R. Martin wrote:

> I didn't totaly follow the argument at the time it was of the nature
> of a law of physics or mathemetics (or death and taxes). It was
> calculated that the memory systems would lock up about once every
> ten years. Nobody confirmed this experimentaly.

Greg Brault wrote:

> I wanted the design to use the less space possible, less construction
> needed, etc.. So using 1 pic compared with 10 scrs, or 1 pic compared
> with a D flip flop with a 10 input OR gate... well, i chose the pic :)


Greg,

One 22V10 PAL might just do everything for you.  My point was, a PIC
can't look at all the inputs at once.

Why do you need the decoder and encoder?  Just use port B and half of
port A of a PIC16C54 or something.  Connect LED's through current
limiting resistors from power to PIC I/O pins.  Connect momentary N/O
switches to ground the I/O pins and LED cathodes when pressed.

Your program sets all 10 pins as inputs then continuously scans them
looking for a low input.  You'd probably need 100k pull-ups on the I/O
pins.

When a switch is pressed, it lights the corresponding LED through the
switch.  The PIC sees that input is low and then jumps to a routine to
make that input an output and then make it low until reset.

Don