ENIAC

Boots running the famous table-of-squares program (1, 4, 9, 16 ... by adding successive odd numbers), with the accumulator neon lamps lit. Every accumulator shows ten decades of ten lamps, one lit per decade — the glowing lamp is the digit. The bottom band shows the cycling-unit phase, the current program line, the master programmer count and the printer tape. Use the on-screen keypad (or the physical keys: Space/Enter = one pulse, P = initiate, O = stop, ← / → = step the program line, R = initial clear). Open the debugger to single-step the program-line pulses, set a breakpoint on a line, or watch an accumulator for writes.

Boots running the famous table-of-squares program (1, 4, 9, 16 ... by adding successive odd numbers), with the accumulator neon lamps lit. Every accumulator shows ten decades of ten lamps, one lit per decade — the glowing lamp is the digit. The bottom band shows the cycling-unit phase, the current program line, the master programmer count and the printer tape. Use the on-screen keypad (or the physical keys: Space/Enter = one pulse, P = initiate, O = stop, ← / → = step the program line, R = initial clear). Open the debugger to single-step the program-line pulses, set a breakpoint on a line, or watch an accumulator for writes.

Boots running the famous table-of-squares program (1, 4, 9, 16 ... by adding successive odd numbers), with the accumulator neon lamps lit. Every accumulator shows ten decades of ten lamps, one lit per decade — the glowing lamp is the digit. The bottom band shows the cycling-unit phase, the current program line, the master programmer count and the printer tape. Use the on-screen keypad (or the physical keys: Space/Enter = one pulse, P = initiate, O = stop, ← / → = step the program line, R = initial clear). Open the debugger to single-step the program-line pulses, set a breakpoint on a line, or watch an accumulator for writes.

Boots running the famous table-of-squares program (1, 4, 9, 16 ... by adding successive odd numbers), with the accumulator neon lamps lit. Every accumulator shows ten decades of ten lamps, one lit per decade — the glowing lamp is the digit. The bottom band shows the cycling-unit phase, the current program line, the master programmer count and the printer tape. Use the on-screen keypad (or the physical keys: Space/Enter = one pulse, P = initiate, O = stop, ← / → = step the program line, R = initial clear). Open the debugger to single-step the program-line pulses, set a breakpoint on a line, or watch an accumulator for writes.

Boots running the famous table-of-squares program (1, 4, 9, 16 ... by adding successive odd numbers), with the accumulator neon lamps lit. Every accumulator shows ten decades of ten lamps, one lit per decade — the glowing lamp is the digit. The bottom band shows the cycling-unit phase, the current program line, the master programmer count and the printer tape. Use the on-screen keypad (or the physical keys: Space/Enter = one pulse, P = initiate, O = stop, ← / → = step the program line, R = initial clear). Open the debugger to single-step the program-line pulses, set a breakpoint on a line, or watch an accumulator for writes.