[Coco] Clock "Timing".

[Arthur Flexser]

Actually, the TIMER function's main source of inaccuracy is that reading
the keyboard, which occurs between Basic statements in checking for the
break key, causes an occasional interrupt to be skipped.  (That's due to
the presence of a couple of LDA $FF02 instructions within the keyboard
polling routine that cause the IRQ flag to be cleared.)  If you knock out
the break key check, TIMER's accuracy improves considerably.

Art

On Tue, Apr 4, 2017 at 3:35 PM, Bill Gunshannon <bill.gunshannon at hotmail.com
> wrote:

>
> ________________________________________
> From: Coco [coco-bounces at maltedmedia.com] on behalf of Dave Philipsen [
> dave at davebiz.com]
> Sent: Tuesday, April 4, 2017 3:07 PM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] Clock "Timing".
>
> Art brought up the use of the TIMER function which I had completely
> forgotten.  Sounds like your best bet.  You may still have to test it
> and trim it to increase accuracy.
>
> Dave
>
> __________________________________
>
> Be aware.  It probably stops counting during cassette and disk I/O.
>
> bill
>
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