User:Chaosdruid/saved

From Disk storage
In the late 1940's information from the Manchester Mark 1 was stored externally onto a rotating drum, created in Manchester, England by Prof. F.C. Williams and J.C. West. The drum was coated with Nickel. The magnetic drum, or "wheel" as it was first called, had a set of parallel magnetic tracks arounfd the circumference of the drum forming a circle for each with a head for each of the tracks. Each of these tracks was capable of holding 2560 bits, or 2 pages. The drum had to be carefully synchronised with the main memory store of the computer and was capable of reading data twice as fast as it could write it.

Ferranti Ltd., who were developing their business machines from the work done in Manchester, took the prototype drum and improved it, making the reading heads and mechanical parts of the drum much more accurate and stable. This external unit was a 32 page capacity drum backing store, with 2 pages per track, and revolved once per 30 milliseconds.

The scientists in Manchester then adopted the improved version for use on the 'Mark 1 Final Specification' due to its better performance. Ferranti used this in the Ferranti Mark 1 commercially available computer produced at their works in Moston, Manchester. From the Ferranti Mark 1's sales book of the time : 'Storage capacity. High speed -- 10,000 binary digits on cathode ray tubes; equivalent to about 3,000 decimal digits. Magnetic drum -- 650,000 binary digits; equivalent to about 15,000 twelve-digit decimal numbers or 30,000 six-digit decimal numbers.'