The ARRA was the first Dutch computer, and was built from relay

Relay

A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...

s for the Dutch Mathematical Centre (Dutch: Mathematisch Centrum), which later became the Centrum Wiskunde & Informatica (CWI).

It was designed and built by Carel Scholten and Bram Loopstra, and was finished in 1952. Because of reliability problems it was soon taken out of commission, and "updated" to the ARRA II, which actually was a completely new design.

See also

Other computers designed and built at the Mathematical Centre:

• ARRA II (computer)
• FERTA (computer)
• ARMAC (computer)

Other very early Dutch computers:

• P3 (computer)
• PASCAL (computer)
• PETER (computer)
• PTERA (computer)
• STEVIN (computer)
• Testudo (computer)
• X1 (computer)
  Electrologica X1
  The Electrologica X1 was a digital computer designed and manufactured in the Netherlands from 1958 to 1965. About thirty were produced and sold in the Netherlands and abroad....
  
  
• X2 (computer)
• X4 (computer)
• X8 (computer)
  Electrologica X8
  The Electrologica X8 was a digital computer designed as a successor to the Electrologica X1 and manufactured in the Netherlands by Electrologica NV from 1965 onwards....
  
  
• ZEBRA (computer)
  ZEBRA (computer)
  The ZEBRA was one of the first computers to be designed in the Netherlands, and one of the first Dutch computers to be commercially available...
  
  
• ZERO (computer)