[sdiy] learning from early drum machines?

[Paul Maddox]

>> Or, instead of 16 x 4 switches, 16 x 4 LEDs and 16 + 4 switches
>> (one for each row and one for each column). Pressing a row button
>> while a column button is pressed (or vice versa) toggles the
>> intersection.

Sounds like an SDS-6 to me
http://www.simmons.synth.net/sds6/

only that had 8 rows of 32 LEDs.

Paul