On Thu, 24 Sep 1998 [EMAIL PROTECTED] wrote:
> > 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...
That's interesting! I had saw the hardware of a Panasonic MSX2+, so I
couldn't say nothing about Turbo-R's. But for compatibility reasons, I
think that the implementation probably was done in hardware.
> 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.
Are you sure that there's no way to enable the PAUSE key in R800 mode?
Supposing hardware implementation, it's possible that there's a bit in a
certain port that enables or disables the PAUSE key in R800 mode.
The big problem is the lack of information about the chip S1990. AFAIK,
the circuit designed for PAUSE key in MSX2+ was implemented inside the
S1990 in Turbo-R. So, for a chip designer, it's very easy to create an
extra port to control the PAUSE key.
Greetings from Brazil!
--------------------------------------------------------------
Marco Antonio Simon Dal Poz http://www.lsi.usp.br/~mdalpoz
[EMAIL PROTECTED] "The measure of success is the knowledge"
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