Colossus computer
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Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves to perform Boolean and counting operations. Colossus is thus regarded as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program.
A Colossus Mark 2 computer being operated by Wrens. The slanted control panel on the left was used to set the "pin" (or "cam") patterns of the Lorenz. The "bedstead" paper tape transport is on the right.
A Lorenz SZ42 cipher machine with its covers removed at The National Museum of Computing on Bletchley Park
The Lorenz SZ machines had 12 wheels, each with a different number of cams (or "pins"). Wheel number 1 2 3 4 5 6 7 8 9 10 11 12 BP wheel name ψ1 ψ2 ψ3 ψ4 ψ5 μ37 μ61 χ1 χ2 χ3 χ4 χ5 Number of cams (pins) 43 47 51 53 59 37 61 41 31 29 26 23
Cams on wheels 9 and 10 showing their raised (active) and lowered (inactive) positions. An active cam reversed the value of a bit (0→1 and 1→0).
General Post Office
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The General Post Office (GPO) was the state postal system and telecommunications carrier of the United Kingdom until 1969. Established in England in the 17th century, the GPO was a state monopoly covering the dispatch of items from a specific sender to a specific receiver ; it was overseen by a Government minister, the Postmaster General. Over time its remit was extended to Scotland and Ireland, and across parts of the British Empire.
'The Post Horse' (from The Life of a Racehorse, or The High-Mettled Racer) by Thomas Rowlandson, 1789.
North Country Mails at the Peacock, Islington by James Pollard (1821).
Telegraph sent in 1907
Telegraphic Operating Room in the Central Telegraph Office (GPO West), St Martin's Le Grand, London.