Line printer

The line printer emerged because batch computing generated output faster than any existing technology could render it. By 1952, UNIVAC I could process thousands of records per hour, but teleprinters—the standard computer output device—printed at ten characters per second. A job that computed in minutes required hours to print. The adjacent possible was clear: business data processing needed printers 100 times faster than teletypes.

The solution arrived from multiple directions simultaneously. Potter Instrument Company's "Flying Typewriter" drum printer reached 300 lines per minute in 1952. Remington Rand's High-Speed Printer for UNIVAC achieved 600 LPM by 1954—consuming 18 kilowatts and requiring eight gallons of chilled water per minute for cooling. Burroughs pushed wire-based dot matrix printing to 1,000 LPM for shorter lines. But the definitive machine was IBM's 1403, released in October 1959 alongside the IBM 1401 computer.

The 1403's genius lay in its chain mechanism: 240 character slugs—five identical sets of 48 characters—racing around a loop at 5.2 meters per second while 132 electromagnetically-actuated hammers fired with microsecond precision. The result was four times faster than competitors at launch and print quality "the best until laser printers." IBM delivered over 23,000 units through the early 1980s. By the late 1960s, half the world's continuous forms—the green-bar paper of data processing—printed on 1403s.

The cascade shaped computing's architecture. Batch processing dominated through the 1970s: jobs queued during business hours, ran overnight, and generated stacks of printed reports delivered the next morning. The 132-column width became an industry standard, inherited from IBM 407 accounting machines. When IBM introduced the 1401 at $2,500 monthly rental versus $43,000 for its predecessors, line printers made computing accessible to medium-sized businesses. Over 10,000 IBM 1401 systems deployed—each one feeding its reports through a line printer that had become as essential as the computer itself.