After a exorcising a few gremlins (a diode around the wrong way, and a couple of unsoldered(!) joints), the program counter is working. As usual, here's a blinky video. The counter resets, counts up to 63 (i.e. the complete address space), then address values 0x15 and 0x2A are loaded a couple of times. MSB is top right, LSB is bottom left:

It's interesting that the camera autofocus has a few burps. I guess the LEDs are putting out a fair amount of infrared!