> > ?? Z80 has 256 I/O addresses, not 64k! It only uses the lower byte of
the
> > address
> > lines to address I/O ports. I don't know about Z180, but my guess
> > is that that processor uses 16-bits I/O adressing space (equals 64k)
>
> I heard that Z80 actually publishes BC on the bus when doing "OUT (C),r",
> but that the MSX only uses the lower 8 bits. I'm not sure though.
You are right.
And it publishes the contents of A on the upper 8 bits of the address bus
when doing an IN A,(n) or OUT (n),A.
Hence, you can IN a value from I/O port 1099 by doing
LD A,#10
IN A,(#99)
ADVRAM makes use of this. RicBit wrote something about that...
(I don't know about any other devices).
~Grauw
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