SAAB had previously in 1957 constructed SARA, Swedens second computer (after BESK), to aid with calculations. That little beast used several hundreds of square meters. However, someone came up with the idea (considered as science fiction by then) to build a navigational computer to place in an airplane. With help of the invention of the transistor and very hard work the D2 (only 200 kg) was completed in 1960. The sucessor, D21, was sold to several countries and some 30 units was built. After that, several versions with names like D22, D220, D23, D5, D15, and D16 was developed. In 1971 the vision came true, and a computer (CK37) small and powerful enough to be used in an airplane was used in the fighter Saab 37 Viggen.
When the Swedish government needed 20 computers in the 1960s to calculate taxes, an evaluation between Saab's and IBM's machines proved Saab's better. Later the D5s was used to set up the first and largest bank terminal system for the Nordic banks, a system which was partly in use until the late 1980s.
When Intel sued the competitor UMC a few years ago for patent infringement over technologies including microcode updates of processors and different parts of the processor working asynchronously, UMC could point to an awarded paper describing how these technologies had been used in the D23 already in 1972. Since Intel's patents were from 1978, that paper would prove prior art and imply that the patents never should had been granted at all. The case was later dropped.
The arguably two most influential entrepreneurs behind Datasaab were Viggo Wentzel and Gunnar Lindström, the latter is even today associated with the building where Datasaab resided in its glory days, a huge house close to the train station in Linköping commonly called "Gunnars fabrik" ("Gunnars factory".)