line printer
A high-speed impact printer, most often used by older mainframes, that prints an entire line in a single operation.
line printer: the drum that prints 132 characters at once
A line printer is an impact printer that produces a full horizontal line of text in a single strike, rather than building characters one by one. The most common type uses a rotating drum or chain bearing the complete character set, striking paper against a ribbon and platen in one synchronized blow. Speeds range from 300 to 1500 lines per minute depending on the model, making line printers the workhorse of batch data processing from the 1960s through the 1990s.
The IBM 1403 and its successors dominated the market, typically connected to mainframe computers and printing standard 132-column reports on continuous-form paper with perforated edges. The mechanical reliability was exceptional; a well-maintained line printer could run for years with minimal downtime. The noise level, however, was severe; a printing facility with multiple line printers operating simultaneously could exceed 90 decibels.
Mechanism and Variants
Line printers came in three main designs: drum printers with a fixed character set molded around a cylinder, chain printers with type slugs linked on a moving belt, and band printers using a flexible steel band. Drum printers offered speed but limited font flexibility. Chain and band printers allowed font changes by swapping the type element, though they were slower and more prone to jamming. Most industrial installations used chain or drum designs because repair parts were standardized and widely available.
Paper handling was mechanical and inflexible by modern standards. Operators fed continuous forms by threading the perforated margin through feed tractors, set the form depth on mechanical stops, and relied on the printer's hammers and paper motion to maintain registration. Multi-part forms were routine; the impact force easily penetrated three to five layers of carbon-backed stock.
Line printers became obsolete when laser printers achieved comparable speeds and cost by the early 2000s, but they survive in mission-critical environments where their mechanical simplicity and 24-hour uptime reputation still matter. Spare parts remain available from specialty vendors because replacing a line printer entirely is often cheaper than modernizing the mainframe infrastructure it feeds.