Re: C64 2 Mhz Hack

From: Professor Dredd (profdredd_at_yahoo.com)
Date: 2001-02-23 16:57:43

Hiya Marko!
--- Marko_Mäkelä <msmakela@cc.hut.fi> wrote:
> Then I guess it can't be the same hack that was
> published in the 64'er

Yes, actually I think we're talking about the same
hack. I've never seen an issue of 64'er though  :(

> 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.  

Well, the schematics didn't LOOK complex to me. But I
am not an electronics professional.

> 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.

Wow, I didn't know you could do that!

> 	Marko
> 
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