LGP-30

Boots with a program loaded and running. The default "Flexowriter hello" types HELLO WORLD onto the typewriter paper (right): five characters are packed into each 31-bit word and printed one at a time by the p (print) order, shifting the accumulator left six bits between characters — the whole of the LGP-30's output was the Flexowriter. The drum on the left is the 64 tracks × 64 sectors (4096 words) of magnetic memory; lit cells are non-zero, the blue column is the drum sector rotating under the read/write heads, and the bright cell is the order being executed. Use the debugger to single-step one order, set a breakpoint on a drum address, watch a drum word for writes, and read the disassembly of the sixteen LGP-30 orders (z b y r i d n m p e u t h c a s). A second configuration counts down 9 8 7 … 0, subtracting one from a drum counter each pass and testing the accumulator sign to close the loop, typing each value with the decimal-typeout print. The on-screen console gives Run / Stop / Step / Reset and a Flexowriter keyboard whose letters type onto the paper and feed the i (input) order.

Boots with a program loaded and running. The default "Flexowriter hello" types HELLO WORLD onto the typewriter paper (right): five characters are packed into each 31-bit word and printed one at a time by the p (print) order, shifting the accumulator left six bits between characters — the whole of the LGP-30's output was the Flexowriter. The drum on the left is the 64 tracks × 64 sectors (4096 words) of magnetic memory; lit cells are non-zero, the blue column is the drum sector rotating under the read/write heads, and the bright cell is the order being executed. Use the debugger to single-step one order, set a breakpoint on a drum address, watch a drum word for writes, and read the disassembly of the sixteen LGP-30 orders (z b y r i d n m p e u t h c a s). A second configuration counts down 9 8 7 … 0, subtracting one from a drum counter each pass and testing the accumulator sign to close the loop, typing each value with the decimal-typeout print. The on-screen console gives Run / Stop / Step / Reset and a Flexowriter keyboard whose letters type onto the paper and feed the i (input) order.