morphed to TTL part number history, was: IBM PLAYING CARDS

I was talking with a fellow who worked for a local pipe organ builder (now retired) about their needs for logic in the adjustable combination actions of their instruments. For non-organists, this basically is the mechanism that allows a player to set combination of stops so that they are actuated by depressing a button or a toe stud. Basically a memory with a bit of control logic driving some actuators connected to the drawknobs. Given that we still have instruments around that were built in the 13th century, I asked the guy what they did about making sure that there was a 100-200 year supply of replacement ICs. IIRC, they used mostly 74LS TTL and some CMOS and a bunch of power Darlingtons,etc. (a bit more about that later). He replied that they make up a care kit with 2 of everything and place it safely away inside the console. I opined that this hardly seemed like enough. He said that the function was simple enough that the kit was mostly to get one past minor repairs; they expected that periodic redesigns would be routlinely undertaken with the appropriate modern logic. BTW, the power components are mostly for visual effect. He said that if a tracker action instrument (which is what they made) was being installed, organists demanded drawknobs that moved and not simple buttons, which would be far easier to accomodate. Go figure. A couple of years ago, I was reading about the lock controls on the Panama Canal and, at least until a few years ago, they're still original equipment installed in the 1910's, all that nice brass and mahogany stuff. I read that a microprocessor-based system is slated to replace the old circuitry; anyone want to guess if it'll still be intact 90 years after installation? Cheers, Chuck