Learning the Art of Electronics - keypad

[David1]

@bd139. Do you know what's different about the old and new keypads?

[David1]

@rstofer If you Google "student manual for the art of electronics" someone has pirated the whole thing...

[bd139]

Look on libgen.io

The 2nd edition keypad (sorry wasn't 1st) is used to load SRAM up for a 68k CPU so had some stuff in it to support that.

[rstofer]

I'm pretty sure the keypads are identical.  Signals not used in the latest edition simply won't be used.  I suppose the logic could be eliminated for unused signals but that might be unwise.

I have never heard of the MC14490 Hex Debounce Circuit - surprisingly, they are in stock at DigiKey.  Very handy chip!

[David1]

Update on 20 June 2018:

The author, Thomas Hayes, has been away on vacation but has got in touch to say he will put up-to-date details of the keypad on the Learning the Art of Electronics website. It is different from the one in the old Student Manual as he has re-designed it with a microcontroller in place of the many IC's of the older version, to do keypad scanning, switch de-bouncing and display.