[Coco] Video sync issue... (crosspost)

[Arthur Flexser]

As I understood what he was asking, he was inquiring how to sync to the vertical
video pulse, which in the CoCo generates an IRQ (assuming proper enabling) that
the SYNC instruction will wait for, in order to avoid flicker in a game he was
programming.  The instruction is used for this purpose in Basic's PALETTE
command, for example, though the same can also be accomplished by looping and
checking the interrupt flag bit without halting the processor.

Art


On Thu, 11 Nov 2004, Mark McDougall wrote:

> Arthur Flexser wrote:
> 
> > The SYNC instruction suggests itself.....
> 
> No. This instruction will cause the processor to stop processing 
> instructions and wait for an interrupt. It has nothing to do with video 
> signals - nor could it as a CPU has no inherent knowledge of the surrounding 
> hardware.
> 
> Regards,
> 
> -- 
> |              Mark McDougall                | "Electrical Engineers do it
> | <http://members.optushome.com.au/msmcdoug> |   with less resistance!"
> 
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