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From: cfejm@ux1.cts.eiu.edu (John Miller)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Animation
Message-ID: <1991Feb08.221509.3248@ux1.cts.eiu.edu>
Date: 8 Feb 91 22:15:09 GMT
References: <1991Feb7.093610.12594@ecmwf.co.uk> <1991Feb7.233344.7781@umiami.ir.miami.edu> <91039.125723CXT105@psuvm.psu.edu>
Organization: Eastern Illinois University
Lines: 27

In article <91039.125723CXT105@psuvm.psu.edu> CXT105@psuvm.psu.edu (Christopher Tate) writes:
>[ discussion on using TickCount to synchronize CopyBits to the vertical ]
>[ retrace interval, to avoid flicker.                                   ]
>
>Unfortunately, TickCount is only hardwired to the vertical retrace interval
>on Mac Plus/SE - type machines (possibly the Classic; I don't know).  On a
>Mac II series machine, the problem of multiple monitors rears its ugly
>little head -- which monitor's vertical retrace are you synching to?
>
>In fact, on a Mac II series machine, TickCount is anchored to an internal
>60.15 Hz (is that right?) clock which has absolutely nothing to do with
>the actual vertical retrace interval of any monitor.  In order to genuinely
>synchronize your CopyBits (or whatever) to a monitor's vertical flyback,
>you need to play some games with slot-based VBL tasks.
>
>The Usenet Mac Programmers' Guide (UMPG) has a good article, with code, on
>how to do just this.  As I recall the code is in C, but even if you're not
>comfortable with C it's probably a good place to start.
>
Where can one find this UMPG??

Thanks,

John Miller
Music Theory
Eastern Illinois University
CFEJM@UX1.CTS.EIU.EDU