After finding these instructions I decided to
try to construct such a device. After ~$20 at Rat Shack and a couple hours
of work I had the above. However, since I run RC5 all the time, watching
CPU usage is pretty boring. Stealing some code from Rob Malda of Slashdot fame I hacked out a simple
daemon that would make the geektoy act like external modem lights.
Now in version 0.5 the code is slightly cleaner and support up to four
input lines to be used as switches. My model, which only has one switch
currently (used for making and breaking ppp connections) is seen above.
The code is currently set to watch input lines 10, 12, 13 and 14. If you
wanted you could add a fifth switch on line 11 (seen as the most
significant bit returned from port_in(port+1)) but it is inverted. You
could also add four more LEDs on lines 17, 16, 14 and 1, though I suggest
leaving line 1 open for power, since certain parallel ports require a
pullup source to register input.
Here is a nice tarball of all the code, the docs and two utility programs I
found amusing: geektoy-0.5.tar.gz
I have found geektoys make good presents. The latest represents the
state-of-the-art in geektoy design, though sadly I have no pictures. Yet.