COMP 1321 Digital Infrastructure

1. COMP 1321 Digital Infrastructure Richard Henson University of Worcester September2018

2. Session 1(b): Digital Electronics • “Digital” requires two states (eg on/off) • Electrical Relays achieved that… hence Colossus • Electronic Valves achieved that quicker than relays… hence ENIAC • Both very large and cumbersome

3. US domination (and why…) • Late 1930s: Shannon dug up Boole’s work • found a good fit between “true/false”, electronic “on/off” valves, and binary numbers “0/1” • used Boolean Logic to create circuits wit predictable outcomes • very cumbersome and used a lot of energy • 1940s Europe devastated by war… • UK efforts… Bletchley Park • 1949: ENIAC First commercial computer • still used valves • very large and power hungry

4. The Transistor • Invented in 1947 (John Bardeen, Walter Brattain & William Shockley) • like a valve but low voltage, low energy • made Shannon’s vision based on Boole’s maths a reality • By 1960s: First minicomputer, the DEC PDP-1 (Program, Data, Processor)

5. UK computing in the 50s & 60s • The first “electronic brain” • http://www.bbc.co.uk/programmes/b069r3rt • The first electronic office: • http://www.bbc.co.uk/programmes/b069rvb4 • The first electronic lottery: • http://www.bbc.co.uk/programmes/b069rvb4

6. Programming • “A computer will do what you tell it to do, but that may be very different from what you had in mind.” • Joseph Weizenbaum

7. US domination of software & hardware development… • 1967: Relational database • 1969: Internet begins with 4 mainframes • 1971: Floppy disks • 1972: Intel, microprocessor • 1975: Apple, first microcomputer • 1976: Wang, first VDU

8. The First “Infrastructure” • Mainframes had no infrastructure • Separate area of their own… • Paper in… paper out! • VDU (1976 on…) allowed interaction with mainframe • multiuser systems • screens on people’s desks • communication protocols and cabling

9. Continued US Dmination… • 1976: Microsoft, computer language (BASIC) on a chip • 1981: IBM PC teamed up with Microsoft • first Desktop Operating system, MS-DOS, used in Business • Standalone, so no infrastructure…

10. Growth of Infrastructure… • Suddenly, a requirement for computers to communicate with other computers… • Hardware & protocols further refined • networks grew rapidly • mainframe-mainframe • PC-PC • even mainframe to PC! • PC emulated a terminal

11. Complexity of Infrastructure • From one monster computer in one place (1960s, early 70s)… • to PCs standalone and linked together (1980s) • client-end usable by non-specialists • then PCs linked direct to mainframes!

12. Networking: Integration of Telephone & Digital Infrastructures • Computing: OSI model (1978) • digital & encryptable • International Standard in 1984 • fast networks (10 Mb) • Telecoms… French domination • stubbornly analogue… • digital data had to be converted before/after transmission • slow 9 K, then 14.4K (wow!)

13. Integration of Telephone & Digital Infrastructures • Very slow evolution… • Speeded up thanks to the World Wide Web • Gradual evolution from analogue to digital telecoms (1990s/2000s) • ADSL and fast broadband possible (not rural areas…)

14. European Comeback? • 1988 onward: mobile phone • ARM CPU chip (Acorn) • low power… used in many devices • 1992: World Wide Web • EU research facility, CERN, under the Swiss Alps (Sir Tim Berners-Lee) • Late 1990s: Linux & Nokia

15. Still plenty of US domination… • i-player, i-phone, i-pad • Smart phone • Mobile apps • Tablets & e-books • Cloud computing • What next?… IoT, wetware?

16. What is Analogue? • The “real” world • Everything before Boole’s digital logic started to be used by computers… • including programs that were written solely to depict the real world • Data represents quantities exactly • e.g. the size of an electric voltage, the frequency of a signal, etc.

17. Analogue and Digital • Like computers… • most human inventions started out as analogue • Digital World ~ post-war human invention • based on George Boole’s maths… 100 years earlier • Discussion: • analogue or digital… which is best? Why?

18. Why Digital? • Fits Computer Data… based on binary 0 and 1 • two electrical states e.g. “on/off”, high/low voltage • worked for valves (ENIAC) • and transistors (DEC PDP) • became known as digital • Analogue remained for historical reasons… like degrees Fahrenheit?

19. Analogue to Digital • Computers just don’t do analogue! • Devices had to be invented to convent analogue data to digital • input devices • always an approximation (can be a very close approximation…)

20. Digital but not whole? • Any quantity can become digital! • (not just about whole numbers) • based on approximation… • Electrical on/off “state” represents data as (1s/0s) • presence/absence of an electric voltage • low voltage or higher voltage 0-2 volts = off, 3-5 volts = on • binary (off = 0, on = 1)

21. Digital multimeter • Ref: http://www.universal-radio.com/catalog/fm_txvrs/03850208.html

22. Analogue multimeter • Ref: http://www.kpsec.freeuk.com/multimtr.htm

23. Summary of Developments • Digital only possible thanks to George Boole (1850s, UK) • hardware began with Lord Babbage, but mechanical (1850s UK) • programming started with Lord Byron’s daughter, Ada Lovelace (1850s UK) • programmable analogue machines popular… • Electronics used Boole’s maths to predict output • Digital Computers created (Colossus/ENIAC) programmed in binary… (0/1) • world gradually became digital…