My first computer job (in high school) was working at the University of Cincinnati Medical School computer center, where we had an IBM 7040/1401 *tape* system (no disk!). The bulk of our computing work involved very long statistical regressions (some took all weekend) and radiation treatment planning (basically the inverse problem to a CAT scan). (Google University of Cincinnati Medical School and its dubious ethical history -- especially with DoD and radiation studies.) We also trained *blind programmers* (Google Dr. Theodore Sterling), who worked with the SW we developed for printing Braille on an IBM 1403 printer modified with a soft cloth behind the paper so that the paper would bulge after being hit with a ".". One of the blind programmers got so good at "reading" these 14" wide Braille printouts that he took his shirt off and simply pressed the printout against the skin on his chest! After our IBM "customer engineer" told us that computers interfered with radio reception -- and demonstrated this with a portable transistor radio -- the blind programmers started using this radio "side-channel" to let them know how their program was progressing. For them, it was the equivalent of our "blinking lights". (We didn't attempt to compute large powers modulo large primes, but these computers would have been so slow that one could have written down the bits of the exponents by hand from the radio signals.) At 09:25 PM 4/8/2018, Tomas Rokicki wrote:
I remember both the HP-21MX and PDP-11 lights as "glowing with varying brightness" but you could still figure out what your code was doing by just *how* bright individual bits were . . . I'm going to have to make a USB blinky-lights console for my Mac . . . maybe I'll put some toggle switches on it too.