In D21, parts of the D2 solutions were used, but the computer got at quite new architecture, worked out in cooperation between Börje Langefors and the SARA construction team.

The first D21 computer was installed at SEV (Skandinaviska Elverk) who also gave impulses to the construction work.


D21 at the customer Skandinaviska Elverk


D21 at the SARA basement at Saab in Linkoping.


The control board and the paper tape reader of D21. The magnetic tape station in the background was produced by Potter.


Test of a D21.

Programming. Bengt Asker.

Demonstration of D21.
From left: Per Eckerberg, Tryggve Holm, Sören Segerborg.

Demonstration of D21.

Yngvell has a lesson.


This enormous desk memory was adapted to D21 at the point of time for creating a central people register in Sweden. This was one of the first so called mass memories.
Producer: Bryant.
Capacity: 5 MByte.


The standardized unit circuits of D21 were made by discrete components mounted together to a module.

The drawings to this “tanker” were produced by means of the D21. The tanker was built at the Kockum Shipyard in the middle of the 60 th.