Gerrit Blaauw

Gerrit Anne Blaauw was born in 1924 in The Hague. Blaauw's interest for computers was triggered by an article about the American machine Mark I. During the Second World War he studied in Delft where he received his Bachelor degree magna cum laude a year after the war. Blaauw studied electronic engineering at Harvard University, Cambridge, Massachusetts, USA. In 1949 he received the title Master of Science. He also received his Ph.D. in 1952 at the same university.

Blaauw worked at the ARRA II and FERTA while he was at the Mathematical Center. You can read more about those machines elsewhere on this website.


At Harvard Blaauw worked under supervision of Howard Aiken. The department of Howard Aiken built its own computers financed by the navy. Howard's department created highly reliable machines, using established technology. Blaauw received his Ph.D. for his contributions at the architecture of the Harvard Mark IV. For getting a scholarship, after finishing his study in Harvard, Blaauw had to come back to the Netherlands. Maybe it is because of the influence of Aiken that the law of Blaauw became famous during his time working for IBM: "Established technology tends to persist in the face of new technology"[1].

Blaauw at ARRA II

Blaauw working at the ARRA II computer.

In 1952 Blaauw joined the Mathematical Center (MC) in Amsterdam after 5 years of experience in building computers in the United States. At the MC, Blaauw started working on the ARRA II together with C.S. Scholten and B.J. Loopstra. The ARRA II followed up the ARRA. As will be clear from the article about the ARRA I, this machine was a great disaster, since it never really worked like intended. When Blaauw joined the team at the Mathematical Center for building the ARRA II, he just needed around 20 minutes to explain Scholten and Loopstra why the design of the first ARRA needed to be thrown away. Like every other place Blaauw worked, he worked very precisely using an architecture plan.

Finished building the ARRA II, Blaauw built another ARRA-like machine during his time at the MC. This time for plane manufacturer Fokker. This machine was called FERTA, which was used for designing the very popular airplane called the Fokker Friendship (1955). This plane received the Dutch award for best design[2].

Blaauw is the inventor of the Blaauw box, which made virtual addressing of memory possible. It was originally designed for the original IBM System 360, but it wasn't actually put in the machine until its 67th revision.


After this relative short period of working at the MC, Blaauw left and joined the IBM research lab at Poughkeepsie, New York, USA. During this period Blaauw became famous for his methodological manner of building computer machines. He made a difference between architecture, implementation and realization of a machine. After a couple of years working on some different machines, one of the most famous machines built by Frederick Brooks, Gerrit Blaauw and Gene Amdahl was the IBM System/360, which was introduced in 1964. IBM Board Chairman Thomas J. Watson Jr. called the event the most important product announcement in the company's history[3]. The number 360 (degrees) already explains that this machine can do all kind of jobs. For the first time in computer building history, systematic design principles were used to build this success-story machine. This machine is sometimes called the first modern computer, because of its all round possibilities. Some very common terms nowadays, introduced for the first time in the IBM System/360 are:

  • Byte: The 360 was the first 8-bit design machine
  • I/O: The multiplexer channel was able to handle I/O to and from several devices simultaneously at the device's highest rated speeds.
  • Timesharing: This means sharing computer resources among many users using small slices of time.
  • Multiprogramming: This concept of running multiple programs parallel on one machine was formally described by E.W. Dijkstra, see EWD126 and EWD196[4] and introduced during the same period in the Electrologica X8
  • Paged Virtual Memory:, which was removed from the first version of the System 360. In revision 67 of the System 360 it was implemented for the first time in a commercially sold computer. This revolutionary address translation system was also called the "Blaauw Box."
  • Architecture: Blaauw was responsible for the architecture of the System/360. The term architecture was described as follows: "Computer architecture, like other architecture, is the art of determining the needs of the user of a structure and then designing to meet those needs as effectively as possible within economic and technical constraints," which was written by Fred Brooks in the report "Project Stretch" in 1962.


The most important methodology of Blaauw is making a difference between architecture, implementation and realization. Blaauw described this difference as follows in an interview in "The Persistence of the Classical Computer Architecture. A Survey from 1950 to the present" in 1990:

"Architecture concerns the function that is provided to the programmer, such as addressing, addition, interruption, and input/output. Implementation concerns the method which is used to achieve this function, perhaps a parallel data path and a microprogrammed control. Realization concerns the means used to materialize this method, such as electrical, magnetic, mechanical, and optical devices and the powering and packaging for them. Therefore the realization also includes the visual appearance, the industrial design of the computer."

Blaauw, 1990

After leaving IBM, Blaauw became a computer science professor in the Netherlands. He helped starting up the Technical University Twente and in 1981 the first computer science department started, which had some major subjects like "architecture" and "software". He retired in 1989 as professor emeritus with Universiteit Twente[5][6].


  1. Bloem, J. , "Van Rekenmachines naar Computerarchitectuur", Informatie, 02/2006.
  2. Visscher, Robert , "Fokker Friendship", Delta, vol. 38, issue 16, 05/2006.
  3. IBM Archives , IBM Archives: System/360 Announcement, , 1964  .
  4. Dijkstra, E.W. , E.W. Dijkstra Archive, , 2002  .
  5. Wikipedia , Gerrit Blaauw, , 2007  .
  6. Alberts, G., Blij, F. van der, Nuis, J. , Zij Mogen Uiteraard Daarbij De Zuivere Wiskunde Niet Verwaarloozen, , Amsterdam, Centrum voor Wiskunde en Informatica (CWI), 1987  .
Blaauw at ARRA IIBlaauw at ARRA IIBlaauw working at the ARRA II computer.