The Williams tube or (more accurately) the Williams-Kilburn tube (after Freddie Williams and coworker Tom Kilburn), developed about 1946 or 1947, was a cathode ray tube used to store electronic data.
When a dot is drawn on a cathode ray tube, the spot lasts for a time that depends on the type of phosphor used in the tube. Another Williams tube side effect is that the area around this dot is slightly changed in electrical charge. By measuring the charge at that spot you have a simple form of memory that lasts for a time depending on the type of phosphor used. Because the charge gradually leaked off, it was necessary to scan the tube periodically and rewrite every dot (similar to the refresh cycles of DRAM in modern systems).
Developed at the University of Manchester in England, it provided the medium on which the first ever electronically stored-memory program was written in the Manchester Mark I computer. Tom Kilburn wrote a 17-line program to calculate the highest factor of a number.
The Williams tube was regarded as extremely unreliable, and touchy. Most working installations had to be "tuned" by hand. In contrast, delay line memory was slower, but quite reliable. This is why delay lines were used in most machines that were regarded as successful.
External links
- The Williams Tube
Electronics Topics
The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is part of the fields of electronic engineering, and the hardware design side of computer engineering. The study of new semiconductor devices and their technology is sometimes considered as a branch of physics.
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