RE: joystick ports

Yeah, think of it in terms of a collection of NMOS transistors. A bunch of
mushy things all pushing on each other in a way that eventually makes a
voltage into either high enough to be called a 1 or low enough to be called
a 0.


> (Personally, I find this little device a pretty brilliant one,
> with/despite its simplicity, especially whenever I make an attempt to
> build some of its functionality from TTLs ;-). Probably not much more
> complicated in itself than a usual TTL bidirectional bus driver, yet
> very efficient to use in practice. The only thing I'm missing is a
> reset input (which probably wouldn't fit the DIP20 package)).

Same here. Whenever I try to think of a replacement using only TTLs, it
becomes a surprisingly complicated circuit if I want to emulate all
funktionality from the datasheet. If you only want to replace the 6529 used
for the keyboard in the 264 series, you _might_ be able to get away with a
374 (pinout adjusted).

Luckily, the 6529 does seem to be pretty stable, so far I didn't have a
broken one.

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