On Tue, 21 Sep 1999, Giovanni R. Nunes wrote:
> >>is it posible to disable the pause key on the turbo r in basic?
> > The pause key can only be disabled if the program runs in R800 mode.
>
> If you're patching the BIOS copied in RAM you can use it to execute
> programs in R800 DRAM and in Z80 DRAM, this mode exist but isn't hard
> doccumented, try to test the program 2MSX made by Nyyrikki to see the
> use of it.
Even in Z80 DRAM mode, the pause key cannot be disabled.
The reason is that in Z80 mode, the pause key generates a hardware pause,
that actually freezes the CPU.
If you for example use a custom page 0 instead of the BIOS, the pause key
still works in Z80 mode.
In R800 mode, the pause key is checked in software (interrupt routine in
the BIOS) and can easily be disabled. The Z80 and the R800 in the turbo R
are two different CPUs...
I was just wondering... If pause is pressed during disk access in Z80 mode,
problems could arise. What happens?
- disk I/O is always done in R800 mode (not true, as far as I know)
- the pause key is disabled using some yet unknown mechanism
- pressing pause messes things up, but the disk I/O routine can recover
- something else?
Bye,
Maarten
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