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Path: utzoo!watmath!watnot!watcgl!fdfishman
From: fdfishman@watcgl.UUCP (Flynn D. Fishman)
Newsgroups: net.micro.amiga
Subject: I need an UltraFast Clock
Message-ID: <720@watcgl.UUCP>
Date: Sat, 24-May-86 13:56:59 EDT
Article-I.D.: watcgl.720
Posted: Sat May 24 13:56:59 1986
Date-Received: Sun, 25-May-86 16:08:05 EDT
Distribution: net
Organization: U of Waterloo, Ontario
Lines: 38


  Ok, here is the problem.

  I am working in C on a project for the psycology department here, and for
this program (in Manx C) I require an ultra fast clock.  The +/- 16.67
milliseconds is not fast enough, they want atleast a microsecond grain
so I can not use VBLANK or MICROHZ.

  I have tried using the current position of the Photon Beam as it scans the
moniter to fine tune VBLANK, and/or MICROHZ, but I find that VHPOSR seems
to be slightly offset from VBLANK and MICROHZ, so that every time the VHPOSR
wraps it changes its relative position to the clock, making timing inaccurate
for longer periods of time.

  I would like to try to avoid having to use only VHPOSR for the timer. 
i.e. counting the number of times the screen has been redrawn and then
calculating the time between events from the number of screen refreshes and
current Y-position.

  And while I am here anyways I have a question about a slightly related 
occurance.  When I read in VHPOSR and do the appropriate boolean to get 
the y-position I find that the series is a nice linear one i.e (1 2 3 4) 
from 1 to 255 except for between 7 and 10 where I get a 0 (i.e. 6 7 0 10)
does anyone know why?

   I would thank anyone in advance for the help on creating this UltraFast
clock, either with the method described above or by some other method.

I also apologize for not thanking some of the people who helped me with my
earlier problems but I am still having trouble emailing out (I will lick that
yet though)
-- 

      FDFISHMAN (Flynn D. Fishman)

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