[Coco] What happens if a slow 6809EP is used....

[jdaggett at gate.net]

On 19 Jan 2010 at 3:46, Mike Pepe wrote:

> In theory, yes, but I have never seen one that does... think of how often
> the "speedup poke" was used in the CoCo 1 & 2 days; it runs the CPU at
> double speed during ROM access. Very few (if any) folks ever reported they
> were unable to do so.

That is more to do with the VDG and SAM chips than with the MC6809E itself on the 
Coco1/2. The problem with switching the clock speeds when in the middle of an instruction 
really screws up the internal logic of the 6809. You need to insert at least one dead cycle and 
halt the processor when dynamically changing clock speeds. The speed up has to come after 
the last instruction cycle. With the 6809e you have an indicator when that happens with LIC 
output(last Instruction cycle).

james.