From: "Greg Holdridge" <greg AT holdridge7 DOT freeserve DOT co DOT uk> Newsgroups: comp.os.msdos.djgpp Subject: Re: PS: A mysterious event Date: Tue, 15 Aug 2000 10:37:24 +0100 Organization: Customer of Energis Squared Lines: 28 Message-ID: <8nb318$3f3$1@news7.svr.pol.co.uk> References: <8n6i6g$8cn$1 AT newsg4 DOT svr DOT pol DOT co DOT uk> <8n6ir5$8rp$1 AT newsg4 DOT svr DOT pol DOT co DOT uk> <8n8plk$ere$1 AT nets3 DOT rz DOT RWTH-Aachen DOT DE> NNTP-Posting-Host: modem-152.scandium.dialup.pol.co.uk X-Trace: news7.svr.pol.co.uk 966332264 3555 62.136.20.152 (15 Aug 2000 09:37:44 GMT) NNTP-Posting-Date: 15 Aug 2000 09:37:44 GMT X-Complaints-To: abuse AT theplanet DOT net X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2615.200 To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com Thanks a lot... I was aware word outs were unstable on some cards but I didnt know the issue was still... an issue.. Greg Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de> wrote in message news:8n8plk$ere$1 AT nets3 DOT rz DOT RWTH-Aachen DOT DE... > Greg Holdridge <greg AT holdridge7 DOT freeserve DOT co DOT uk> wrote: > > Actually, sometimes a SIGSEGV occurs instead of power off on monitor- this > > highlights that the problem occurs during a lodsw loop: > [...] > > .SetCRTParmsLoop: > > lodsw ;get the next CRT Index/Data pair > > out dx,ax ;set the next CRT Index/Data pair > > loop .SetCRTParmsLoop > > If memory serves me well, this method of accessing IO ports is known > to be dangerous, and known not to work, too. You're supposed to insert > short pauses between succesive accesses to the CRT ports, esp. on > modern CPUs. If you don't, you'll confuse the living daylight out of > the CRT chip. Loss of VSync (--> blank screen) would be easily > explained by that. > -- > Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de) > Even if all the snow were burnt, ashes would remain.