Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!decwrl!ucbvax!tut.cis.ohio-state.edu!osu-cis!killer!elg
From: elg@killer.Dallas.TX.US (Eric Green)
Newsgroups: comp.sys.cbm
Subject: Re: what is this chip(65C802)
Message-ID: <7789@killer.Dallas.TX.US>
Date: 8 Apr 89 05:07:44 GMT
References: <2310@maccs.McMaster.CA>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 39

in article <2310@maccs.McMaster.CA>, cs3b3aj@maccs.McMaster.CA (Stephen M. Dunn) says:
> In article <7734@killer.Dallas.TX.US> elg@killer.Dallas.TX.US (Eric Green) writes:
>>The 8080sux emulates the bus cycles of it's 8080 ancestory, which is
>>identical to the bus cycle of the Z-80 which we previously discussed.
> Just to make sure nobody gets the idea that the 8080 was based on the Z-80,
> it's the other way round.

Which is exactly what I said, in any event. We were previously talking
about the 4mhz Z-80 in the C-128, and someone wondered why it wasn't
twice as fast as the 2mhz 8502. A detailed description of its 4-cycle
bus cycle was posted, which is what I'm referring to above.

>>An 8080sux takes 4 clock cycles to read a byte from the bus. The 6502,
>>65c02, etc. take 1 clock cycle. Thus a 8 mhz 6502 would be the
>>equivalent of a 32mhz 8086-based machine. Considering that 80x6-based
> The problem with your argument is that you assume that everything on an
> 8086 takes four times as long as on a 6502.  I'd like to see you get

I can see where you got confused, but I was talking solely about the
memory speed requirements -- not CPU power. If you read my previous
notes about the Z-80, I noted that its ability to hold 16-bit
quantities in registers and a real 16-bit stack pointer made Z-80 "C"
and Pascal compilers produce much smaller and faster code than 6502
equivalent.  And of course the 8086 adds better memory addressing,
instructions for multiply and divide, and many other advantages (it
makes a dandy successor for the Z-80, though I doubt the 8086
designers were thinking of the Z-80 at the time).
    I have programmed extensively in 6502 assembly language, enough
such that I will never use a 6502 in any imbedded applications -- it's
not worth it, when you can buy 6809s cheap as sand. Using 6502s in a
systems application is, of course, absolutely brain-dead in today's
world where 68000s are as cheap as sand. But the C-64 was never
intended to be a system -- it was intended to be a cartridge-based
game machine.

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