Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!xanth!mcnc!rti!xyzzy!giants!poirier
From: poirier@giants.dg.com (Charles Poirier)
Newsgroups: comp.sys.amiga
Subject: Re: 2090A card and hi-res screens
Summary: Yeah fine, but when?
Message-ID: <3843@xyzzy.UUCP>
Date: 6 Mar 89 23:31:46 GMT
References: <8903022014.AA25100@queen.csri.toronto.edu> <6138@cbmvax.UUCP>
Sender: usenet@xyzzy.UUCP
Reply-To: poirier@dg-rtp.dg.com (Charles Poirier)
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Organization: Data General Corporation, Research Triangle Park, NC.
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In article <6138@cbmvax.UUCP> jesup@cbmvax.UUCP (Randell Jesup) writes:
<In article <8903022014.AA25100@queen.csri.toronto.edu> drz@csri.toronto.edu (Jerry Zarycky) writes:
<>I am having trouble loading 640x400 4 bitplane screens from my harddrive.
<...
<>I realize that the card's software uses DMA to do the I/O and that it is
<>largely being soaked up by this sort of screen, but why does it slow down
<>to such an extreme crawl?
<
<	Because it has a 64-byte FIFO for buffering, and with 640x{200|400} 4
<bitplanes there are no free cycles for DMA while the beam is on screen, and
<it overflows often.

For me, "often" is 9 times out of 10, i.e. tenfold slowdown.  Oops.

<>I take it that this is a shortcoming with the software in the EPROMS.
<>So I ask Commodore "Will this ever be fixed?"
<
<	Well, I'd say the problem is with the hardware :-), but there are
<software workarounds we plan to implement when next we upgrade the driver.

Fine, but *when* will that be?  I've been waiting for a driver that fixes this
problem a good 8 months.  My 2090A is soon going sailing off a nearby cliff.

	Charles Poirier