Card-Programmed Calculator
More info
- Creator
- IBM, from a Northrop Aircraft design
- Released
- 1949
- Type
- Card-controlled calculator
Unit-record equipment cabled together into something that was nearly a computer — and that sold far better than IBM expected.
In the late 1940s engineers at Northrop Aircraft wired an IBM electronic multiplier to an accounting machine so that the multiplier's results could be printed and fed straight back into the next step. They called it the poor man's ENIAC. IBM looked at the hack, engineered it properly as a 604 attached to a 402, and sold it from 1949 as the Card-Programmed Electronic Calculator.
The program was a deck of cards, one instruction per card, which meant the machine's clock rate was the card reader's feed rate. The plugboard determined what a card could mean at all; the deck determined the order. A loop meant feeding the same cards through again, and conditional execution was done with selectors on the board. There was no stored program, and nobody claimed otherwise.
Around 700 were built. The whole American aircraft industry did its numbers on them until the IBM 650 and 701 appeared, and the lasting effect is that an industry learned to think in programs before it had access to computers.