Re: AltairZ80 simulator updated

On Wed, 30 Jul 2008 14:25:00 +0200, Axel_Berger@xxxxxxxxx (Axel
Berger) wrote:

*Barry Watzman* wrote on Tue, 08-07-29 02:55:
memory mapped I/O

Please correct me, but as far as I know neither the 8080 nor the 8086
nor any of their derivatives use memory mapped I/O. In fact this is
what made the IBM-AT emulator for the Atari using little more that a
bare 80286 possible -- all I/O were redirected to native 68000
subroutines and all memory accesses done directly.

Generally they do not. But, there is NOTHING to prevent you from
doing so and I can state that one system the NS* Horizon uses memory
mapped IO to do the FDC.

There are a lot of good reasons to do memeory mapped IO on
8080/8085/z80 (and others) in that you ahve greater address space
and logical operations on ports are doable plus word (16bit) transfers
in a single instruction even with 8080!

Allison
.

Relevant Pages

  • Re: AltairZ80 simulator updated
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