RE: [cc65] Machines with switchable clock

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From: Steve Nicklin (steve.nicklin_at_hp.com)
Date: 2003-02-20 15:24:41 

The Atari 8 bit with a

poke 559,0

will speed the processor up by 30% by switching the screen off


-----Original Message-----
From: Tim Schürmann [mailto:tischuer_at_web.de]
Sent: 20 February 2003 14:48
To: cc65_at_musoftware.de
Subject: Re: [cc65] Machines with switchable clock


Hi!

Marko Mäkelä schrieb:

> On Sat, Feb 15, 2003 at 11:06:03PM +0100, Groepaz wrote:
> > On Saturday 15 February 2003 20:39, Ullrich von Bassewitz wrote:
> > > Just out of curiosity: Apart from the C128 (and C64 mode on a C128),
are
> > > there other 6502 machines that have a user switchable CPU clock?
> >
> > uhmz... didnt the plus4 have some sort of 2mhz mode? *scratcheshead*
>
> Yes, or 1.6 MHz mode to be exact.  The CPU is automatically slowed down
> during video access, so you can't get the same sort of garbled screen as
> with the C128.

The Sinclair ZX80 and ZX81 (with a Z80 CPU) are working similar: with video
turned off, the cpu runs faster (because the CPU has to do all the
graphics).
So, the ZX80 has two modes: fast and slow.

Bye,

Tim

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