Manchester Mark 1

Boots with a program loaded and running: the factorial series 1! 2! 3! … 10!, each result printed on the teleprinter paper (right) as its dot pattern is computed on the Williams-tube store (left). The amber marker is the control register CI walking the program; the B-line index registers appear under the header. Use the debugger to single-step one instruction, set a breakpoint on a store line, watch a line for writes, and read the disassembly of the Mark 1 function codes. The second configuration prints a table of squares by using a B-line as an index register (the Mark 1 innovation). The on-screen panel gives Run / Stop / Step / Reset — the Mark 1 had a console of switches and hand-keys, not a typewriter keyboard.

Boots with a program loaded and running: the factorial series 1! 2! 3! … 10!, each result printed on the teleprinter paper (right) as its dot pattern is computed on the Williams-tube store (left). The amber marker is the control register CI walking the program; the B-line index registers appear under the header. Use the debugger to single-step one instruction, set a breakpoint on a store line, watch a line for writes, and read the disassembly of the Mark 1 function codes. The second configuration prints a table of squares by using a B-line as an index register (the Mark 1 innovation). The on-screen panel gives Run / Stop / Step / Reset — the Mark 1 had a console of switches and hand-keys, not a typewriter keyboard.