The 2N2/256-BSCP [was: Homebrew Drum Computer]

You'll kindly observe that I had the good taste not to also mention Shockley diodes, which, to the best of my knowledge, are really unobtainium. American Microsemiconductor still offers a selection of tunnel (Esaki) diodes, for as cheap as $9 the each. http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html I suspect a clue to the high prices is the "JAN" labeling on some of the parts (i.e. military and aerospace application). I have a copy of the GE tunnel diode handbook around here somewhere (as well as about a dozen or so NOS diodes in my hellbox) that shows all manner of logic circuits constructed with the little beasts. I've never even breadboarded any of them, but the power requirements look very modest. OTOH, I've never seen a book detailing logic circuits with Shockley diodes, though I imagine it's certainly possible. Cheers, Chuck