Re: AB180-20 Z80,Z180 compatible microprocessor

[Eric . Boon]

Grauw wrote:

>> * 1MB memory, 64k I/O
>
> Same on Z180. The Z80 already had 64k I/O, when using OUT (C),r or IN
A,(n).

?? 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)

> So that's nothing new either. And it's certainly not useful, because to
> remain compatible with the architecture of the MSX, we can only use 265
of
> the existing 64k I/O ports.

YM: 256, not 265, i guess ;-)

     Eric



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