[Coco] [Color Computer] Re: POKE 65495,0

[Darren A.]

>From: jdaggett at gate.net
>
>On 3 Feb 2007 at 18:58, James Diffendaffer wrote:
>
> > James, if your read back through the tread you'll find we were talking
> > about running the CoCo 1/2 in SAM high speed mode with the RAM refresh
> > disabled.
> >
>*************
>First off I don't believe that you can disable the refresh counter on the 
>SAM chip.
>
>--

The datasheet for the SAM says that both the RAM refresh and VDG access to 
the RAM are disabled when running in FAST mode. This is different than the 
Address Dependent mode which doubles the CPU clocks only when the SAM is in 
Map Type 0 and while the CPU is not accessing RAM.

When people talk about the double-speed poke for the CoCo 1/2, they are 
usually referring to Address Dependent mode, since FAST mode results in loss 
of the video display. There is no need to add any kind of refresh during IRQ 
for Address Dependent mode.

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