At 01:06 AM 3/30/99 +0100, Tony wrote:
> Actually, it might be as correct to say that 8088 signal names are more or
> less like "all the other" microcomputers in the non-Motorola camp. with
the
8085 and z-80,
it became obvious that the large number of strange signals
generated by the 8080 didn't even help the Intel folks with the task of
interfacing the processor to memory and peripheral devices. The simple
One of the problems with the S100 bus is that it is _very_ dependant on
the 8080 signals. Even using a Z80 is a bit of work - things like PINTE
(which indicates if interrupts are enabled) and SSTACK (address lines
contain the value of the stack pointer) don't exist as external signals
on the Z80.
Of course if you wire your own Z-80, you can ignore most of the weird
signals if you are using static ram. Just use a memory write signal for
writes, and another to gate read data onto the buss.
Actually, I prefer the Motorola / PDP11 idea of having
memory and I/O in
the same address space. It means you can use the same instructions and
addressing modes to access either.
There is nothing in the Z-80, etc. to prevent you from using memory mapped
I/O.
Of course if some peripheral hardware uses I/O instruction decoding, them
you use those instructions for its interface.
-Dave