Re: Apple 2e - building a simple expansion card and calling it from BASIC (or assembly)?

[scott@alfter.DIESPAMMERSDIE.us (Scott Alfter)]

In article <1193087468.610280.68130@q5g2000prf.googlegroups.com>,
 <mad.scientist.jr@gmail.com> wrote:
>Has anyone built their own Apple 2 expansion card and programmed it to
>do something?
>
>If it wouldn't be ridiculously hard, I would like to try etching a
>circuit board to plug into one of the expansion slots on my 2e. The
>board would contain a single relay, which could be opened or closed
>from BASIC code (or if it is not possible from BASIC, from 6502
>assembly).

To switch a relay on and off, I'd use an annunciator line from the joystick
port.  A card in an expansion slot will need at least a buffer and a latch;
at the joystick port, all you'll need is an NPN transistor, a diode, and a
resistor or two.  You could use an expansion slot for what you want to do,
but to me it sounds a bit like swatting a fly with a sledgehammer.

In either case, some PEEKs and POKEs are all you'd need to control it from
BASIC.

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