[Coco] Cartridge memory - mapping in and out

Roger Taylor operator at coco3.com
Mon Oct 29 23:08:42 EDT 2007

At 04:48 PM 10/29/2007, you wrote:
>On Mon, 29 Oct 2007, Roger Taylor wrote:
> >
> > (On a CoCo 3) I think doing a POKE 65502,x from BASIC is a no-no
> > because it switches out the patched ROMs (which are in RAM) and
> > switches in the underlying actual ROMs, and performing any commands
> > now could crash the system.
> > That's what the EXEC $E010 does,... very quickly by machine language
> > - sets up the GIME and RAM/ROM switch to prepare to run the cartridge
> > ROM without letting the user fiddle around at the prompt or perform
> > any other functions.
>This is not actually true, Roger.  The CoCo 3 patches were carefully 
>designed to
>avoid such a crash, for compatibility with existing programs.  The only thing
>is, you can't do the ROM poke from the 40/80 column screen, since the screen
>drivers for that are in the Super Extended Basic RAM that will be 
>switched out.
>(I don't recall whether you can still type blind if you do the poke 
>from a 40/80
>column screen, or if the CoCo just crashes in that case.)

Let me rephrase... performing "some" commands could crash the system.

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