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From: oster@dewey.soe.berkeley.edu (David Phillip Oster)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Switching video pages on Mac Plus- How?
Keywords: video pages, alternative video page
Message-ID: <32367@ucbvax.BERKELEY.EDU>
Date: 5 Nov 89 02:15:18 GMT
References: <4296@blake.acs.washington.edu> <2805@jarthur.Claremont.EDU>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster)
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Organization: School of Education, UC-Berkeley
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In article <2805@jarthur.Claremont.EDU> wilkins@jarthur.UUCP (Mark Wilkins) writes:
>   Don't use tickcount.  Tickcount is often not updated strictly every 1/60
>of a second and there can be trouble if you use it for precise timing
>because disk accesses and cursor movement can prevent it from being updated
>before another vertical retrace interrupt happens.
>Using the Time Manager will allow a routine you indicate to be called in an
>amount of time which can be specified precisely to the millisecond. 

Time Manager is no better. If I wave the mouse around, I can get time
manager times to vary by about 10% over a 10 second interval.  Some early
programs soved this by turning off the mouse while doing time critical
things. (The SoundCap audio digitizer comes to mind.)