Dot Matrix Printing

History

The conceptual roots of dot-based electromechanical printing trace to early telecommunications devices rather than to computers. Rudolf Hell's Hellschreiber (developed in the 1920s) is commonly cited as an early facsimile/teletype device that formed characters from a matrix of dots. It is a precursor concept rather than a computer printer, and the distinction matters: it demonstrated dot-formed characters but was not a serial impact printer driven by a digital host.

The technology as it applies to computing is known as serial impact dot matrix (SIDM) printing, and its origins are spread across several manufacturers working in parallel:

• OKI is credited with introducing an early serial impact dot matrix printer, the OKI Wiredot, in 1968.
• In 1970, Digital Equipment Corporation (DEC) introduced the LA30, and Centronics introduced the Centronics 101; both are widely cited among the first commercial dot matrix printers for the computer market.

Because several companies were developing similar solenoid-driven wire heads in roughly the same 1968-1970 window, the question of "who was first" is genuinely debated. Rather than crowning a single inventor, the honest record states each documented claim alongside its date. Early machines used coarse dot grids; higher-resolution multi-pin heads followed through the 1970s as office and personal computers proliferated.

How it works

The mechanism is electromechanical and physically direct:

• The print head carries a vertical column (or columns) of thin, stiff metal wires — the pins. Each pin is individually actuated by a small electromagnet/solenoid.
• To print, the controller energizes the appropriate solenoids, and each fired pin is thrust forward a fraction of a millimeter.
• The pin strikes an ink-soaked cloth ribbon, pressing it momentarily against the paper and leaving a single dot of ink. A small guide plate holds the ribbon and aligns the pins.
• The head traverses horizontally across the line — hence "serial" — firing pins in rapid, timed patterns so that accumulated columns of dots build up characters and images.
• After each line (or sub-line pass), the paper advances vertically and the process repeats.

Because every glyph is assembled from an addressable grid of dots rather than a cast letterform, one head can print arbitrary fonts, symbols, and bitmap graphics — the defining break from fully-formed-character impact devices.

Pin count governs quality. 9-pin heads form characters from a relatively coarse grid; text is legible but visibly dotted. 24-pin heads use a denser grid and can overlap dots, producing smoother output often marketed as near-letter-quality (NLQ) — generally at the cost of speed. Paper is typically continuous fanfold stock: a long perforated web, folded zig-zag, with sprocket (tractor-feed) holes along both edges that engage toothed wheels for precise, slip-free advancement.

Evolution

• Coarse early grids to finer grids. The earliest computer models used small dot matrices adequate for legible monospaced text; grids grew denser over the 1970s.
• 9-pin to 24-pin. The move to higher pin counts introduced NLQ output, letting dot matrix compete on appearance with daisy-wheel printers while retaining graphics capability.
• Standardized control languages. Epson's ESC/P, which originated with the MX-80 (1980) and was formalized in the early 1980s, became a de facto command standard. It was later extended as ESC/P 2 (scalable fonts, enhanced graphics) and spun off into ESC/POS for receipt printers.
• Displacement in general use. As inkjet and laser (non-impact) printers matured, dot matrix retreated from home and general office use into the impact-specific niches it still holds.

Advantages

These advantages are qualitative and documented; no per-unit performance figures are asserted.

• Prints multipart forms in one pass. Because it is an impact technology, the striking force transfers through carbon and carbonless multipart forms, producing multiple copies simultaneously — often on differently colored plies — something non-impact printers cannot do.
• Continuous-forms handling. Tractor-fed fanfold paper enables long, unattended runs and precise registration on pre-printed forms.
• Low consumable cost and robustness. Reliance on a simple cloth ribbon and a durable mechanical head suits high-volume, low-cost, and harsh-environment printing.
• Arbitrary fonts and graphics from a single head, unlike fixed-character impact printers.

Disadvantages

These disadvantages are likewise qualitative; no decibel, speed, or resolution figures are claimed.

• Noise. The mechanical striking of pins against ribbon and paper makes dot matrix printers characteristically loud relative to non-impact printers.
• Lower output quality. Even NLQ output is dot-formed and generally coarser than laser or inkjet; graphics resolution and color capability are limited.
• Lower speed than non-impact printers for general documents, and higher-quality dot matrix modes are slower still.

Modern use

Dot matrix printing persists where its impact nature is essential rather than incidental. Documented ongoing niches include multipart business forms and contracts, banking uses (such as passbook printing and certain check and receipt applications), point-of-sale and cash-register printing, and shipping and logistics documents.

The common thread is the need to mark carbon and carbonless multipart stock, or to run continuous forms cheaply and durably — requirements that non-impact printers structurally cannot meet. Where a document must be produced in duplicate or triplicate in a single physical pass, an impact head remains the only practical option.

Relationship to other technologies

• Versus daisy-wheel and typewriter (fully formed character impact): All are impact technologies, but dot matrix forms characters from a dot grid, so it can print graphics and arbitrary fonts; a daisy-wheel yields cleaner text but only its cast characters.
• Versus inkjet and laser (non-impact): Non-impact printers deliver higher resolution and quieter, faster general printing, but they cannot print through multipart carbon and carbonless forms — the very capability that keeps dot matrix alive.
• Versus thermal and receipt printing: Epson's dot matrix control-language lineage (ESC/P) directly seeded ESC/POS, used widely in thermal receipt printers, showing a technical continuity between dot matrix and modern receipt hardware.

Relationship to manufacturers

Companies documented in the technology's development and market include:

• OKI — credited with an early serial impact dot matrix printer, the Wiredot (1968).
• Digital Equipment Corporation (DEC) — the LA30 (1970), an early commercial model.
• Centronics — the Centronics 101 (1970); Centronics is also historically associated with the parallel printer interface.
• Epson (Seiko Epson) — maker of the landmark MX-80 (1980) and originator of the ESC/P command standard; long a dominant name in the category.
• NEC — adopted, in modified form, Epson's ESC/P during the dot matrix era.

Related printer families

• DEC LA30 — an early DEC dot matrix printer (1970).
• Centronics 101 — an early Centronics dot matrix printer (1970).
• OKI Wiredot — OKI's early serial impact dot matrix printer (1968).
• Epson TX-80 — Epson's early serial dot matrix printer, introduced in the late 1970s and a predecessor to the MX-80.
• Epson MX-80 — a 9-pin serial dot matrix printer (October 1980); the best-selling dot matrix printer of its era and the progenitor of ESC/P.

Timeline

1. 1920s

   Rudolf Hell's Hellschreiber, an early dot-matrix-based facsimile/teletype device (a precursor concept, not a computer printer).

2. 1968

   OKI Wiredot, an early serial impact dot matrix printer.

3. 1970

   DEC LA30 and Centronics 101 introduced; among the first commercial computer dot matrix printers.

4. 1978 (early)

   Epson TX-80, Epson's first serial dot matrix printer.

5. 1980 (October)

   Epson MX-80 released; 9-pin head; becomes the era's best-selling dot matrix printer.

6. Early 1980s

   Epson formalizes the ESC/P printer control language (originating with the MX-80); later extended as ESC/P 2 and adapted as ESC/POS.