Article View: comp.sys.amiga.tech
Article #2179Re: Bus Latency
From: Chuck McManis
Date: Fri, 17 Nov 1989 23:12
Date: Fri, 17 Nov 1989 23:12
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1439 bytes
In article <322@blenheim.nsc.com> waggoner@dtg.nsc.com (Mark Waggoner) writes:
> ... The recent postings about dma vs. non-dma disk controllers mention
> that dma can be locked out for a long time when an overscan screen is
> being displayed, but how long is "a >long time?"
Given a 704 X 440 screen with some sprites, audio, copper and blitter
activity I'm pretty sure it is possible to lock out DMA for one full frame,
14mS at 60Hz.
Frame time = 16.6 mS but chip activity is concentrated during
the (220lines/frame)/(60 frames/second * 262.5 max lines/frame)
which equals 13.9 mS.
That would be slightly longer for PAL systems.
--Chuck McManis
uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@Eng.Sun.COM
These opinions are my own and no one elses, but you knew that didn't you.
"If it didn't have bones in it, it wouldn't be crunchy now would it?!"
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arc1-ca.pugleaf.net!utzoo!yunexus!ists!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!usc!apple!sun-barr!newstop!sun!pepper!cmcmanisReferences:
<322@blenheim.nsc.com>Show Full Headers
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Path: arc1-ca.pugleaf.net!utzoo!yunexus!ists!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!usc!apple!sun-barr!newstop!sun!pepper!cmcmanis From: cmcmanis%pepper@Sun.COM (Chuck McManis) Newsgroups: comp.sys.amiga.tech Subject: Re: Bus Latency Keywords: bus dma latency Message-ID: <128061@sun.Eng.Sun.COM> Date: 17 Nov 89 23:12:13 GMT Article-I.D.: sun.128061 References: <322@blenheim.nsc.com> Sender: news@sun.Eng.Sun.COM Reply-To: cmcmanis@sun.UUCP (Chuck McManis) Organization: Sun Microsystems, Mountain View Lines: 18