[vcf-midatlantic] What limited the C64's CPU to ~ 1 MHz?

RETRO Innovations go4retro at go4retro.com
Thu Mar 23 14:16:48 EDT 2017

On 3/23/2017 12:36 PM, Dan Roganti wrote:
> I think this is why Bill Mensch left MOS and started WDC in '78,
I interviewed Bill long ago for an article, and I was not as aware of 
history then as now.  I wish I had been, as I would have loved to ask 
him how he managed to coerce Jack into paying for him to break off and 
start up WDC.  (he did fund at least part of WDC). THere must have been 
an agreement to not sue, or assignment of some specific part of the 6502 
in return for the money, is the only think I can figure.  I suppose 
someone should try to get Bill to come to a VCF (VCF-W) and give the 
complete picture.  Given how tight Jack was with money, and the amount 
of money that I seem to recall Bill got, there had to be something 
massive to leverage.
> and made further improvements in speed and instructions to the 6502​ 
> and then later the 65816
Somewhere there is the store about the 65C816 and the Apple II gs.  Ah, 


The 65c816's design was not without it's problems.  Bill Mensch
"improved" the bus interface on the 65c816 (over that used by the
6502).  Unfortunately, the Apple's disk drive controller relied on some
of the old kludges in the 6502 chip.  With those problems removed, the
65c802 and 65c816 chips worked fine on an Apple computer, but the
disk drives didn't work.  Of course Apple immediately began laminting
about the stupidity of the designers at WDC and WDC's designers
immediately began complaining about the stupidity of Apple's design.  In
the long run, money won out.  If WDC wanted Apple to use the '816,  WDC
would have to redesign the chip.  They did.

I always wondered just what the "improvement" was that had to be 
discarded. (read before write?)


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