The Diablo 630 was a daisy wheel printer

Daisy wheel printer

Daisy wheel printers use an impact printing technology invented in 1969 by David S. Lee at Diablo Data Systems. It uses interchangeable pre-formed type elements, each with typically 96 glyphs, to generate high-quality output comparable to premium typewriters such as the IBM Selectric, but two to...

 (computer printer

Computer printer

In computing, a printer is a peripheral which produces a text or graphics of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most new printers, a...

) sold by the Diablo Data Systems

Diablo Data Systems

Diablo Data Systems was a division of Xerox created by the acquisition of Diablo Systems Inc. in 1972.It is best known for the Diablo 630 daisywheel printer, but also produced the hard disk drives that were resold by DEC as the RK02 and RK03....

 division of the Xerox Corporation from 1980. The printer was capable of letter-quality printing

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 typewriter...

; that is, its print quality was equivalent to the quality of an IBM

IBM

International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 Selectric typewriter, Selectric-based printer, or similar quality printer. The printer was capable of this quality at a nominal speed of 30 characters per second (roughly twice the speed of the Selectric).

Several technologies enabled this quality and speed:

• The lightweight daisy wheel was rotated by a closed-loop servo
  Servomechanism
  thumb|right|200px|Industrial servomotorThe grey/green cylinder is the [[Brush |brush-type]] [[DC motor]]. The black section at the bottom contains the [[Epicyclic gearing|planetary]] [[Reduction drive|reduction gear]], and the black object on top of the motor is the optical [[rotary encoder]] for...
  
   and could be positioned rapidly and accurately. Because the wheel could turn in either direction, the next character was never more than 180° away from the previous character (and related characters were grouped together so the average "seek" was much less than 180°).
• Like the element on a Selectric the daisy wheel could be easily changed, allowing a wide variety of font
  Font
  In typography, a font is traditionally defined as a quantity of sorts composing a complete character set of a single size and style of a particular typeface...
  
  s and character pitches.
• Some models supported wheels with two rows of characters, allowing for the machine to print in two different languages or with a large set of special symbols.
• The printer used cartridge-loaded ribbons; both an economical endless cloth ribbon and a high-quality single-use film ribbon were available with colored ribbons provided by third parties. By contrast, Selectric-based printers could use only one type of ribbon—cloth or single-use carbon film—and were almost always equipped for the former for economic reasons.
• The carriage was also servo-controlled and the printer could print with the carriage moving either forwards or backwards, saving most of the time that would otherwise be spent executing carriage-returns.
• The servo control of the carriage permitted the use of proportional spaced fonts, wherein each character does not have to occupy the same amount of horizontal space.
• Unlike Selectric-based printers, daisy wheel printers support the entire ASCII
  ASCII
  The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
  
   printing character set.
• Bidirectional paper motion was similarly servo-controlled allowing quick printing of subscripts and superscripts as well as fast slewing past white space.
• Servo control of both paper and carriage permitted the unit to be used for plotting, with resolution of 120×48 steps per inch. This was popular enough that special daisy wheels were made with a reinforced period (.), the character most often used for plotting.
• The logic permitted simultaneous motion of the wheel, the carriage, and the paper. The hammer automatically struck only after all three motions completed. This minimized the time spent waiting for the motions to complete.

A related model, the Diablo 1620, included a keyboard and strongly resembled a slightly overgrown Selectric typewriter. It in fact could be used as either an offline typewriter or as an interactive computer terminal. Unfortunately for a typist, the daisy wheel mechanism hides the area just printed. Firmware in the machine would therefore make the carriage move quickly to the right of the typing position, revealing the most recently typed characters, after a few moments of inactivity. This was disconcerting to many users. Only a very slow typing speed would allow the wheel to get out of the way after every character; faster typing speeds resulted in the wheel continuously hiding the typed copy until the typist paused. This made checking the copy for errors a bit more awkward and slow than on Selectric-based terminals.

The same mechanism was used in Xerox's 850 display typing system and 860PDS word processor, and was also sold to OEM

OEM

OEM means the original manufacturer of a component for a product, which may be resold by another company.OEM may also refer to:-Computing:* OEM font, or OEM-US, the original character set of the IBM PC, circa 1981...

s. One notable user was Digital Equipment Corporation

Digital Equipment Corporation

Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...

 who resold the printer as the LQP01 (with a parallel interface) and the LQPSE (with an RS232 serial interface) and supported by Digital's WPS-8

WPS-8

WPS-8 was the name of a Word Processing System sold by Digital Equipment Corporation for use with their PDP-8 processors ....

 word processing

Word processing

Word processing is the creation of documents using a word processor. It can also refer to advanced shorthand techniques, sometimes used in specialized contexts with a specially modified typewriter.-External links:...

software.

The printer became so common, with so much software supporting its command language, that Diablo emulation became an expected feature on other daisy-wheel printers and even on early laser printers. This was so pervasive that at least one company lived by testing printers for full Diablo 630 compatibility.

External links

• Diablo Model 630/630 ECS Printers/Terminals API Interface Complete description of printers and command language, with all modes
• Brief description of Diablo 630 command language