stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

From: Pete Turnbull <pete_at_dunnington.u-net.com>
Date: Sun Apr 11 16:26:15 1999

On Apr 11, 14:37, Allison J Parent wrote:

> Yes, the 6502 overlaps the instuction fetch and execute (mini pipeline).
> The z80 is more classic multi-state machine. In the end the two parts
are
> roughly the same speed for their generation. IE: a 4mhz z80 does basic
> operations in 1uS and 6502 at 2mhz is about the same.

That's about my estimation, Richard's example not withstanding.

> the difference is
> any is when complex indexing or other tassks are discussed where the z80
> has a better instuction set (though slower...more states) the 6502 uses
> more small instructions(fast but many).

I'm not sure I'd agree, when it comes to indexing. I think the 6502
indexing is more useful in typical cases, and the instruction set is much
"cleaner" in some ways. However...

> In the end they do the same task just different.

Exactly. I was brought up on the Z80, or at least that's what my earliest
assembly language experience was on, but I learned how to use a 6502 pretty
well. Just a different design philosophy.

> That supports the only logical conclusion... clock speeds dont count.


-- 
Pete						Peter Turnbull
						Dept. of Computer Science
						University of York
Received on Sun Apr 11 1999 - 16:26:15 BST

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