Maarten ter Huurne wrote:
>
> On Thu, 22 Jun 2000, Leonard Silva de Oliveira wrote:
>
> > Some time ago I noticed that Turbo-R machines does that with all MSX
> > system
> > reserved I/O port ... Then if you try to read any I/O port that has a
> > internal
> > pehiperal installed the S1990 chip engine will block output from the
> > cartridge.
> > I guess it's made this way to avoid "totem pole" (bit conflicts) of
> > S1990
> > internal buffer with the internal machine devices such as PPI, VDP,
> > PSG , Mapper, etc ....
>
> I don't think this is true. For example, Padial's PC keyboard interface is
> inserted in an external slot and acts like a partial PPI. And ofcourse it
> supports all keys, not just the ones in columns 0 to 4 (lower 5 bits).
>
> Bye,
> Maarten
Funny ... I remember that some time ago one of the Spanish users told
about
this interface. He stated that the interface was supposed to be
installed
internally on Turbo-R computers because of technical problems ... I
guess
the I/O mask inposed by S1990 is the cause of that. I wonder why you
guys
don't turn on your T-R computers and try out what I'm saying instead of
saying I'm wrong ... If someone could prove that I'm wrong then I'll
shut-up
(I'm not saying that it's impossible to read reseved I/O thuru external
slots
in all existing MSXes ...
I'm saying it's impossible to read reserved I/O thuru external slots in
original
Turbo-R computers.Putting modified machines in the list isn't fair ...)
;)
But seriously... No matter how many times you try ... You will be every
time
reading the registers of the internal pehiperal in that port ...
Cya MSXers ...
(I guess someday you guys will belive me ...) ;)
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