MITS 2SIO serial chip?

From: Ethan Dicks <>
Date: Thu Dec 20 00:11:40 2001

--- Greg Ewing <> wrote:
> Ben Franchuk <>:
> > what is the faster CPU -- A 6502 or Z80 style processor
> Back when I used to spend long blissful evenings hand-assembling Z80
> programs [1] I got the impression that Z80 code was more compact than
> 6502 code, being able to manipulate 16-bit values with single
> instructions in many cases.

If you had enough zero-page locations left over for your app after
the OS was done with them, typically, 6502 code could be quite
compact. Embedded stuff (like C= disk drives) was a little easier
to write in that regard because you had the entire page to do as
you wished. Infocom did just about the same with their Z-machines
for the C-64 (which is why you had to power-down when you were done
playing - the zero page was full of Z-machine values and the interpreter
did not save them anywhere to restore them before exiting).

I've always felt (personal impression) that a 4Mhz Z-80 could outperform
a 1Mhz 6502, but I never got the chance to do any comparisons when faster
chips (of both kinds) came out. I'd already moved on to 68000s. Because
I like the 6502, I would hope that a 4Mhz 6502 could do a little better
than a 4Mhz Z-80, but I'm not certain. The 6502 does have a one-cycle
pipeline internally, and it does interleave CPU and memory operations
efficiently (phi2 clock and what not), but I don't know the Z-80 to
the same depth and can't make a fair comparison myself.


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Received on Thu Dec 20 2001 - 00:11:40 GMT

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