From: Marko Mäkelä (marko.makela_at_hut.fi)
Date: 2004-01-19 08:46:31
On Mon, Jan 19, 2004 at 01:08:21AM +0200, Gianmario.Scotti@nokia.com wrote:
> In Europe, however, it's 50Hz, and it's this signal that, if I understand
> correctly, is used to generate some video timings in some (all?) commodores.
Mario, your other explanations make sense, but this one is not true. The
video timing is tied together with the bus clock frequency. On the Commodore
64 and 128, the 50 Hz or 60 Hz signal is fed to the CIA Time of Day clock
input. That clock is not used by the KERNAL, but some applications
(most notably GEOS) use them as a real time clock.
For instance, the old-style VIC-20 with the two-pin AC power connector runs
with DC voltage (1 to 1.5 amps from a 12-volt car battery charger). It has
a rectifier bridge directly after the connector.
Marko
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