http://news.bbc.co.uk/1/hi/technology/7465115.stm One tonne 'Baby' marks its birth By Jonathan Fildes Science and technology reporter, BBC News Baby project team The four remaining members of the Baby team will be honoured in Manchester Sixty years ago the "modern computer" was born in a lab in Manchester. The Small Scale Experimental Machine, or "Baby", was the first to contain memory which could store a program. The room-sized computer's ability to carry out different tasks - without having to be rebuilt - has led some to describe it as the "first modern PC". <snip>

Electrical charges on the screen of the CRT were used to represent binary information. A positive charge represented a one and a negative charge a zero. A metal grid attached to the screen read the different charges. A graphical representation - dashes for a one and dots for a zero - was displayed on a second CRT wired in parallel to the memory device.