First electronic computer to ship 1,000 units

The first computer with an installed base of more than 1,000 machines was the IBM 650 Magnetic Drum Data Processing Machine. The first 650 was delivered to the John Hancock Mutual Life Insurance Company in Boston, Massachusetts on 8 December 1954, and the model remained in production until 1962. Almost 2,000 were produced in total.

The IBM 650 was the company's first attempt at a computer targeted at business customers. IBM's previous offerings had been either one-off experiments or, as was the case with the IBM 701, only marketed to research institutions and government bodies. It was developed in the early 1950s, and the company expected to sell as many as 50 units. The computer cost $150,000 to buy (equivalent to about $1.45 million in 2020 dollars), but most customers instead leased their machines from IBM at a rate of $3,250 per month (around $31,000 today).

It quickly became apparent that the forecasters had greatly underestimated the market for computers. By mid-1955 more than 75 customers had taken delivery of a 650, and by April 1956 this installed base had grown to 212 machines (with another 873 ordered, but not yet delivered). Production accelerated to an unprecedented rate of one computer per day in the mid-1950s, requiring the adoption of production-line techniques in what was previously a meticulous one-at-a-time process.

The basic IBM 650 came as three separate modules. The computer itself (the CPU) was the Type 650 Console Unit, which measured approximately 5 ft x 3 ft x 6 ft (1.52 m x 0.91 m x 1.82 m) and weighed 1,966 lb (891 kg). In the computer's most basic form it was packaged with the similarly sized Type 655 Power Supply Unit and the Type 533 Input-Output Unit. Each unit came with castors, making it relatively easy to install and move when necessary (a world away from older computers that had to be built on-site and filled multiple rooms).

To run the 650, the operator had to use the Type 553 punch-card reader to input programming instructions, as well as any data they wanted to work with. Once the "deck" of punch cards was set up, the operator run the program from the "console", which had an array of switches that controlled the behaviour of the machine. There was no display, the results were outputted as punched cards.

The 650 was a generally well-liked machine by those who used it. The console allowed for a significant amount of real-time control (complete with blinkenlights to show what was happening).