200px, Datasaab D2 computer at IT-ceum 200px, Front panel D2 was a concept and prototype computer designed by

Datasaab Datasaab was the computer division of, and later a separate company spun off from, aircraft manufacturer Saab in Linköping, Sweden. Its history dates back to December 1954, when Saab got a license to build its own copy of BESK, an early Swedish c ...

Linköping Linköping () is a city in southern Sweden, with around 105,000 inhabitants as of 2021. It is the seat of Linköping Municipality and the capital of Östergötland County. Linköping is also the episcopal see of the Diocese of Linköping (Chu ...

, Sweden. It was built with discrete

transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch ...

s and completed in 1960. Its purpose was to investigate the feasibility of building a computer for use in an

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines. ...

to assist with

navigation Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation, ...

, ultimately leading to the design of the CK37 computer used in

Saab 37 Viggen The Saab 37 Viggen (Swedish language, Swedish for ''"the thunderbolt, Bolt"'' or ''"the Tufted Duck"'' (#Name, see name)) is a retired Swedish single-seat, single-engine, short-medium range combat aircraft. Development work on the type was init ...

. This military side of the project was known as SANK, or ''Saabs Automatiska Navigations-Kalkylator'' (''Saab's Automatic Navigational-Calculator''), and D2 was the name for its civilian application. The D2 weighed approximately 200 kg, and could be placed on a desktop. It used words of 20 bits corresponding to 6 decimal digits. The memory capacity was 6K words, corresponding to 15 kilobytes. Programs and data were stored in separate memories. It could perform 100,000 integer additions per second.

Paper tape Five- and eight-hole punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data storage ...

was used for input. Experience from the D2 prototype was the foundation for

's continued development both of the civilian D21 computer and military aircraft models. The commercial D21, launched already in 1962, used magnetic tape, 24 bit words, and unified program and data memory. Otherwise it was close to the D2 prototype, while a working airborne computer required a lot more miniaturization. The D2 is on exhibit at IT-ceum, the computer museum in Linköping, Sweden.

References

External links

D2 presented at the Datasaab's Friends' Society website
* {{commons, IT-ceum One-of-a-kind computers Science and technology in Sweden Transistorized computers