BINAC
More info
- Creator
- Eckert–Mauchly Computer Corporation
- Released
- 1949
- Type
- Stored-program computer
- Memory
- 512 words of 31 bits, mercury delay lines
- Customer
- Northrop Aircraft
The machine with two processors running the same program and comparing answers after every instruction — 1949, and mostly remembered for nearly bankrupting its builders.
The Binary Automatic Computer was ordered by the aircraft maker Northrop, which wanted a navigation computer for a missile programme and seems to have pictured something that would fit on board. What arrived was two cabinets weighing close to 700 kg between them. The contract was for $100,000 and the cost came in near three times that, which nearly finished the Eckert–Mauchly Computer Corporation before Remington Rand bought it the following year.
The design was duplicated. Two identical arithmetic units executed every instruction in parallel and compared results before the next one was allowed to start; on a mismatch the machine halted. It was an early and unusually pure form of redundancy, motivated by the fact that vacuum tubes failed more or less constantly. Memory was mercury delay lines holding 512 words of 31 bits.
BINAC ran well enough at the builder's site during 1949. Then it was dismantled, shipped to California, and never really worked again — Northrop blamed the delivery, Eckert–Mauchly blamed the installation, and the machine was shelved. Whether it counts as the first working stored-program computer in the United States therefore depends on where you draw the line at "working".