Line Printing

History

Line-at-a-time printing grew directly out of punched-card accounting (tabulating) machinery rather than appearing suddenly. Documented milestones include U.S. Census tabulators that could print results around 1910, and IBM printing accounting machines beginning in 1920. The IBM 405, introduced in 1934, could print at 80 lines per minute, and the IBM 407 Accounting Machine (1949) used a type-wheel mechanism rated at 150 alphanumeric lines per minute. Early stored-program computers were paired with line printers as well: IBM's first commercial computer, the IBM 701, used the IBM 716 printer, which was based on the 407's type-wheel design.

The device most often treated as the archetypal line printer is the IBM 1403, introduced in 1959 as part of the IBM 1401 system. Its chain mechanism produced print quality that IBM and later commentators describe as the long-standing benchmark for high-speed impact printing. The 1401/1403 combination was enormously popular during the era, and the 1403 remained in IBM's line for decades, discontinued in 1983.

The specific individual inventor of the chain-printing mechanism is not identified in the authoritative public sources consulted here. It is documented as an IBM engineering development that debuted commercially with the IBM 1403 Model 1 in 1959, and any single-name "inventor" claim should be treated as unverified.

How it works

A line printer carries a full font of raised (embossed or engraved) character type on a moving carrier positioned in front of the paper, with an inked ribbon between the type and the paper and a bank of individually controlled electromagnetic hammers behind the paper — typically one hammer per print column. As the desired character for a given column sweeps past that column's position, the hammer fires, pressing the paper and ribbon forward against the type slug to print the character. Because every column has its own hammer, all characters of a line are printed during a single pass of the type carrier rather than sequentially.

The precise firing moment is critical. On the IBM 1403 the hammer pushes the paper from behind into the ribbon and the passing chain slug. The interval known as "flight time" was adjustable, and timing errors produced characteristic defects: on drum printers, characters that wander vertically; on chain, train, and bar printers, characters shifted horizontally. A noted design advantage of the horizontally moving chain is that its residual vibration ("jitter") is horizontal, a direction to which the human eye is relatively insensitive, which helped preserve perceived quality.

Paper is continuous fan-fold stock with perforated sprocket margins, pulled through by tractor feeds (sprockets or sprocket belts), so the machine can advance and skip lines at high speed between printed lines.

Evolution

Several distinct carrier mechanisms were developed over the technology's life:

• Bar printers: type mounted on fingers on a bar that shuttled left-to-right and back; slower and less expensive. The IBM 1443 is cited as an example.
• Drum printers: a full character set engraved around the circumference of a rotating drum, with hammers firing as the wanted character rotates into position. Some low-cost models used one hammer per two columns, needing two drum revolutions per line.
• Chain printers: type slugs carried on a horizontally moving loop or chain; the type is typically operator-changeable, and vertical alignment is superior to drum designs. This mechanism debuted on the IBM 1403 Model 1 in 1959.
• Train printers: mechanically similar to chain printers, but the print slugs ride inside a machined track "resembling railroad cars." IBM introduced this in 1967 on the IBM 1403 Model N1.
• Band printers: characters embossed or etched onto a thin flexible steel band; developed in the late 1960s to lower cost while keeping good quality.

IBM documents its hammer-based impact line printers as spanning 1959 to 1999, with newer mechanisms progressively replacing older drum-type technology.

Advantages

Line printers offered a set of documented, qualitative advantages that made them the standard for high-volume output:

• High throughput for the era: printing a whole line per operation gave speeds far above character-at-a-time printers, making line printers the standard for high-volume batch output.
• Print quality: the chain-type mechanism of the IBM 1403 is repeatedly cited as the standard of quality for high-speed impact printing, not matched until later laser technology.
• Alignment robustness: on chain and train designs, horizontal jitter is less visually objectionable than vertical wander, and these designs give superior vertical character alignment compared with drum printers.
• Operator-changeable type: chain designs allowed the type to be removed and replaced within a few minutes, enabling different fonts, character sets, and specialized (for example, numeric-heavy) sets.
• Continuous-forms handling: tractor-fed fan-fold paper and fast line-skip supported unattended, high-volume runs and multipart (carbon) forms.

Disadvantages

The same impact design imposed documented, qualitative limitations:

• Impact noise: as impact devices with banks of hammers and fast-moving carriers, line printers were loud; the Computer History Museum describes a running 1403 as a clattering chain printer.
• Fixed character repertoire: only characters present on the drum, chain, train, or band can be printed, so arbitrary fonts and graphics are not supported the way they are on later dot-matrix or laser printers.
• Critical, adjustable timing: hammer flight time had to be tuned, and misadjustment produced vertically wandering (drum) or horizontally shifted (chain, train, bar) characters.
• Mechanical complexity and maintenance: many moving parts — chains, trains, bands, hammer banks, ribbon transport, and tractors — demanded servicing, and drum designs faced alignment limits that motivated the shift to chain, train, and later band mechanisms.
• Consumables and format constraints: operation depended on inked ribbons and standardized continuous fan-fold forms with sprocket margins.

Modern use

Line printers were progressively displaced by laser printers, which surpassed them on quality, and by dot-matrix and other technologies. IBM's impact line-printer lineage is documented as running until 1999.

Today they are effectively historical, preserved and demonstrated in museum settings. Notably, the Computer History Museum operates restored, running IBM 1401 systems with IBM 1403 printers, revived and maintained by volunteer former IBM engineers. Impact line printers — including band and later "line matrix" successors — survived longest in niches needing multipart carbon forms, though specific current-market claims are outside the scope of the verified sources here.

Relationship to other technologies

Line printing sits within a clear lineage of printing methods:

• Predecessors: punched-card accounting and tabulating machines with type-bar and type-wheel printing (such as the IBM 285, 402, 405, and 407) are the documented ancestors of computer line printers.
• Contemporaries and alternatives: character-at-a-time printers derived from typewriters were slower; line printers were the high-volume option.
• Successors: laser printing later surpassed line printers on quality, while dot-matrix and line-matrix (comb or hammer-bank dot) printers offered graphics and flexible fonts.
• Software and cultural legacy: the Unix spooling commands lp and lpr and the PC parallel-port designations LPTx all derive from "line printer." The 132-column report width also became a lasting standard, inherited from accounting-machine paper sizing (14 7/8-inch stock) rather than any strict technical necessity — a wide variety of widths existed.

Relationship to manufacturers

Several companies are documented as makers of line and impact printers:

• IBM is the most prominently documented maker, producing type-bar, chain, train, and band hammer printers from 1959 to 1999, with the 1403/1401 pairing being iconic.
• Dataproducts is documented for drum and band printers, including a band-printer range named by speed.
• Printronix and TallyGenicom are documented for comb/line-matrix printers; TallyGenicom was acquired by Printronix in 2009.
• Potter Instrument is documented via the "Potter Flying Typewriter" drum printer of the early 1950s.

Related printer families

Documented product-line names tied to line and impact printing include:

• IBM 716 — line printer for the IBM 701.
• IBM 1403 — chain from 1959; train from Model N1 in 1967.
• IBM 1443 — a bar printer.
• IBM chain/train family — IBM 5203, 3211, 3216, 3811, and 3203.
• IBM band-printer family — IBM 3618, 3288, 3776, 5211, 3262, 5262, 4245, 4248, and 6262.
• Dataproducts band-printer range — named by lpm rating (for example, B300, B600, B1000).
• IBM accounting-machine ancestors — 285, 402, 405, and 407.

Timeline

1. c. 1910

   U.S. Census Bureau tabulators can print results.

2. 1920s

   IBM introduces printing accounting machines (beginning 1920).

3. 1934

   IBM 405 documented printing at 80 lines per minute.

4. 1949

   IBM 407 Accounting Machine, type-wheel mechanism, documented at 150 alphanumeric lines per minute.

5. early 1950s

   Potter "Flying Typewriter" drum printer; the IBM 701 uses the IBM 716 line printer.

6. 1959

   IBM 1403 introduced with the IBM 1401; chain mechanism, Model 1.

7. 1967

   Train mechanism introduced with the IBM 1403 Model N1.

8. late 1960s

   Band (flexible steel band) printer technology developed.

9. 1970s–1990s

   Successive IBM chain/train and band families (3211, 3203, 3262, 4245, 4248, 6262, and others).

10. 1983

    IBM 1403 discontinued.

11. 1999

    End of IBM's documented hammer/impact line-printer production span.