Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!tut.cis.ohio-state.edu!n8emr!uncle!oink!jep
From: jep@oink.UUCP (James E. Prior)
Newsgroups: comp.unix.sysv386
Subject: Re: X performance improved more by?
Keywords: X, ESIX, 80387, memory
Message-ID: <67@oink.UUCP>
Date: 13 Jan 91 01:59:35 GMT
References: <9788@b11.ingr.com> <2840@sixhub.UUCP>
Reply-To: jep@oink.UUCP (James E. Prior)
Organization: Random Prime Research Institute  Columbus, Ohio
Lines: 45

In article <9788@b11.ingr.com> richard@xanth.ingr.com (Richard Griffiths ) writes:
>     My question is, what will give me more of an X performance boost? 
> Added an 80387 math co-processor, or adding more ram?   A scarcity of
> funds makes this an either or question. 

X uses integer arithmetic.  The math chips are for floating point, not
helping integer arithmetic.  

You need to have enough RAM to avoid swapping, but that's all.  

80386 CPUs are general purpose CPUs.  VGA boards dump all the 
computational load on the host CPU.  Shifting, masking, and oring 
several bytes of data (to display character) is something that takes
several instructions on a general purpose CPU.  To speed this 
work, use a not so general purpose CPU or use a smarter video 
controller/CPU.  Replacing the 386 with a not so general purpose 
CPU is out of the question; we wouldn't be able to run the programs 
that we have.  Using a better video controller or CPU is the answer.  

There are many out there.  There are controllers, that look like
peripheral chips to the host, such as the NEC 7220, the Hitachi 63484, 
and the defunct Intel 82786.  They quicky do the low-level grunt work 
or graphics stuff, much quicker than the general purpose host CPU.  
There are graphics CPU such as TI's 34010.  They special purpose 
CPU, that have special instructions to do the low-level grunt work as 
quickly as the video controller chips.  

I do not want to start a holy flame war over the virtues over which 
video controller/CPU is better than the others.  

The point is that almost any video controller/CPU is better than none.  
Even if they aren't the latest and greatest.  At least they remove 
burden from the general purpose host CPU.  

For example, my obsolete Bell Technologies Blit Board that uses the 
defunct 82786, using crude RAM chips, beats the hell out of my 
modern VGA board for speed.  

If you are serious about wanting to do faxt X, then by a late model 
video board THAT IS ALREADY SUPPORTED WITH A DRIVER FROM YOUR UNIX
VENDOR, that has a graphics CPU.  

73 de
-- 
Jim Prior    jep@oink    osu-cis!n8emr!oink!jep    N8KSM