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From: donw@zinfandel.UUCP (Don White)
Newsgroups: net.micro.amiga
Subject: Re: Problems with the MICROHZ timer (medium length).
Message-ID: <526@zinfandel.UUCP>
Date: Mon, 11-Aug-86 16:34:46 EDT
Article-I.D.: zinfande.526
Posted: Mon Aug 11 16:34:46 1986
Date-Received: Thu, 14-Aug-86 05:53:54 EDT
References: <694@psych.uq.oz>
Organization: Zehntel Inc., Walnut Creek CA
Lines: 34

> Brief background: (512k, Version 1.1)
> 	I am attempting to use an Amiga for reaction time studies involving
> six inputs which come from various types of switches connected to the mouse
> ports.  After realising that here in Australia, the system timer gives only 
> 20ms resolution (and is "changed every time someone asks what time it is" ),
> I attempted to use the MICROHZ timer to give more accurate times.
> Although the RKM doesn't mention it, it seems reasonable to be able to issue 
> a CMD_READ after adding a time request to get a "count down" value.  Using 
> some procedures below, this is what I attempted. 

   I would think the most accuracy would be acheived by using forbid to stop
all other tasks, then perform assembler timing loops. I would think that this
would be the only way to be sure of accuracy. i.e. I would think it NECESSARY
to temporarily step on multitasking.

   Your assembler loops could time out after a few seconds to give back user
control. 

  This approach would be fast, efficient, and (I would think) fairly painless.  
It would also give you reaction times with a resolution of maybe a quarter of 
processor clock speed. Possibly around a half a micro second.


  Hope this helps.
  I'm posting this to the net in hopes that someone will say so if forbid won't
work like i think it will. - I could be wrong !  ;-)

     Don White
     Box 271177
     Concord CA.
     94527-1177
    
     donw@zehntel.UUCP
donw