> On Mon, 21 Sep 1998, Maarten ter Huurne wrote:
>
> > At 09:14 PM 9/21/98 +0300, you wrote:
> >
> > >> Just try to catch the turbo R PAUSE button in Z80 ROM mode. If you
> succeed,
> > >> I'll give you a big applause. I never managed to disable it, and I
> really
> > >> wanted to, because pressing PAUSE gave away all our line interrupt
> tricks.
> > >
> > >Select RAM to addresses 0-#3FFF and put RETI command to #38. I bet you
> > >don't have probblems after that. (Atleast, if you don't try to use BIOS
> > >commands.)
> >
> > We (Mayhem) used a custom BIOS in RAM, but still the PAUSE key worked!
>
> Of course the PAUSE key worked!!! This key is hardware implemented! I saw
> it in a Panasonic FSA1WSX (MSX2+) and the PAUSE key access a circuit that
> controls the clock flow. But this demands a special refresh circuit, which
> I couldn't found, but I know this has to exist.
The thing is that this problem we (Mayhem) encountered is a little more
complicated. As Maarten wrote we put RAM on all pages (0000h-FFFFh) with our
own BIOS and interrupt service routine, so in fact we have complete control
over the machine. The complication lies within the following: in R800 mode the
PAUSE key does NOT work, but in Z80 mode the PAUSE key DOES work. So while the
R800 mode hints at a software implementation of the PAUSE key, the Z80 mode on
the contrary hints at a hardware implementation...
So disabling the PAUSE key can be achieved by simply activating the R800
mode, but sometimes you do not want this and are forced to use the Z80 mode
(for instance due to the slowed down VDP access in R800 mode). To our dismay we
weren't able to come up with a solution for it - I'll admit, it is bit of
personal frustration. Anyway, this is why you will get an applause if you do
succeed in disabling the PAUSE key in Z80 mode on a turboR.
Bye, /\/\ark
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