Workshop 7 Connected Computers 1.How to make reliable systems from unreliable parts? 2.Societal impact of computers? 3.Collective intelligence and the World Wide Web?

Licklider at MIT  1942 Harvard Psycho-Acoustic Lab  1950 MIT started Lincoln Labs – Lick headed human engineering group  Lincoln Labs built the monster Sage computer to monitor early warning radar. The visual information was displayed on screens leaving human operators to interpret it. IBM Sage Computer Ad, 1960 (3 minutes) cacheIBM Sage Computer Ad, 1960 cache  1960 Lick published "Man-Computer Symbiosis“ (full text) “Men will set the goals, formulate the hypotheses, determine the criteria, and perform the evaluations. Computing machines will do the routinizable work …”"Man-Computer Symbiosis“ Katie Hafner & Matthew Leon, Where wizards stay up late – good source on Licklider

Intergalactic computer network  1962 Licklider conceived a global computer network at Bolt, Beranek and Newman  "Topics for Discussion at the Forthcoming Meeting, Memorandum For: Members and Affiliates of the Intergalactic Computer Network“ 1963 "Topics for Discussion at the Forthcoming Meeting, Memorandum For: Members and Affiliates of the Intergalactic Computer Network“  Consider the situation in which several different centers are netted together, each center being highly individualistic and having its own special language and its own special way of doing things. Is it not desirable, or even necessary for all the centers to agree upon some language or, at least, upon some conventions for asking such questions as “What language do you speak?” At this extreme, the problem is essentially the one discussed by science fiction writers: “how do you get communications started among totally uncorrelated “sapient” beings?” …

Claude Shannon – Information Theory  1940 Master’s thesis at MIT: A Symbolic Analysis of Relay and Switching Circuits – Boolean algebra could be used to design digital circuits  1943 Briefly worked with Alan Turing on cryptography  1948 A Mathematical Theory of Communication – Shannon proposed encoding messages in a way similar to telegraphy, i.e. frequent letters such as ‘e’ and ‘s’ are encoded by short sequences, infrequent ones suck as ‘x’ by long ones. Given transmission line characteristics, it is possible to assign an upward limit to the information that can be carried. James Gleick, The Information Good source for Shannon Tech Icons: Claude Shannon Tech Icons: Claude Shannon (8 minutes) cachecache Claude Shannon - Father of the Information Age (30 minutes) cacheFather of the Information Agecache

Origins of the Internet – The Arpanet  ARPA (defense dept.) was supporting research at diverse campuses  The projects required extensive computer resources  The computers systems differed and could not communicate with each other  Research was often duplicated  Nuclear annihilation threat  With communications down countries could not respond in a measured way  This favored pre-emptive attack  Robust communications would give more time for a deliberate response  ARPAnet - the team behind the internet (6 minutes) cache ARPAnet - the team behind the internet cache

Network topology  The balls are nodes (computers)  The lines are links (wires)  Which topologies have a single point of failure? (node or link)  Which topology is most likely to survive an attack?

Packet Switching  Goal: Remove need for a dedicated (phone line?) circuit  Break a message into small packets  Label each packet with destination and source addresses + packet number + …  Packets may be routed differently to balance network traffic  At destination message is reassembled  Missing or damaged packets are resent  Developed independently by Paul Baran at the RAND Corporation and Donald Davies in the UK How does a packet travel the network? by Susana RiosHow does a packet travel the network? by Susana Rios (3 minutes) cachecache Understanding the OSI Reference Model Understanding the OSI Reference Model (10 minutes – gets technical) cache cache High Tech Heroes #32: Paul Baran High Tech Heroes #32: Paul Baran (28 minutes) cache cache

The World Wide Web  Tim Berners-Lee: The next Web of open, linked data (17 minutes ) cache Tim Berners-Lee: The next Web of open, linked data cache  Marc Andreessen On The Internet's Early Days – Talks about developing MOSAIC browser at Univ. Of Illinois (4 minutes) cache Marc Andreessen On The Internet's Early Days cache From The Guardian

Search Engines  Alta Vista Launched 1995 created by DEC, subsumed into YAHOO and shut down in 2013  Alta Vista ad featuring Garry Kasparov cache Alta Vista ad featuring Garry Kasparovcache  Terry Winograd  Thesis advisor Seymour Papert  Spcialty: human-computer interaction HCI  At Stanford had students Larry Page & Sergei Brin  How Search Engines Work (6 minutes) cache How Search Engines Work) cache  Chart showing How Google WorksHow Google Works

Open Source & Free Software  Feedback loops – Cybernetics  1983 Richard Stallman launched GNU EMACS  Free software, free society: Richard Stallman at TEDxGeneva 2014 (13 minutes) cache Free software, free societycache  Linus Torvalds: 2014 Computer Pioneer Award (9 minutes) cache Linus Torvaldscache

Wikipedia  TED Jimmy Wales The Birth of Wikipedia (20 minutes) cache The Birth of Wikipediacache

Social Networking  2003 MySpace  2004 Facebook The Illustrated Story of Facebook (2 minutes) cacheThe Illustrated Story of Facebookcache  An Interview with Mark Zuckerberg (9 minutes) An Interview with Mark Zuckerberg

Further Reading  Hafner, Katie, Where Wizards Stay Up Late: The Origins of The Internet, Simon & Shuster,  Berners-Lee, Tim, Weaving the Web: The Original Design and Ultimate Destiny of the World Wide Web, Harper-Collins, 2000.