- Slides: 23
COMP 1321 Digital Infrastructure Richard Henson University of Worcester September 2018
Session 1(b): Digital Electronics n “Digital” requires two states (eg on/off) ØElectrical Relays achieved that… hence Colossus ØElectronic Valves achieved that quicker than relays… hence ENIAC n Both very large and cumbersome
US domination (and why…) n Late 1930 s: Shannon dug up Boole’s work Ø found a good fit between “true/false”, electronic “on/off” valves, and binary numbers “ 0/1” Ø used Boolean Logic to create circuits wit predictable outcomes Ø very cumbersome and used a lot of energy n 1940 s Europe devastated by war… Ø UK efforts… Bletchley Park n 1949: ENIAC First commercial computer Ø still used valves Ø very large and power hungry
The Transistor n Invented in 1947 (John Bardeen, Walter Brattain & William Shockley) Ø like a valve but low voltage, low energy Ø made Shannon’s vision based on Boole’s maths a reality n By 1960 s: First minicomputer, the DEC PDP 1 (Program, Data, Processor)
UK computing in the 50 s & 60 s n The first “electronic brain” Øhttp: //www. bbc. co. uk/programmes/b 069 r 3 rt n The first electronic office: Øhttp: //www. bbc. co. uk/programmes/b 069 rvb 4 n The first electronic lottery: Øhttp: //www. bbc. co. uk/programmes/b 069 rvb 4
Programming n “A computer will do what you tell it to do, but that may be very different from what you had in mind. ” ØJoseph Weizenbaum
US domination of software & hardware development… n n n 1967: Relational database 1969: Internet begins with 4 mainframes 1971: Floppy disks 1972: Intel, microprocessor 1975: Apple, first microcomputer 1976: Wang, first VDU
The First “Infrastructure” n Mainframes had no infrastructure ØSeparate area of their own… ØPaper in… paper out! n VDU (1976 on…) allowed interaction with mainframe Ø multiuser systems Ø screens on people’s desks Ø communication protocols and cabling
Continued US Dmination… 1976: Microsoft, computer language (BASIC) on a chip n 1981: IBM PC teamed up with Microsoft n Øfirst Desktop Operating system, MS-DOS, used in Business ØStandalone, so no infrastructure…
Growth of Infrastructure… n Suddenly, a requirement for computers to communicate with other computers… ØHardware & protocols further refined Ønetworks grew rapidly » mainframe-mainframe » PC-PC » even mainframe to PC! n PC emulated a terminal
Complexity of Infrastructure n From one monster computer in one place (1960 s, early 70 s)… Øto PCs standalone and linked together (1980 s) » client-end usable by non-specialists Øthen PCs linked direct to mainframes!
Networking: Integration of Telephone & Digital Infrastructures n Computing: OSI model (1978) Ø digital & encryptable Ø International Standard in 1984 Ø fast networks (10 Mb) n Telecoms… French domination Ø stubbornly analogue… Ø digital data had to be converted before/after transmission Ø slow 9 K, then 14. 4 K (wow!)
Integration of Telephone & Digital Infrastructures n Very slow evolution… Ø Speeded up thanks to the World Wide Web n Gradual evolution from analogue to digital telecoms (1990 s/2000 s) Ø ADSL and fast broadband possible (not rural areas…)
European Comeback? n 1988 onward: mobile phone ØARM CPU chip (Acorn) Ølow power… used in many devices n 1992: World Wide Web ØEU research facility, CERN, under the Swiss Alps (Sir Tim Berners-Lee) n Late 1990 s: Linux & Nokia
Still plenty of US domination… n n n i-player, i-phone, i-pad Smart phone Mobile apps Tablets & e-books Cloud computing What next? … Io. T, wetware?
What is Analogue? The “real” world n Everything before Boole’s digital logic started to be used by computers… n Øincluding programs that were written solely to depict the real world n Data represents quantities exactly Øe. g. the size of an electric voltage, the frequency of a signal, etc.
Analogue and Digital n Like computers… Ømost human inventions started out as analogue n Digital World ~ post-war human invention Ø based on George Boole’s maths… 100 years earlier n Discussion: Øanalogue or digital… which is best? Why?
Why Digital? n Fits Computer Data… based on binary 0 and 1 Øtwo electrical states e. g. “on/off”, high/low voltage » worked for valves (ENIAC) » and transistors (DEC PDP) Øbecame known as digital n Analogue remained for historical reasons… like degrees Fahrenheit?
Analogue to Digital Computers just don’t do analogue! n Devices had to be invented to convent analogue data to digital n Øinput devices Øalways an approximation (can be a very close approximation…)
Digital but not whole? n Any quantity can become digital! Ø (not just about whole numbers) Ø based on approximation… n Electrical on/off “state” represents data as (1 s/0 s) Ø presence/absence of an electric voltage Ø low voltage or higher voltage 0 -2 volts = off, 3 -5 volts = on Ø binary (off = 0, on = 1)
Digital multimeter n Ref: http: //www. universalradio. com/catalog/fm_txvrs/03850208. html
Analogue multimeter n Ref: http: //www. kpsec. freeuk. com/multimtr. htm
Summary of Developments n Digital only possible thanks to George Boole (1850 s, UK) Ø hardware began with Lord Babbage, but mechanical (1850 s UK) Ø programming started with Lord Byron’s daughter, Ada Lovelace (1850 s UK) Ø programmable analogue machines popular… n Electronics used Boole’s maths to predict output Ø Digital Computers created (Colossus/ENIAC) programmed in binary… (0/1) Ø world gradually became digital…