Path: utzoo!attcan!uunet!cs.utexas.edu!samsung!usc!ucselx!crash!nkraft
From: nkraft@crash.cts.com (Norman Kraft)
Newsgroups: comp.lang.pascal
Subject: Re: Timing in Turbo Pascal
Message-ID: <5335@crash.cts.com>
Date: 29 Oct 90 16:08:13 GMT
References: <2280@oucsace.cs.OHIOU.EDU> <5307@crash.cts.com> <1990Oct28.142118.6756@maytag.waterloo.edu>
Distribution: na
Organization: Crash TimeSharing, El Cajon, CA
Lines: 26

In article <1990Oct28.142118.6756@maytag.waterloo.edu> dmurdoch@watstat.waterloo.edu (Duncan Murdoch) writes:
>>
>>Well, what they do, on an AT machine at least, is call a BIOS function which
>>waits for a millisecond. 
>
>Which version are you using?  On mine (5.5), all delay() does is run a 
>do-nothing loop.  The loop gets calibrated during the startup.  Maybe that's
>where you saw the BIOS call?  
>

On an 8088/8086 machine, the do nothing loop turns up, but on AT's there
is a BIOS function (used frequently by the Turbo Power folks...) that will
wait for one millisecond. Unfortunately, as previously stated, this call
does not result in very accurate timings. A do nothing loop is not very 
useful for timings, regardless of a variety of calibration algorithms,
and this shows up clearly with the TP 5.5 8086 timings. We had problem
after problem with this until we wrote our own timers.

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Norman R. Kraft	                           "Things should be as simple
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