale@boing.UUCP (Dale Luck) writes:
>>I think the benefit far out weighs the cost.
>>I'd be glad to give up 1/8 of my
>>address space for a 1024x1024x8 frame buffer board. I think
>>it is a very small price to pay. I just don't see that many
>>people unwilling to give up 1M-2M of memory. It still leaves
>>4-6 megs of memory for programs as well as the 1M of chip memory.
>
>Hmm, I can't see much benefit from this besides ease of programming.
>IMHO, it is sufficient to map a smaller rectangular part. The drawing
>routines can be adapted without much peformance loss.
>
>What benefits do you think of ?
>
>Regards,
>-- 
>Michael van Elst
>UUCP:     universe!local-cluster!milky-way!sol!earth!uunet!unido!mpirbn!p554mve
>Internet: p554mve@mpirbn.mpifr-bonn.mpg.de
>                                "A potential Snark may lurk in every tree."

One benifit I can think of is indeed ease of programming, which also results
is a good size performance gain.  For example, a quick circle drawing
routine would slow down a fair amount if it had to worry about drawing
across this rectangular window into the real image.  This would be a lot like
clipping, which isn't a real quick operation.

A similar application would be in image processing.  Image segmentation by
boundary following would have to constantly check if it has gone past the
window boundary.

Essentially, one could say the reason I would like a flat memory space is
that I don't like the headaches a window has.  Headaches cause harder
programming, larger code, and usually measurably slower code.

I like the 680x0's simple address space better than the 80x86's segmented
address space too ;-)

--
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Scott Townsend               |   Phone: 216-433-8101
NASA Lewis Research Center   |   Mail Stop: 5-11
Cleveland, Ohio  44135       |   Email: fsset@bach.lerc.nasa.gov
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