1. COMP 1321 Digital Infrastructure Richard Henson University of Worcester September 2012

2. What is a computer? n n In small groups…   Four attributes of a computer…   What is it?   What does it do?   10 minutes

3. Are these computers? n n AbacusTypewriter Bathroom scales Car speedometer Thermostat Stonehenge Pocket calculator Person DVD playerMicrophone

4. History of Computing (Origins) n n 3400 BC: counting in tens (Egypt) 2600 BC: Abacus (China) 1900-1600 BC: Stonehenge completed 260 BC: base-20 counting – including zero (Maya – Central America)

5. Abacus n n Ref: http://www.tased.edu.au/schools/rokebyh/curric/infotec h/stage1/assign2/pre20th.htm http://www.tased.edu.au/schools/rokebyh/curric/infotec h/stage1/assign2/pre20th.htm

6. Stonehenge n n Ref: http://www.astro.virginia.edu/class/courses.htmlhttp://www.astro.virginia.edu/class/courses.html

7. 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)

8. Slide rules n n Ref: http://osaki.cool.ne.jp/other/other/sliderule/sliderule.htmlhttp://osaki.cool.ne.jp/other/other/sliderule/sliderule.html

9. 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

10. Babbage n n Ref: http://w1.131.telia.com/~u13101111/merschwib.htmlhttp://w1.131.telia.com/~u13101111/merschwib.html

11. Boole: inventor of “digital” n n Ref: http://buttrysymicaela.blogspot.co.uk/2010/06/george-boole.htmlhttp://buttrysymicaela.blogspot.co.uk/2010/06/george-boole.html

12. 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?

13. Colossus – what’s that! n n Top secret code breaker … 9000 people worked at Bletchley Park during ww2… here are two of them…

14. 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

15. 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

16. 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)

17. 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…)

18. 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 Cloud computing n n What next?…

19. This? n n The credit card sized Raspberry Pi…   designed in UK, and now manufactured in UK!   available for resale at less than £30

20. Digital? n n 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…

21. Digits n n from http://www.dribbleglass.com/Toes/uglyt oes-2.htm http://www.dribbleglass.com/Toes/uglyt oes-2.htm

22. Digital multimeter n n Ref: http://www.universal- radio.com/catalog/fm_txvrs/03850208.ht mlhttp://www.universal- radio.com/catalog/fm_txvrs/03850208.ht ml

23. Analogue n n Uses physical entities to represent data e.g. the size of an electric voltage, the frequency of a signal, etc.

24. Analogue multimeter n n Ref: http://www.kpsec.freeuk.com/ multimtr.htm

25. 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

26. 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: “A computer will do what you tell it to do, but that may be very different from what you had in mind.” (Joseph Weizenbaum) n n Computers don’t need tea-breaks (!)