[Coco] Arduino as a Mouse/Keyboard interface?

[Darren A]

On Mon, Jul 2, 2012 at 6:35 PM, Steve Bjork wrote:
>
> Another way is to halt the 6809 when the column output lines changes.  Just
> use compare logic to halt the 6809 and tell the microcontroler to update the
> data on the 8 bits of the row lines feeding into the other PIA.

That would likely create problems when executing an instruction
sequence such as:

STB  PIA_COL
LDA  PIA_ROW

The HALT signal would not be asserted until after E goes high in the
last cycle of the STB instruction.  I'm pretty sure that means the CPU
would not actually halt until after execution of the LDA instruction
(doesn't meet the required setup time).

Darren