Switch shifter

// A 74HC165 reading eight switches, slowly enough to watch.
//
// The DIP switch is a byte: switch 1 is bit 0, switch 8 is bit 7, and a
// switch that is on (lever up) is a 1. It starts at 1011 0010.
//
// Press and hold LOAD: PL goes low and the 165 copies all eight switches into
// its register at once. Q7 shows bit 7 right away, so the LED lights for a
// 1 and stays dark for a 0.
//
// Let go, and every rising edge of the 1 Hz clock shifts the register one place
// towards Q7: bit 6, bit 5 ... bit 0 come out on the LED one second at a time,
// most significant first. Then zeros, because DS (the serial input at the far
// end) is tied to ground. Change a switch and press LOAD again.
//
// A microcontroller does exactly this, only fast: pulse PL low, then
// shiftIn(Q7, CP, MSBFIRST) reads the byte with eight clocks. Three pins for
// eight switches, and a second 165 chained off Q7 would make it sixteen.