Dekatron Memory Unit (The WITCH)

Ted Cooke-Yarborough1951

The National Museum of Computing

The National Museum of Computing
MILTON KEYNES, United Kingdom

Memory is the part of a computer that stores data, programs and instructions that are currently in use. Primary memory is located inside the computer. The WITCH has ⅓ Kb primary memory (RAM), made up of 828 Dekatrons in nine separate units. A type of valve, a dekatron is is a small counting tube that contains neon or helium to create a glowing charge. Each dekatron is capable of storing a single decimal digit. The WITCH is one of the only computers in the world that has a memory that can be read visually, thanks to its bulk use of Dekatrons.


  • Title: Dekatron Memory Unit (The WITCH)
  • Creator: Ted Cooke-Yarborough
  • Date Created: 1951
  • Location: The National Museum of Computing (Buckinghamshire, UK)
  • Location Created: Harwell Atomic Energy Research Establishment (Oxfordshire, UK)

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