Path: utzoo!attcan!uunet!husc6!m2c!wpi!greyelf
From: greyelf@wpi.wpi.edu (Michael J Pender)
Newsgroups: comp.sys.apple
Subject: Re: 65c02's big brother
Message-ID: <7537@wpi.wpi.edu>
Date: 1 Feb 90 23:05:57 GMT
References: <202.apple.net@pro-dchamber>
Reply-To: greyelf@wpi.wpi.edu (Michael J Pender)
Organization: Worcester Polytechnic Institute, Worcester ,MA
Lines: 44

In article <202.apple.net@pro-dchamber> larryw@pro-dchamber.UUCP (Larry Walewski) writes:
>In-Reply-To: message from yu-r@ketch.cis.ohio-state.edu
>
>I own a Laser 128, and was wondering if changing to a 65c802 would speed
>this computer up?  Surely a $16 chip cannot do the same as a $100 Zip Chip? 
>Will changing to the 65c802 increase my 1Mhz speed?

In a nutshell, not really.  The real advantage lies in the ability to
port sections of 65816 code, and to use the new instructions in programs
you write yourself if you're a programmer.  

However if you're a programmer you can make MUCH faster code by making
use of these new instructions.  

For example, the following routine does a copy of a page of memory:
First store the source and destination addresses in the zero page
locations correspoding to source and dest, then...

	ldy #$00	2 cycles
loop    lda (source),y	5 cycles
        sta (dest),y	6 cycles
        iny		1 cycle
        bne loop	3/2 cycles

This will take roughly 16 + 255 * 15 = 3841 clock cycles.
On the 65c802, first set up the x and y registers to the
LSB within each page, then:

	mvp #>source,#>dest	7 clock cycles

Proper use of the features of this chip should provide a
drastic speed increase.  But it should not noticably 
affect the execution speed of porgrams written for the IIc/e.

Having a 65c802 does not allow one to run all IIgs software,
we don't have the GS toolbox nor sound, nor graphics.
In fact it doesn't really make the 65c02 capable of anything
it wasn't before.  But if used properly, it does it much
more elegantly (and damn quick...)

---
Michael J Pender Jr  Box 1942 c/o W.P.I.        ... (Mankind) has already 
greyelf@wpi.bitnet   100 Institute Rd.          used its last chance.
greyelf@wpi.wpi.edu  Worcester, Ma 01609               - Gen. MacArthur