[Coco] 6309 running in a Coco 1

[William Astle]

This is actually incorrect. 6309 native mode has nothing to do with 
clock speed. All it does is change the cycle counts for many 
instructions. It does not change the clock speed. In fact, the CPU 
itself has exactly zero control of the clock speed and the switch to 
native mode is a flag in a CPU register. You can perfectly happily run a 
coco 1 or 2 in 6309 native mode.

On 14-01-02 09:35 PM, Bill Pierce wrote:
> The problems I see with this is that you couldn't run in 6309 native mode on Coco 1&2. (Dragons too I think). Since the 6309 native mode runs at double clock speed, the Coco 1&2 would lose video just as it does when using the poke65495,0 & poke65497,0 in Basic. It's the very reason the double clock wasn't used by software on the 6809 back in the 80s. The VDG chip can not take the speedup. Possibly the SAM as well (???). On the Coco 1, the bitbanger port cannot use this mode as well. That's why there's no "Turbo mode" DW4 drivers for Coco 1. The Coco 1 had a flawed serial output and maxes at 38,400.