COMP 1321 Digital Infrastructure Richard Henson University of Worcester September 2013
What is a computer? n n In small groups… Four attributes of a computer… What is it? What does it do? 10 minutes
Are these computers? n n AbacusTypewriter Bathroom scales Car speedometer Thermostat Stonehenge Pocket calculator Person DVD playerMicrophone
History of Computing (Origins) n n 3400 BC: counting in tens (Egypt) 2600 BC: Abacus (China) BC: Stonehenge completed 260 BC: base-20 counting – including zero (Maya – Central America)
Abacus n n Ref: h/stage1/assign2/pre20th.htm h/stage1/assign2/pre20th.htm
Stonehenge n n Ref:
History of Computing (Europe) n n 967 AD: Zero in the eastern hemisphere (Muhammad Bin Ahmad) n n Around 1500: Design of mechanical calculator (Leonardo da Vinci) n n 1614: Logarithms (John Napier) n n 1621: Slide rule (Edmund Gunter, William Oughtred)
Slide rules n n Ref:
History of Computing (Europeans – continued) n n 1642: Adding machine (Blaise Pascal) 1679: Binary arithmetic (Gottfried Leibnitz) 1820s and 1830s: Charles Babbage’s Difference Engine and Analytical Engine 1840s George Boole: Boolean Algebra – algebra using just 0 and 1
Babbage n n Ref:
Boole: inventor of “digital” n n Ref:
European Domination (mostly British) n n 1843: The idea of Computer Programming (Ada Lovelace (Byron)) n n 1904: Vacuum tubes (“valves”) birth of electronics (John – not Alexander - Fleming) n n The Second World War 1936: Programmable computer (Konrad Zuse, Germany) 1943: Colossus – won the war?
Colossus – what’s that! n n Top secret code breaker … 9000 people worked at Bletchley Park during ww2… above, two of them… n n n n
Post-war: US domination n n 1947: Transistors (John Bardeen, Walter Brattain & William Shockley) n n 1949: ENIAC First commercial computer n n 1960s: First minicomputer, the DEC PDP-1 (Program, Data, Processor) n n 1969: Internet begins with 4 mainframes n n 1971:Floppy disks (IBM: Alan Shugart et al.) n n 1981: IBM PC launched with Microsoft Operating system, MS-DOS
Programming n n “A computer will do what you tell it to do, but that may be very different from what you had in mind.” Joseph Weizenbaum
Development of Infrastructure n n Input-output extended through dumb terminals (Wang, 1970s) n n Linked together Peer-peer networks (Internet…) n n Networks evolve into client-server (1980s) client-end usable by non-specialists
European Comeback? n n 1988: ARM CPU chip (Acorn) used in many mobile phones n n 1991: World Wide Web founded at EU research facility, CERN, under the Swiss Alps (Sir Tim Berners-Lee)
Integration of Telephone and Digital Infrastructures n n OSI model (1978) International Standard in 1984 n n European (French) domination stubbornly analogue… digital data had to be converted before transmission very slow… n n Gradual evolution to digital telecoms (1990s/2000s) ADSL and fast broadband (not rural areas…)
More US domination n n Mobile phone n n i-player, i-phone, i-pad n n Smart phone n n Mobile apps n n Tablets & e-books n n Cloud computing n n What next?…
This? n n The credit card sized Raspberry Pi… designed in UK, and now manufactured in UK! available for resale at less than £30
Digits? n n Odd word… used to mean fingers and toes n n Therefore about whole numbers of things n n Gave birth to a hugely influential adjective… n n DIGITAL
Digital but not whole? n n Now any quantity can become digital! based on approximation… n n Use “state” (on or off) to represent data presence/absence of an electric voltage low voltage or higher voltage 0-2 volts = off, 3-5 volts = on binary (off = 0, on = 1) n n numbers electrical “square wave” pulses great for working with transistors…
Digital multimeter n n Ref: radio.com/catalog/fm_txvrs/ htmlhttp:// radio.com/catalog/fm_txvrs/ html
Analogue (as it really is…) n n Uses physical entities to represent data exactly e.g. the size of an electric voltage, the frequency of a signal, etc.
Analogue multimeter n n Ref:
Analogue and Digital n n The real world has always been analogue… n n Digital World = post-war human invention n n Discussion: analogue or digital… which is best
Summary n n No fuzziness in digital: exact value n n No fractions in digital: precision of value limited to last digit n n Electronics easier with digital n n Precision of instruction is crucial: n n Computers don’t need tea-breaks (!)