[Coco] Questions about the Coco3 GIME Timer

[Gene Heskett]

On Tuesday 13 February 2007, John Kowalski wrote:
>At 10:27 AM 13/02/2007 -0500, Robert Gault wrote:
>>  What I have not determined is when the new 12-bit value becomes
>>effective if only $FF95 is changed. Is the change immediate or does it
>>take place on the next count down.
>
>>From what I've seen, only writes to $ff94 cause the timer to immediately
>reload with the $ff94/$ff95 values.
>When you write to $ff95, the timer will only reload with the new values
> when it counts down to zero and retriggers.

Do you recall the tick resolution of this timer, John?  If its not in 16ms 
increments, but finer, as in hsync or even Eclocks, this would be a great 
way for George to get some higher speeds out of his coco while driving 
the steppers.  But of course there is only one timer, and there are at 
least 3 axis's to independently control.  So it looks as if that's ruled 
out.  Darn.

>>  The answers to these questions become important if the timer is used
>>to measure a single interval. It will be important to know whether the
>>timer can be loaded with a 16-bit register or whether two 8-bit loads
>>are required, $FF95 then $FF94.
>
>$ff95 then $ff94, otherwise the timer will use $ff94 + whatever was
>previously in $ff95 for it's first countdown before reloading with the
>correct value.
>
>                                         John Kowalski (Sock Master)
>                                        
> http://www.axess.com/twilight/sock/



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