Bolding mine.
LEDs? How modern.
Try incandescent lamps that sorta blurred from flickery to almost-solid but dim to almost-solid but brighter to eventually nearly full brightness as the time-averaged value of that particular bit moved from zero towards one.
You could sorta see the Instruction Counter doing a binary count-up for a short run, then jump to a totally different bit pattern with an interrupt, or jump to a slightly different pattern with a branch. Then watch it count up again for at most a second or two then jump again.
Meanwhile the air conditioner is roaring and I’m too tired to study & too keyed to nap. Yeah, the overnight shift babysitting one of the uni’s raggedy old mainframes was not a good job. It wasn’t dirty or smelly, but it wasn’t much fun either.