Harwell CADET facts for kids
| Manufacturer | AERE |
|---|---|
| Release date | February 1955 |
| Memory | 64k |
| Predecessor | Harwell Dekatron Computer |
The Harwell CADET was a very important early computer. It was the first computer in Europe to use only transistors. Some people even think it might have been the first in the whole world!
Scientists at the Atomic Energy Research Establishment (AERE) in Harwell, UK built it. They had already made another computer called the Harwell Dekatron Computer in 1951. That computer used electronics for math and memory, but other parts still used older technology like relays.
By 1953, the AERE needed a more powerful computer. Sir John Cockcroft, the director, encouraged his team to build a new one. This new computer would use only transistors.
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Building the CADET Computer
A scientist named E. H. Cooke-Yarborough led the design of the CADET. He based the computer around a special magnetic drum memory. This drum could store 64 kilobytes of information. That's 65,536 bytes!
His team had already figured out how to use transistors with a smaller magnetic drum. The CADET computer ran at a slow speed of 58 kilohertz. This slow speed meant they didn't need to use old-fashioned valves for the clock. Even though it was slow, it could add eight numbers at the same time. This made it faster for some tasks.
What Does CADET Mean?
The computer was named CADET. This name stands for "Transistor Electronic Digital Automatic Computer." It's a bit of a funny name because the letters are backward!
The CADET ran its first test program in February 1955. It used 324 special point-contact transistors. These were the only type of transistors available in large numbers back then. It also used 76 junction transistors. These were better for reading data from the drum.
The CADET was built using simple circuit boards. It was never put into a fancy case. It stayed in its original "breadboard" form.
CADET in Action
From August 1956, the CADET started working regularly. It often ran for very long periods, sometimes for 80 hours or more without stopping!
Cooke-Yarborough thought the CADET was probably the second fully transistorised computer to be used. He believed an IBM machine was first. Other early computers like the Manchester University Transistor Computer and the Bell Laboratories TRADIC also used transistors. However, they still needed some old-fashioned vacuum tubes for power. This meant they weren't fully transistorised like the CADET.
In April 1955, IBM announced their IBM 608 transistor calculator. They said it was the first all solid-state computer sold to businesses. It might have been shown in October 1954, before the CADET.
Retirement of the CADET
By 1956, scientists at AERE needed even more computing power. Brian Flowers, who led the theoretical physics division, decided the CADET wasn't enough. He ordered a new, more powerful computer called the Ferranti Mercury.
In 1958, the new Mercury computer started working at AERE. The CADET continued to operate alongside it for two more years. After four years of helping scientists, the Harwell CADET was finally retired.
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