Computer Science 1026 Topic 1.docx

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Computer Science
Computer Science 1026A/B
Brian Langen

Topic 1: Introduction to Computer Science and Computing Introduction  Computers are everywhere around us  Computers cannot be given the quality of „smartness‟ because it does not think. It is a simple utensil that provides certain output for input. Even compared to a toaster, it is not smarter. History of Computer  2700 BC: Abacus, first „computer‟  1927: Differential analysis / analogue computing device (used to count votes)  1942: Cannon trajectories such as „Enigma‟ o Made use of vacuum tubes that were used to create a gate, or a circuit o Hundreds of gates were tied together to create a single computer, such as ENIAC and Colossus. o Programmed by bootstrapping the computer. Much faster than humans, and always correct. o First computer bug – actual bugs that had to be caught by-hand to prevent destruction of vacuum tubes.  1947: Silicone sink that does the same thing that vacuum tubes did, and were designed to be airborne radars o Transistors were more powerful and did not have so much heat, size, and weight o Eventually replaced tubes in everything from radios to x-ray machines, and ushered in the electronic age o Allowed the building of modern digital devices like IBM 360  1960: Computers become great as tabular machines at collating and storing data. o Access was very limited, with main availability in large businesses and universities. o Input was still laborious, requiring punch cards and batch jobs.  1965: Moore‟s Law “The processing power of computer will double every two years” o This has held true to today since 1965  1975: Microchip is created, and is used to create the first home computers. This also leads to: o Creation of Microsoft (1975) o Creation of Apple II (1977) o Creation of IBM PC (1981)  1980~ (in order) o Introduction of CRT Monitors, which allowed direct input via typing o Introduction of personal computers, with software for home, business, and game o Creation of sound cards o Creation of video cards o Creation of laptops o Computers become ubiquitous and are found everywhere o Advanced Research Projects Agency (ARPA) creates Arpanet in case of nuclear war o Creation of internet (The backbone of long-distance communication) o Creation of the World Wide Web (A subset on top of the internet that allows HTML) How a computer understands and ‘sees the world’  A computer is merely aware of a single factor: low voltage (off) and high voltage (on)  We represent these two state as zero (0) and one (1)  Machine Language: Set of instruction that the CPU can access directly o Binary: A base 2 numerical system that only makes use of 0 and 1 o Computers only understand „on‟ and „off‟, and therefore binary is the most suitable numerical system o Remember: 128, 64, 32, 16, 8, 4, 2, 1, and think of binary as symbols instead of numbers o Break numbers: Breaking binary into units:  BIT = 1 binary  Byte: 8 BITs (~1 alphabetical character)  Kilobyte: 1,000 BITs (~ 1/3 of a page)  Megabyte: 1,000,000 BITs (~1/2 of an average book)  Gigabyte: 1,000,000,000 BITs (~500 books)  Terabyte: 1,000,000,000,000 BITs (
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