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From: Daniel Phillips <phillips@arcor.de>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [ANNOUNCE] New PC-Speaker driver
Date: Thu, 15 Aug 2002 13:28:03 +0200
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Cc: vda@port.imtp.ilyichevsk.odessa.ua, Andrew Rodland <arodland@noln.com>,
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On Thursday 15 August 2002 12:57, Alan Cox wrote:
> There are easier equivalent ways to accurately measure the IRQ
> behaviour. Flip the state of a parallel port pin when you mask
> interrupts. You can even slap an oscilloscope on it that way

Right, I'll just go get my oscilloscope now...

In fact I relied on the technique you mentioned a great deal when
I was doing realtime work with PCs.  With a multi-trace digital
scope the effect is something like a poor-man's logic analyser
with a resolution of 10 us or so.

Another technique I can recommend highly is panicking by halting
in a tight loop with the speaker set to emit some tone.  It may
be annoying for the guy at the next bench but in some code, such
as transitioning to/from virtual86 mode, there aren't a lot of
alternatives.

-- 
Daniel
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