Midterm Exam Review PDF

Lecture: Chapter 1 Computing Before Computers  Charles Babbage (1791-1871)  19th-century mathematics professor at Cambridge  Difference Engine (1821)  Required 25,000 parts, weighed 15 tons  Never finished it  The Analytical Engine (1843)  Mother of all c...

Lecture: Chapter 1 Computing Before Computers  Charles Babbage (1791-1871)  19th-century mathematics professor at Cambridge  Difference Engine (1821)  Required 25,000 parts, weighed 15 tons  Never finished it  The Analytical Engine (1843)  Mother of all computers, conceived of by Charles Babbage  Also, never finished  Could (theoretically) be programmed with punched cards  Could carry out any calculation to 20 digits of accuracy Computing Before Computers  Augusta Ada King, Countess of Lovelace  Interpreter and promoter of Babbage’s visionary work  Wrote a plan for using the Analytical Engine to calculate Bernoulli sequences  Making her the first computer programmer Computers in Perspective: An Evolving Idea (continued) At about the same time, the British government was assembling a top-secret team of mathematicians and engineers to crack Nazi military codes 1943: The team, led by mathematician Alan Turing and others, completed Colossus, considered by many to be the first electronic digital computer  Turing was key in breaking Enigma – the German military’s chief cipher machine. Turing is also known for the Turing Test – a basic test for artificial intelligence. Computers in Perspective: An Evolving Idea (continued)  John Mauchly and J. Presper Eckert helped the U.S. effort in World War II by constructing a machine to calculate trajectory tables for new guns called ENIAC (Electronic Numerical Integrator and Computer)  After the war, Mauchly and Eckert started a private company called Sperry and created UNIVAC I, the first general-purpose commercial computer Admiral Grace Hopper  Invented the compiler, ca 1952  Created one of the first programming languages, COBOL  Coined the term “debug”  Referred to an actual moth stuck in the Harvard Mark II computer. Computers in Perspective: An Evolving Idea (continued) Evolution and Acceleration Vacuum tubes were used in early computers Transistors replaced vacuum tubes starting in 1956 By the mid-1960s transistors were replaced by integrated circuits, commonly known as silicon chips Computers Today: A Brief Taxonomy Personal computers and workstations (cont.)  Laptop, or notebook, computers are personal computers designed with portability in mind Some components are left off to help keep size and weight down Relatively fragile Expensive to upgrade or repair. Key term: Proprietary hardware Computers Today: A Brief Taxonomy Virtual Computers A Personal Computer can run multiple operating systems simultaneously VMWare Fusion Parallels VirtualBox (free!) Large servers can virtualize thousands of machines Freeware and Open Source Freeware ◦ Actually Free – no strings attached ◦ Often unsophisticated, but sometimes what you need ◦ Often quite sophisticated: Firefox, VLC Media Player, etc.  OpenSource: Not just free software, free source code ◦ Free download ◦ Free to modify ◦ Free to improve Free Books Project Gutenberg – www.gutenberg.org ◦ Repository of 60,000+ free texts  Public domain  Out of copyright ◦ Mostly an English-language phenomenon  Many translated works  But the translation has to be in the public domain ◦ Can be downloaded directly to most computers and mobile devices. A Bit About Bits Bits, Bytes, and Buzzwords Bit-related terminology – Byte = 8 bits – Kilobyte (KB) = 1 Thousand Bytes – Megabytes (MB) = 1 Million Bytes – Gigabytes (GB) = 1 Billion Bytes – Terabytes (TB) = 1 Trillion Bytes – Petabytes (PB) = 1 Quadrillion Bytes GHz  Speed often expressed in megahertz (MHz) or gigahertz (GHz) ◦ Typical Desktop PC processors: 1.5 GHz – 3.0 GHz per core ◦ Modern desktops typically have dual-core or quad- core processors  Analogous to clock ticks  1 GHz - capable of handling 1 billion machine cycles per second  Note: ◦ Intel (the largest CPU manufacturer) uses the GHz rating, ◦ AMD (the primary non-Intel CPU manufacturer) used a different rating system for years, but now uses GHz as well. Price of a Gigabyte of storage 1984 - $500,000 1989 – $80,000 1994 - $3,000 2023 - 1¢ Moore’s Law  Gordon Moore’s real version: ◦ The number of transistors that can be inexpensively placed on an integrated circuit doubles every two years.  Popular variants include: ◦ Transistors will double every 18 months. ◦ Processing speed and storage capacity will double every 18 months.  Frequently ignored addendum (by Gordon Moore): ◦ The exponential growth can't continue forever. Miniaturization will eventually approach atomic sizes.  Inany case, it’s a description of a modern trend, not a true physical law. The Computer’s Memory  RAM (random access memory)  Used to store program instructions and data temporarily  Unique addresses and data can be stored in any location  Can quickly retrieve information  Will not remain if power goes off (volatile) Chapter 2 A Bit About Bits (continued) Using two symbols all numbers can be represented or calculated A calculator translates the touch on the numeric keypad into series of 0s and 1s  Each number then is looked at as a component of its positional values (each a power of 2)  19 will be represented as 00010011 Number systems 1. Hexadecimal Number: base 16  Alternative representation to binary  0123456789ABCDEF Sli de 17 A Bit About Bits (continued) Bits as codes ASCII  The most widely used code  An abbreviation of American Standard Code for Information Interchange Unicode  A coding scheme supporting 65,000 unique characters  ALU – Arithmetic/logic unit electroniccircuitry executes arithmetic and logical operations ◦ arithmetic operations  addition  subtraction  multiplication  division  Input devices – dvorak keyboard developed 1936 to improve efficiency hands don't have to move as much  Input devices – touch  screen Touch screens ◦ Resistive screens: edges emit horizontal and vertical light beams ◦ Capacitive screens create electromagnetic field, blocked by the electromagnetic field of your skin.  Also allows for multi-touch input ◦ Input and output from the same device ◦ Good for systems where a keyboard would be cumbersome ◦ Now common on smartphones, tablets, some laptops  Accelerometer Detects vertical or lateral motion, converts to a digital signal. Smartphones Nintendo Wii-mote Monome  Optical input methods Bar codes:  Universal Product Code (UPC) ◦ pattern of vertical marks  Bar code reader ◦ reads code horizontally  QR Codes and readers ◦ Code stored horizontally and vertically ◦ Can store ~4000 alphanumeric characters ◦ Typically used for web addresses Optical recognition – other ways OMR - optical mark recognition ◦ machine senses marks on paper ◦ fill-in sheets ◦ Pink scantron OCR - optical character recognition ◦ recognizes individual letters of text otherwise just copying dots ◦ MICR fonts  readable by humans and machines  typeface developed by American National Standards Institute Magnetic Card Readers and RFID transponders RFID = Radio Frequency Identification Commonly used in employee/Student ID badges, theft prevention systems, many others Briefly used in credit cards, now rare Potential for misuse, invasion of Printer Output Non-impact printers Laser printers Laser beam reflected off a rotating drum to create patterns of electrical charges These electrical charges attract toner, a fine colored powder, which is then heated to fuse to the paper Faster and more expensive than inkjet printers High-resolution print output Inkjet printers Sprays ink onto paper to produce printed text and graphic images Prints fewer pages/minute than laser printer Higher-quality color for less $ than a color laser printer Liquid ink creates more vivid and accurate color than combinations of different colored toner  Secondary Storage Devices Magnetic Disks Random data access Secondary Storage Floppy disks Provide inexpensive, portable storage Hold too little data for modern purposes Hard disks Non-removable, rigid disks that spin continuously and rapidly US Copyright Law US Constitution, Article I, Section 8, gives Congress the power to enact statutes: ◦ “To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.” ◦ Copyrights – ideas, creative works  70 years + life of author (or up to 120 years for works of corporate authorship)  (Was 50 years + life of author, until Bono Act of 1998) ◦ Patents - inventions Sony vs. Universal Studios Landmark 1984 copyright case The Motion Picture industry tried to prevent the sale of video recording technology for home use. ◦ Arguments:  Home recording of televised movies would hurt box office returns and ad revenue from future broadcasts.  Claimed Sony should be liable for potential misuse by its products’owners. Music – Jammie Thomas Case October 4, 2007: Capital Records et al v. Jammie Thomas  Jammie Thomas sued for $222,000 for making 24 songs available for download on Kazaa ◦ $9,250 per song. ◦ The plaintiff was unable to prove that anyone had downloaded the songs, only that they were made available.  Sony’s position in the trial: ◦ “When an individual makes a copy of a song for himself, I suppose we can say he stole a song. Making ‘a copy’ of a purchased song is just a nice way of saying ‘steals just one copy’.” -Jennifer Pariser, the head of litigation for Sony BMG  Retrial ◦ The trial judge vacated the award and ordered a retrial, under doubt that simply making copyrighted material DMCA Safe Harbor provisions Allow for free speech and free exchange of information over the internet ◦ While still providing copyright holders a method to remove infringing content Sites that host or enable user-shared content are not immediately liable for infringing material ◦ Copyright holders can contact sites and file takedown notices ◦ If the hosts don’t remove the infringing Aaron Swartz  Helped develop: ◦ RSS (Really Simple Syndication), Reddit, Creative Commons  Founded Demand Progress ◦ Instrumental in halting SOPA  Legal troubles: ◦ PACER in 2008  Public Access to Court Electronic Records  By charging 8 cents a page for accessing public records, court system made roughly $100 million a year ◦ JSTOR in 2010  Faced 50+ years in Federal Prison for Wire Fraud and violations of the Computer Fraud and Abuse Act.  Committed suicide, January 2013, two days after a rejected settlement offer. Fair Use Generally, exceptions are made for duplicating copyrighted content: ◦ For criticism or commentary  This includes parody, even for commercial gain. ◦ For teaching, scholarship, or research These exceptions are not absolute  Courts can consider the amount of the work you duplicate, and the effect on the use’s effect on its market. Fair Use is a defense you can bring up in court.  But it is not a guarantee that you cannot be sued in the first place. Grey Areas: Abandonware The product has been off the shelves for years. The company that made it has gone out of business. The computer system it runs on has been obsolete since 1991. Who is this hurting? ◦ Typically, no one. ◦ But it can discourage nostalgia releases of old software (mostly games). ◦ Rights purchased by other companies.  e.g. mobile app publishers buy rights to older games