Re: C64 2 Mhz Hack

From: Marko Mäkelä (
Date: 2001-02-23 14:31:05

On Fri, 23 Feb 2001, Professor Dredd wrote:

> My brother just sent my documents detailing a hack to
> run the C64 at 2 Mhz. It looks really simple, but my
> electronics skills are far to rusty to implement it. 

Then I guess it can't be the same hack that was published in the 64'er
Magazin 2/94 or 3/94.  That hack used lots of logic glue to implement the
I/O port at locations 0 and 1, and to construct a clock signal that
generated two clock pulses for the CPU during the CPU bus cycle halves.  
In other words, it ran the 6502 at 4 MHz for 2 cycles and at 0 MHz while
the video chip was doing its transparent DMA.  In this way, the computer
ran at 2 MHz with the screen turned on.

Another possibility is to use a C128 video chip to produce the exact
equivalent of the C128 "2 MHz mode" on a C64.


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