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Noise is endemic – a fundamental property of electrical systems.
Thermal motion of electrons at any temp above 0K give rise to thermal noise – also many other sources.
Jean-Maurice-Émile Baudot 1845-1903
operators learned code
Keyboard non-trivial, operators had to work in time with synchroniser.
Telegraph printed on punched paper tape
5 bit code – 32 characters
Need 26 + 10 + punctuation
Use 2 modes to double length of set
Code used until 1940s for telegraph & telex links
Edison Effect –
soot particles from early lightbulbs blackened glass
tried putting electrode in bulb to attract particles
noticed that current flowed if wire was +ve wrt filament
didn’t follow up – patented as electrical indicator
John Fleming
US Patent 879532
Evolved from Crookes tube
Heater boils off electrons from cathode
electrons drawn from cathode towards 1st anode
through hole in anode forming beam
through 2nd anode
focussed into narrow beam be focussing coils
impinge upon fluorescent screen to produce light
control grid controls current in beam č light output
beam deflected across screen by deflection coils
The complexity for minimum component costs has increased at a rate of roughly a factor of two per year ... Certainly over the short term this rate can be expected to continue, if not to increase. Over the longer term, the rate of increase is a bit more uncertain, although there is no reason to believe it will not remain nearly constant for at least 10 years. That means by 1975, the number of components per integrated circuit for minimum cost will be 65,000. I believe that such a large circuit can be built on a single wafer.
Figure from Intel web site
Abu Yousuf Yaqub Ibn Ishaq al-Kindi was born at Kufa around 800 C.E
philosopher, mathematician, physicist, astronomer, physician, geographer
the philosopher of the Arabs “
241 books: Astronomy 16, Arithmetic 11, Geometry 32, Medicine 22,
Physics 12, Philosophy 22, Logic 9, Psychology 5, and Music 7
including “A manuscript of deciphering of Cryptographic Messages
Extensive publishing in Baghdad 100’s of bookshops
Study of works of Mohammed, linguistic & frequency analysis
Also sometimes other characters:
Carol, Dave – also in on conversation
Marvin – a malicious evesdropper
Isaac – an ISP
Plod – a law enforcer
Edward Lorenz – US mathematician, weather forecaster for US Army Air coprs during WWI. Made mathematical models of weather systems, noticed ‘unpredicatable behaviour. wrote a set of equations for convection to explain weather pattern. He made the equations as simple as possible, but left in non-linear terms.
Certain non-linear systems that show apparently random motion show a strange form of order when plotted in a suitable phase space - the motion never repeats itself, but is confined to a fixed region of space - a strange attractor