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

Dan Roganti ragooman at gmail.com
Thu Mar 23 13:36:17 EDT 2017

On Thu, Mar 23, 2017 at 1:14 PM, RETRO Innovations via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

> In my opinion, the 64 ran at 1MHz, because Jack did not have interest in
> investments needed to make the chip faster.  He wanted it cheap and
> plentiful.
> In some respects, this aligned with the original MOS goal.  CPUs for the
> masses, cheap.  I am sure the HW guys would have loved to do more R&D, but
> MOS' tech was "good enough" to support the company, and that's what Jack
> focused on.
> I believe there are -2 and -3 MOS NMOS units and had been for some time,
> but Jack didn't need fast, he needed fast enough and that was it.  Running
> at 2MHz would have required static RAM or faster DRAM, so 1MHz (essentially
> 2MHz due to the CPU/GPU bus sharing) was fast enough.
> JIm

I think this is why Bill Mensch left MOS and started WDC in '78,
and made further improvements in speed and instructions to the 6502​ and
then later the 65816

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