COMP 1321 Digital Infrastructure Richard Henson University of Worcester September 2018

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

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

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)

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:

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

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

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

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…

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

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!

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!)

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…)

European Comeback? 1988 onward: mobile phone 1992: World Wide Web 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

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

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.

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?

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?

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…)

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)

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

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

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…