Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!oliveb!amiga!cbmvax!dan
From: dan@cbmvax.UUCP (Dan Baker CATS)
Newsgroups: comp.sys.amiga.tech
Subject: Re: CIA Timer Example
Message-ID: <5594@cbmvax.UUCP>
Date: 29 Dec 88 17:07:33 GMT
References: <1439@percival.UUCP> <5587@cbmvax.UUCP> <38@sdcc10.ucsd.EDU>
Reply-To: dan@cbmvax.UUCP (Dan Baker CATS)
Distribution: na
Organization: Commodore Technology, West Chester, PA
Lines: 28

In article <38@sdcc10.ucsd.EDU> cs161agc@sdcc10.ucsd.edu.UUCP 
(John Schultz) writes:
>
> [Long CIA timer program deleted....]
>
>  What's the scoop?  What is the bottom line on these timers? Am I
>reading the docs wrong, or is the documentation inaccurate?  
>  Timer B on ciaa *should* be available. 

CIA-A timer B is reserved for system use.  CIA-B timer B is available for 
applications.  The Hardware Manual is WRONG on this point.  Timers are
allocated as follows:                 -----

  CIA A  timer A  Used for keyboard handshake.
         timer B  Used for uSec timer.device.
         TOD      Used for 60 Hz timer.device.

  CIA B  timer A  Commodore 8-bit serial bus communication.  
         timer B  Not used.
         TOD      Used for graphics.library beam counter.

Use CIA-B timer B for your applications.  CIA-B timer A could also be used
although this is reserved for a "1541-style" interface for products like the
64-Emulator.  For more on this see Bob Burns' article in the Jan/Feb '89
issue of Amiga Mail coming soon.  Also see Paul Higginbottom's example
CIA timer porgram in the Sept/Oct '88 issue of Amiga Mail.
-- 
 Dan Baker, CATS