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

[mad.scientist.jr@gmail.com]

Thanks for your reply...

> 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.

If all you wanted to do was turn on one relay maybe, but what about 4
or 8 or more? Some things I'm looking to do
* set the value of 1 or more potentiometer (control resistance from
the computer)
* read the value of 1 or more potentiometer (into an 8-bit number =
ok)
* read whether a switch (actually 8 or more switches) is closed or
open, and be able to tell if several are pressed at the same time
* open/close 8 or more relays (or an electronic switch such as a
transistor which is faster)
* control SPDP switch(es)

Someone recommended some books ("Apple interfacing" was one) which I
have to locate. The site vernier.com seems to have some related
projects as well.

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

Well that part is promising... Any good examples?




On Oct 23, 1:46 pm, sc...@alfter.DIESPAMMERSDIE.us (Scott Alfter)
wrote:
> In article <1193087468.610280.68...@q5g2000prf.googlegroups.com>,
>
>  <mad.scientist...@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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