Re: Parallel Card

["mdj" <mdj.mdj@gmail.com>]

Hi,

IMHO the best parallel card for the Apple II is the ProFILE interface
card, as they're bidirectional, but these are almost impossible to
find.

If you simply want to drive/test 16 LED's, you can do this easily, and
extremely cheaply from the game connector, and save yourself some
money, and 2 slots.

Just grab two 74LS164's from the local electronics shop. This component
is an 8-bit shift register. In essence, you connect the reset, clock
and input pins of a shift register to the annunciators on the game
port. Each of the 8 outputs is then connected to an LED.

A very simple program can then be written to 'shift' 8 levels into the
register, allowing you to turn on and off the LED's.

To add another 8 LED's, simply 'cascade' another shift register by
connecting its clock and reset in parallel, and wiring it's input in
parallel to the 8th, or H output of the first register.

Using this technique, you can control a *lot* of LED's very easily.
It's much cheaper than a parallel card and a lot more fun :-)

Matt