Re: VIC-registers

From: Marko Mäkelä (
Date: 1998-03-02 13:23:36

> IFF the VIC-II does _not_ return _anything_, i.e. does not drive the bus
> this _might_ work. If the VIC drives the bus high, you may fry your VIC
> when the other chip drives the bus low!

The VIC-II does drive the data bus to high state, but keep in mind that it
is an NMOS device.  You can always let the bus perform a wired-AND between
NMOS outputs.  If the situation was like you described, then even moving
the joystick might fry the CIA (remember, one of the joystick ports is
normally an output, outputting high state).

With CMOS devices this is a completely different issue.


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