Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cwjcc!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.sys.amiga
Subject: Re: OS/2 vs AmigaDOS, 1.4wish, and more!
Summary: laughably slow IBM-compatible video boards
Message-ID: <1634@neoucom.UUCP>
Date: 15 May 89 15:55:25 GMT
References: <2134@iitmax.IIT.EDU> <5625@microsoft.UUCP> <5664@microsoft.UUCP> <2968@cps3xx.UUCP>
Distribution: na
Organization: Northeastern Ohio Universities College of Medicine
Lines: 22


Most IBM-compatible display boards are a study in slowness.  There
is considerable penalty being stuck in an 8-bit slot on the XT
interface bus.  The maximum DMA transfer rate on the XT bus is less
than 5 megabytes/sec.

The tightly coupled architecture of the Amiga graphics chips is a
substantial benefit.

Curiously, my IBM model 80-171 (16 MHz) machine has 25 wait states
on a video write according to the ATPERF progam.  Given the
piggyness of the display under windows 386 I'm inclined to believe
that.  You'd think IBM could have done better than that since that
model 80 VGA controller is integrated on the motherboard.

We recently switched some of our AT&T 6386s over to dual-port
VRAM VGA boards with 16 bit I/O.  Those cards are fast,
in fact qualitatively faster than the Amiga even under windows
386.  I haven't had the chance to ATPERF them yet.

Bill
wtm@impulse.UUCP