dot-matrix printer
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A dot matrix printer is an
impact printer In computing, a printer is a peripheral machine which makes a persistent representation of graphics or text, usually on paper. While most output is human-readable, bar code printers are an example of an expanded use for printers. Diffe ...
that prints using a fixed number of pins or wires. Typically the pins or wires are arranged in one or several vertical columns. The pins strike an ink-coated ribbon and force contact between the ribbon and the paper, so that each pin makes a small dot on the paper. The combination of these dots forms a dot matrix image. They were also known as serial dot matrix printers. While
inkjet Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpensi ...
and
laser printer Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively-charged cylinder called a "drum" to d ...
s technically exhibit
dot matrix printing Dot matrix printing, sometimes called impact matrix printing, is a computer printing process in which ink is applied to a surface using a relatively low-resolution dot matrix for layout. Dot matrix printers typically use a print head that moves ...
, they work differently than impact "dot matrix printers" and can deposit ink or toner at higher dot resolutions more quickly, with less inherent noise. The impact printer has the ability to make copies using multi-part forms, unlike an inkjet or laser printer.


History

In the 1970s and 1980s, dot matrix impact printers were generally considered the best combination of cost and versatility, and until the 1990s were by far the most common form of printer used with
personal Personal may refer to: Aspects of persons' respective individualities * Privacy * Personality * Personal, personal advertisement, variety of classified advertisement used to find romance or friendship Companies * Personal, Inc., a Washington, ...
and home computers. The first impact dot matrix printer was the Centronics 101. Introduced in 1970, it led to the design of the parallel electrical interface that was to become standard on most printers until it was displaced well over two decades later by the
Universal Serial Bus Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
(
USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
).
Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president unt ...
(DEC) was another major vendor, albeit with a focus on use with their PDP minicomputer line. Their LA30 30 character/second (CPS) dot matrix printer, the first of many, was introduced in 1970. In the mid-1980s, dot-matrix printers were dropping in price, and began to outsell
daisywheel printers Daisy wheel printing is an impact printing technology invented in 1970 by Andrew Gabor at Diablo Data Systems. It uses interchangeable pre-formed type elements, each with typically 96 glyphs, to generate high-quality output comparable to pre ...
, due to their higher speed and versatility. Increased pincount of the printhead from 7, 8, 9 or 12 pins to 18, 24, 27, or 36 permitted superior print quality, which was necessary for success in Asian markets to print legible CJKV characters. Epson's 24-pin LQ-series rose to become the new de facto standard, at 24/180 inch (per pass - 7.5 lpi). Not only could a 24-pin printer lay down a denser dot-pattern in a single-pass, it could simultaneously cover a larger area and print more quickly. Although the text quality of a 24-pin was still visibly inferior to a true
letter-quality printer A letter-quality printer was a form of computer impact printer that was able to print with the quality typically expected from a business typewriter such as an IBM Selectric. A letter-quality printer operates in much the same fashion as a typewr ...
such as a daisy wheel or laser printer, print quality was greatly superior to a 9-pin printer. As manufacturing costs declined, 24-pin printers gradually replaced 9-pin printers. By the dawn of the 1990s, inkjet printers became more common as PC printers.


DEC

Unlike the LA30's 80-column, uppercase-only 5x7 dot matrix, DEC's product line grew. New models included: * LA36 (1974): supported upper and lower case, with up to 132 columns of text (also 30 CPS) * LA34: a lower-cost alternative to the LA36 * LA38: an LA34 with more features * LA180: 180 CPS * LS120: 120 CPS * LA120: 180 CPS (and some advanced features) * LA12: a portable terminal - the DECwriter Correspondent


LA30

The DECwriter LA30 was a 30 character per second dot matrix printing terminal introduced in 1970 by
Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president unt ...
(DEC) of
Maynard, Massachusetts Maynard is a town in Middlesex County, Massachusetts, United States. The town is located 22 miles west of Boston, in the MetroWest and Greater Boston region of Massachusetts and borders Acton, Concord, Stow and Sudbury. The town's population w ...
It printed 80 columns of uppercase-only 7×5
dot matrix A dot matrix is a 2-dimensional patterned array, used to represent characters, symbols and images. Most types of modern technology use dot matrices for display of information, including mobile phones, televisions, and printers. The system is al ...
characters across a unique-sized paper. The printhead was driven by a
stepper motor A stepper motor, also known as step motor or stepping motor, is a brushless DC electric motor that divides a full rotation into a number of equal steps. The motor's position can be commanded to move and hold at one of these steps without any pos ...
and the paper was advanced by a noisy
solenoid upright=1.20, An illustration of a solenoid upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whose ...
ratchet Ratchet may refer to: Devices * Ratchet (device), a mechanical device that allows movement in only one direction * Ratchet, metonomic name for a socket wrench incorporating a ratcheting device * Ratchet (instrument), a music instrument and a ...
drive. The LA30 was available with both a
parallel interface In computing, a parallel port is a type of interface found on early computers (personal and otherwise) for connecting peripherals. The name refers to the way the data is sent; parallel ports send multiple bits of data at once (parallel c ...
(LA30-P) and a
serial interface In computing, a serial port is a serial communication interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits simultaneously in parallel. T ...
(LA30-S); however, the serial LA30 required the use of
fill character In computer terminology, a fill character is a character transmitted solely for the purpose of consuming time. It does this by filling a timeslot on a data transmission line which would otherwise be forced to be idle (empty). In this way, fill cha ...
s during the carriage-return. In 1972, a receive-only variation named LA30A became available.


LA36

The LA30 was followed in 1974 by the ''LA36'', which achieved far greater commercial success, becoming for a time the standard dot matrix computer terminal. The LA36 used the same print head as the LA30 but could print on forms of any width up to 132 columns of mixed-case output on standard green bar fanfold paper. The carriage was moved by a much-more-capable
servo drive A servo drive is an electronic amplifier used to power electric servomechanisms. A servo drive monitors the feedback signal from the servomechanism and continually adjusts for deviation from expected behavior. Function A servo drive receives a c ...
using a
DC electric motor An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force ...
and an optical encoder /
tachometer A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated anal ...
. The paper was moved by a stepper motor. The LA36 was only available with a serial interface but unlike the earlier LA30, no fill characters were required. This was possible because, while the printer never communicated at faster than 30 characters per second, the mechanism was actually capable of printing at 60 characters per second. During the carriage return period, characters were ''buffered'' for subsequent printing at full speed during a catch-up period. The two-tone buzz produced by 60-character-per-second catch-up printing followed by 30-character-per-second ordinary printing was a distinctive feature of the LA36, quickly copied by many other manufacturers well into the 1990s. Most efficient dot matrix printers used this buffering technique. Digital technology later broadened the basic LA36 line into a wide variety of dot matrix printers.


LA50

The DEC LA50 was designed to be a "compact, dot matrix" printer. When in graphic mode (as opposed to text mode), the printhead can generate graphic images. When in (
bitmap In computing, a bitmap is a mapping from some domain (for example, a range of integers) to bits. It is also called a bit array A bit array (also known as bitmask, bit map, bit set, bit string, or bit vector) is an array data structure that c ...
) graphics mode, the LA50 can receive and print
Sixel Sixel, short for "six pixels", is a bitmap graphics format supported by terminals and printers from DEC. It consists of a pattern six pixels high and one wide, resulting in 64 possible patterns. Each possible pattern is assigned an ASCII chara ...
graphics format.


Centronics 101

The Centronics 101 (introduced 1970) was highly innovative and affordable at its inception. Some selected specifications: * Print speed: 165 characters per second * Weight: 155 pounds (70.3 kg) * Size: 27 ½" W x 11 ¼" H x 19 ¼ D (approx. 70 cm x 29 cm x 49 cm) * Shipping: 200 pounds (approx. 91 kg), wooden crate, unpacked by removal of 36 screws * Characters: 62, 10 numeric, 26 upper case and 26 special characters (no lower case) * Character size: 10 characters per inch (10 "''pitch''") * Line spacing: 6 lines per inch (6 LPI) * Vertical control: punched tape reader for top of form and vertical tab * Forms thickness: original plus four copies * Interfaces: Centronics parallel, optional RS-232 serial


IBM 5103

The IBM 5103 was the only IBM printer that could be attached to the
IBM 5100 The IBM 5100 Portable Computer is a portable computer (one of the first) introduced in September 1975, six years before the IBM Personal Computer, and eight before the first successful IBM compatible portable computer, the Compaq Portable. It ...
, an early day portable computer. Printing was 8 DPI, 10 pitch, 6 LPI, and capable of printing bidirectionally from a 128 character set. Two models were offered: 80 and 120 characters per second.


Near Letter Quality (NLQ)

''Near Letter Quality'' mode—informally specified as almost good enough to be used in a business letter—endowed dot-matrix printers with a simulated typewriter-like quality. By using multiple passes of the carriage, and higher dot density, the printer could increase the effective resolution. In 1985, ''The New York Times'' described the use of "''near letter-quality,'' or NLQ" as "just a neat little bit of hype" but acknowledged that they "really show their stuff in the area of fonts, print enhancements and graphics." NLQ printers could generally be set to print in "draft mode", in which case a single pass of the print head per line would be used. This produced lower quality print at much higher output speed.


PC usage

In 1985, PC Magazine wrote "for the average personal computer user dot matrix remains the most workable choice". At the time, IBM sold
Epson Seiko Epson Corporation, or simply known as Epson, is a Japanese multinational electronics company and one of the world's largest manufacturers of computer printers and information- and imaging-related equipment. Headquartered in Suwa, Nagano, ...
's MX-80 as their IBM 5152. Another technology,
inkjet printing Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpens ...
, which uses the
razor and blades business model The razor and blades business model is a business model in which one item is sold at a low price (or given away for free) in order to increase sales of a complementary good, such as consumable supplies. It is different from loss leader marketing ...
(give away the razor handle, make money on the razor blade) has reduced the value of the low cost for the printer: "a price per milliliter on par with liquid gold" for the ink/toner.


Personal computers

In June 1978, the
Epson Seiko Epson Corporation, or simply known as Epson, is a Japanese multinational electronics company and one of the world's largest manufacturers of computer printers and information- and imaging-related equipment. Headquartered in Suwa, Nagano, ...
TX-80/TP-80, an 8-pin dot-matrix printer mainly used for the
Commodore PET The Commodore PET is a line of personal computers produced starting in 1977 by Commodore International. A single all-in-one case combines a MOS Technology 6502 microprocessor, Commodore BASIC in read-only memory, keyboard, monochrome monitor, an ...
computer, was released. This and its successor, the 9-pin MX-80/MP-80 (introduced in 1979/1980), sparked the popularity of impact printers in the personal computer market. The MX-80 combined affordability with good-quality text output (for its time). Early impact printers (including the MX) were notoriously loud during operation, a result of the hammer-like mechanism in the print head. The MX-80 even inspired the name of a noise rock band. The MX-80's low dot density (60 dpi horizontal, 72 dpi vertical) produced printouts of a distinctive "computerized" quality. When compared to the crisp typewriter quality of a daisy-wheel printer, the dot-matrix printer's legibility appeared especially bad. In office applications, output quality was a serious issue, as the dot-matrix text's readability would rapidly degrade with each
photocopy A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers u ...
generation.


PC Software

Initially, third-party printer enhancement software offered a quick fix to the quality issue. General strategies were: * doublestrike (print each line twice), and * double-density mode (slow the print head to allow denser and more precise dot placement). Some newer dot-matrix impact printers could reproduce bitmap images via "dot-addressable" capability. In 1981, Epson offered a retrofit
EPROM An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of programmable read-only memory (PROM) chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power s ...
kit called
Graftrax Dot matrix printing, sometimes called impact matrix printing, is a computer printing process in which ink is applied to a surface using a relatively low-resolution dot matrix for layout. Dot matrix printers typically use a print head that moves ...
to add this to many early MX series printers. Banners and signs produced with software that used this ability, such as
Broderbund Broderbund Software, Inc. (stylized as Brøderbund) was an American maker of video games, educational software, and productivity tools. Broderbund is best known for the 8-bit video game hits ''Choplifter'', ''Lode Runner'', ''Karateka'', and '' ...
's Print Shop, became ubiquitous in offices and schools throughout the 1980s. As carriage speed increased and dot density increased (from 60 dpi up to 240 dpi), with some adding color printing, additional typefaces allowed the user to vary the text appearance of printouts. Proportional-spaced fonts allowed the printer to imitate the non-uniform character widths of a typesetter, and also darker printouts. 'User-downloadable fonts' gave until the printer was powered off or soft-reset. The user could embed up to 2 NLQ custom typefaces in addition to the printer's built-in (ROM) typefaces.


Contemporary use

The desktop impact printer was gradually replaced by the
inkjet Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpensi ...
printer. When
Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...
's patents expired on steam-propelled photolithographically produced ink-jet heads, the inkjet mechanism became available to the printer industry. For applications that did not require impact (e.g. carbon-copy printing), the inkjet was superior in nearly all respects: comparatively quiet operation, faster print speed, and output quality almost as good as a laser printer. By 1995,
inkjet technology Inkjet technology originally was invented for depositing aqueous inks on paper in 'selective' positions based on the ink properties only. Inkjet nozzles and inks were designed together and the inkjet performance was based on a design. It was used a ...
had surpassed dot matrix impact technology in the mainstream market and relegated dot matrix to niche applications. , dot matrix impact technology remains in use in devices and applications such as: *
Cash register A cash register, sometimes called a till or automated money handling system, is a mechanical or electronic device for registering and calculating transactions at a point of sale. It is usually attached to a drawer for storing cash and other v ...
s, * ATMs, * Banking, passbook and cashiers checks, * Time cards and parking stubs * Multi-layer contracts for signature *
Fire alarm system A fire alarm system warns people when smoke, fire, carbon monoxide or other fire-related or general notification emergency, emergencies are detected. These alarms may be activated automatically from smoke detectors and heat detectors or may also ...
s, * Point-of-sale terminals, * British & Irish fire stations for turnout sheets * Applications requiring continuous output on fan-fold paper.
Thermal printing Thermal printing (or direct thermal printing) is a digital printing process which produces a printed image by passing paper with a thermochromic coating, commonly known as thermal paper, over a print head consisting of tiny electrically heated ...
is gradually supplanting them in some of these applications, but full-size dot-matrix impact printers are still used to print multi-part stationery. For example, dot matrix impact printers are still used at bank tellers and auto repair shops, and other applications where use of tractor feed paper is desirable such as
data logging A data logger (also datalogger or data recorder) is an electronic device that records data over time or about location either with a built-in instrument or sensor or via external instruments and sensors. Increasingly, but not entirely, they ar ...
and
aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...
. Most of these printers now come with USB interfaces as a standard feature, to facilitate connections to modern computers without legacy ports.


References

{{reflist History of computing hardware Impact matrix printers American inventions 20th-century inventions