Bendix G-15

Boots with a program loaded and running: a countdown 10 9 8 … 1 printed on the typewriter paper (right), computed by subtracting one from the accumulator AR each pass and testing its sign to close the loop. The drum lanes on the left show the 20 long lines and the fast lines; the amber column is the command word-time walking the command line, the one-plus-one link N pointing at the next command. Use the debugger to single-step one command, set a breakpoint on a command word-time, watch a drum word for writes, and read the disassembly of the G-15 command words (characteristic / source→destination / next-command N). A second configuration prints the running sum 10 19 27 … 55, accumulating into the PN register. The on-screen console gives Run / Stop / Step / Reset and a small typewriter keypad — the G-15 was operated from a typewriter and paper tape.

Boots with a program loaded and running: a countdown 10 9 8 … 1 printed on the typewriter paper (right), computed by subtracting one from the accumulator AR each pass and testing its sign to close the loop. The drum lanes on the left show the 20 long lines and the fast lines; the amber column is the command word-time walking the command line, the one-plus-one link N pointing at the next command. Use the debugger to single-step one command, set a breakpoint on a command word-time, watch a drum word for writes, and read the disassembly of the G-15 command words (characteristic / source→destination / next-command N). A second configuration prints the running sum 10 19 27 … 55, accumulating into the PN register. The on-screen console gives Run / Stop / Step / Reset and a small typewriter keypad — the G-15 was operated from a typewriter and paper tape.