[Coco] POKE 65495,0

[Phill Harvey-Smith]

Quoting Robert Gault <robert.gault at worldnet.att.net>:

> The article claims, "Also if you were using the upper 32k of ram, the
> double speed poke would wipe the memory." which is wrong. I ran some of
> my ml programs using the $FFD9 switch which ran both RAM and ROM at
> 2MHz. Video was lost during this period but immediately returned to
> normal when the clock rate was slowed. So RAM was not wiped.

As noted in another post, doing this turns off the memory refresh, if  
you get memory corruption after this will largely depend on what type  
of RAM you have in there, from experience the 4116/4164 used in the  
CoCo 1/Dragon 32/64, will decay fairly quickly, however the 4416/4464  
chips used in some of the CoCo 2s, will oftern survive even a power  
off for several seconds, eg type a simple basic program :-

10 PRINT "PHILL WAS HERE ! ";
20 GOTO 10

Run it to make sure it runs, then hit break, power of for a couple of  
seconds, power back on and the machine will soft reset, type run and  
it will run :)
(my record so far is about 5-6 seconds :) ).

This can be a real pain, when the machine crashes as it can sometimes  
take up to 30 seconds for $71, to become corrupt so the machine does a  
hard reset :(

Oddly, though the CoCo 3 also contains 4464s, it doesn't seem to  
suffer this problem.

Cheers.

Phill.


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