Re: C64 Tower
=============

Subject:      Re: C64 Tower
From:         Nate Dannenberg <natedac@onyx.southwind.net>
Date:         1998/03/08


> > the AC sine was as its timing constant?  At least this is what I was told
> > often and repeatedly when I tried to make a portable 64 system run on a
> > battery pack.
> 
> The 9VAC has nothing to do with timing.

Not exactly.  The 9VAC is used to drive the CIA's "TOD" clocks.  It uses
the 60Hz pulse as a simple timing signal.

In PAL countries this is a 50HZ signal, which is why the CIA's have
PAL/NTSC settings in them. 

The 64 uses a 14.31818 MHz XTAL crystal (some 17MHz in PAL) as the timing
base for everything, from which the VIC-II generates the "Dot"  clock (the
pixel timer), the 3.58MHz (~4MHz PAL) color clock used for the color
signal, and the 1.022 MHz system clock (0.98 Mhz in PAL).




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 natedac(at)southwind(dot)net //\_/ http://www2.southwind.net/~natedac

    
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