Hold your hands palms-in, facing each other. Left hand is the A-side (opcodes 0–4). Right hand is the B-side (opcodes 9–5). Each finger is one operation. State starts at zero and lives on the paper in front of you — or here on the display above, or inside of your head, or all around you.
Every press applies one opcode to State. The trace records each step. INC (1) adds one. ADD (+) doubles. MUL (x) squares. EQU (=) holds. DEC (-) subtracts one. DIV (/) halves. MOD (%) returns the last digit. NOT (!) collapses any nonzero to 1. EXP (^) raises S to the power of itself.
To reach 4: press 1 + x — 0 → 1 → 2 → 4.
To reach 16: 1 1 + x — 0 → 1 → 2 → 4 → 16.
To reach 256: 1 1 + x = x — 4 → EQU → 4 → MUL → 16... continue.
BRK (0), the left thumb, halts all execution. Reset to begin again. The diagram below is the original paper.