DECwriter
The DECwriter series was a family of
There were four series of machines, starting with the original DECwriter in 1970, the DECwriter II in 1974, DECwriter III in 1978, and the final DECwriter IV in 1982. The first three were physically similar, large machines mounted on a stand normally positioned above a box of
The DECwriters were among DEC's best-selling products, notably the II and III series.
DECwriter
The original DECwriter was introduced in November 1970 at the Fall Joint Computer Conference.
The LA30 used a 64-character
Mechanically, the machine was 2 by 2 feet (0.61 by 0.61 m) and came mounted on robust legs that raised the keyboard to standard desk height with the top 31 inches (790 mm) from the ground.
In June 1972, DEC introduced two new versions of the DECwriter, the LA30A which lacked a keyboard and was used as a dedicated printer, and the LA30-E which added an
DECwriter II
![](http://upload.wikimedia.org/wikipedia/commons/thumb/1/17/PDP_11-34%2C_by_the_U.S._Army_Natick_Soldier_Systems_Center%2C_April_18%2C_1978%2C_from_the_Digital_Commonwealth_-_commonwealth_4f16d844r.jpg/220px-PDP_11-34%2C_by_the_U.S._Army_Natick_Soldier_Systems_Center%2C_April_18%2C_1978%2C_from_the_Digital_Commonwealth_-_commonwealth_4f16d844r.jpg)
A replacement for the original product line was announced in August 1974 with the introduction of the DECwriter II series and its first model, the LA36.[8] The LA36 used the same basic printing mechanism as the LA30, and was physically similar although smaller and more rectangular. Like the LA30, the LA36 was also offered in a keyboard-less printer-only model, in this case known as the LA35.[8]
The primary change was the addition of a data buffer that allowed it to store characters. This meant the terminal could continue accepting data from the host computer while the printer was performing carriage returns or other time-consuming operations, and then resume printing without loss of data. When the print head fell behind, it began printing characters as fast as possible until the buffer was empty again, at speeds as high as 60 cps. This had the added advantage that the host computer did not have to insert fill characters, which in turn led to simpler interfacing requirements and reduced device driver complexity.[8]
There were numerous other changes as well. The character set now included a complete 128-character ASCII set, including upper and
The teleprinters were so popular that several third party companies introduced add-on cards to give the systems even more functionality. The Intertec Superdec offered 1200 bit/s support, double-wide characters, APL characters, and even user-defined character sets.
DECprinter I, new DECwriter IIs
The DECprinter I, model LA180, was introduced in September 1976. This was essentially a simplified version of the LA35, offered only with a Centronics port to provide speeds up to 180 cps.[12] In November, the same basic mechanism was used as the basis for new versions of the LA35 and LA36, differing primarily in using serial ports which made them easier to connect to DEC systems. These models went on to become one of DEC's best-selling products.[13]
DECwriter III
![](http://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Decwriter.jpg/220px-Decwriter.jpg)
January 1977 saw the introduction of the DECwriter III, or LS120.[14] This was a cost-reduced and improved version of the LA36 that supported only serial input out of the box, lacking the former current loop interface. Three new versions based on the LS120 were introduced in November 1978, the print-only LA120-RA DECprinter III, the LA120-DA which replaced the LA36 terminal, and the LA120-RB, otherwise similar to the RA but able to print on up to nine-thick copy paper as opposed to the normal six-thick of the base model.[15]
The LA120's were similar to the earlier models mechanically, with only minor changes to the layout of the printer and the floor stand. Internally, the primary change was the addition of a 1 kB character buffer, which allowed it to store many lines of text. The printer electronics examined the data, skipping over blank areas at high speed, and optimizing printing in both directions by reading backward through the buffer where appropriate. The overall speed increased to 180 cps. In addition to the character sets of the II series, the III added new character sets with National Replacement Character Sets for Finland, Denmark, Sweden, Germany, Norway, and France. It also offered eight options for character width (narrow or wide) and double-strike for bold.[15]
The LA120s normally were supplied with only an RS-232 interface, but the LA12X-AL add-on kit provided a current loop interface for those who still needed it, while the LA12X-BB added parallel interface, and the LA12X-CB connected to the Unibus. The LA12X-DL option expanded the character buffer to 4 kB.[15]
DECwriter IV
The first complete redesign of the DECwriter line was introduced in June 1982
Two models were offered, the LA34 which used a typewriter-like roller feed mechanism, and the LA38 which added a tractor feed mechanism, which could also be purchased separately for the LA34. Both fed paper in from the top, like a typewriter, and did not need any room below them for paper feeding.[16] The LA34 was not as suited for unattended printing of large volumes of data, since its friction feed was more prone to tracking skew and paper jams than its tractor feed siblings.
The DECwriter IV series also introduced optional support for DEC's
Letterwriter 100
Otherwise similar to the IV series, the LA100 series used a nine-pin print head and offered three different printing speeds to provide what DEC referred to as draft, memo, or letter qualities. In draft mode it printed at 240 cps, while in letter quality it used a 33 by 18 dot matrix that reduced the printing rate to 30 cps. As before, the LA100 was offered as the print-only Letterprinter 100 or a variety of Letterwriter 100 terminals.[19][20]
The internal character set ROM was further expanded to support the British, Finnish, French, Canadian French, German, Italian, Norwegian/Danish, Spanish, and Swedish character sets. More interesting was the addition of plug-in ROM cartridges containing the actual glyph data for the characters. The system could support two plug-in cartridges and as many as three internal ROMs (bare chips), to allow up to five character sets at a time.[21][20]
DECwriter Correspondent
The LA12 DECwriter Correspondent was a small form-factor terminal for portable use, weighing 20 pounds (9.1 kg).[22] Various models offered built-in modems or other interfaces. The system was otherwise similar to the IV series in features.[23][22]
Notes
References
Citations
- ^ Present 1978, p. 21.
- ^ a b DEC 1971, p. 1.1.
- ^ a b c DEC 1971, p. 1.2.
- ^ DEC 1971, p. 3.4.
- ^ DEC 1971, p. 2.2.
- ^ "Memories Cut Cost of PDP-8 Systems". ComputerWorld. 12 July 1972. p. 15.
- ^ "Decwriter LA30". 23 December 2019.
- ^ a b c d Present 1978, p. 47.
- ^ "Intertec advertisement". Computerworld. 22 May 1978. p. 49.
- ^ "LA36 Made Interactive". Computerworld. 19 December 1977. p. 30.
- ^ "Board Adds Features to Decwriter LA35, LA36". Computerworld. 4 December 1978. p. 37.
- ^ Present 1978, p. 59.
- ^ Present 1978, p. 60.
- ^ Present 1978, p. 76.
- ^ a b c Terminals 1983, p. Chapter 14.
- ^ a b Four 1981, p. 1.1.
- ^ Four 1981, p. 5.22.
- ^ Four 1981, p. 4.21.
- ^ Letterwriter 1982, p. ix.
- ^ a b Terminals 1983, Chapter 10.
- ^ Letterwriter 1982, p. ix, x.
- ^ a b "DEC Introduces New 'Correspondent'". Hardcopy. April 1982. p. 13.
- ^ Terminals 1983, Chapter 13.
Bibliography
- Letterwriter 100 Operator Guide (PDF). DEC. June 1982.
- Digital Equipment Corporation, 1957 to the Present (PDF). DEC. 1978.
- Terminals and Printers Handbook 1983-84. DEC. 1983.
- LA30 DECwriter Maintenance Manual (PDF). DEC. August 1971.
- DECwriter IV Series Technical Manual (PDF). DEC. October 1981.