Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!columbia!rutgers!sri-spam!nike!ll-xn!adelie!axiom!linus!philabs!mcnc!ecsvax!ranger
From: ranger@ecsvax.UUCP (Rick N. Fincher)
Newsgroups: net.micro.apple
Subject: Re: stuff in general
Message-ID: <2138@ecsvax.UUCP>
Date: Thu, 16-Oct-86 08:46:07 EDT
Article-I.D.: ecsvax.2138
Posted: Thu Oct 16 08:46:07 1986
Date-Received: Sat, 18-Oct-86 23:08:28 EDT
References: <673@sphinx.UChicago.UUCP> <9800034@uiucuxa>
Organization: UNC Educational Computing Service
Lines: 33

> 
>     Written in responce 2 to this note.
> 
> Don't be silly. There are very important differences that you are
> ignoring when you talk about processor speed. Processor speed (when
> measured in Mhz) is relative!!! A 4 Mhz Z-80 (CP/M processor) is
> as fast as a 1 Mhz 6502. Those 3.5 Mhz Apple-turbocards speed up the
> Apple to about 1.5-2x faster than a PC....the speed at which a processor
> operates is only useful information when you are talking about the
> same family of microprocessors.
>  
>                (my text now)
> 
> I don't think a 6502 has a 4-1 advantage over a Z80. A 6502 has an 
> advantage because it does a full read in a cycle, unlike a Z80 
> which puts the address on the bus in one cycle and reads the data
> in the next. But that's only a two to one advantage. And all the 
> benchmarks I read seem to say about a 2x advantage, which is what you
> would think from my remarks.
> 
>    I run a 6502 at 2Mhz in my Commodo 128. It seem to be about 20% slower
> than an IBM PC.

The difference in the speed per clock cycle in the 6502 vs the 8088 is
or other processors is due to the hardwired architecture of the 6502
vs the microcoded architecture of the others.  Hardwiring eliminates
a decoding step in the processor but is more difficult to design and
debug, hence the more complex processors are usually microcoded.  I 
don't know if the Z-80 is a microcoded processor or not, so this may
not be the only factor in that case.

Rick Fincher
ranger@ecsvax