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Electrical Engineering and Computer Science
EECS 1520
Hernan Humana

Computer Science Computing System: dynamic entity used to solve problems and interact with its environment. Computer hardware: collection of physical elements that make up the machine. Computer software: collection of programs that provide instructions Layers of a Computing System: Information->Hardware->Programming->Operating systems- >Applications->Communications. Information: How we represent information on a computer using binary digits.(Ch2,3) Hardware: Physical hardware of a computer system that keeps the flow of electricity (4,5) Programming: Uses software instructions used to complete computations. (6-9) Operating System: Manages computers resources (10,11) Applications: Help take advantage of the computer’s abilities in other areas. (12-14) Communications: Use technology to communicate through computers (15, 16) Abstraction: Mental model that removes complex details. File: a name collection of related data made from 0 and 1. File System: operating systems logical views of files it manages Directory: A named group of files (folder) Text-file: a file where the bytes of data are organized as characters from Unicode Binary: a file that contains data in specific format, requiring interpretation File-Type: Indicated the file type Atomic Operations: delete, open, close, rename, copy Processing Data: read, write, remove and add data Sequential Access: information is processed in order Direct Access: Files are accessed in a logical order File Protection: primary importance to keep our files safe. Determines who uses the files Directory Tree: file systems are organized into a hierarchy Root Directory: where the file system starts Path: location of files in a file system though a series of directory Absolute Path: begins at the root directory Relative Path: begins at the current or working directory Working Directory: the subdirectory in which you are working. LEFT The leftmost characters from the specified text IF If the test is true, it returns true_val, otherwise it returns the false_val ISBLANK Returns true if the specified value refers to an empty cell A1…B9 Range of cells Sum Sum or specified of set values Count Count the # of cells Max Largest value from the specified set SIN The sine of specified angle PI Value of pi STDEV Standard deviation from the specified sample values TODAY Todays date Managing Information: Information system: software that helps us organize and analyze data Spreadsheet: A software application that allows the user to organize/analyze data using a grid of cells Cell: Referred to by column and row. It can numerical data or string (text). Range: A1..B9, two dots between two cells. CH 3: Data And Computers Analog and Digital Information:  Real world is infinite and continuous  Data on computers are finite  Need to obtain a finite approximate of the world, sufficient for our computational needs and 5 senses.  Analog data: info represented in a continuous form  Digital data: info represented in a discrete form; sound of record vs disk.  Information is digitized by breaking into numbered pieces  Binary (0 or 1) Binary Representation  2 bits produce 2^n different bit pattern  actual number of bits is influences by other factors Representing Text  English: 26 letters  Determine the minimum number of bits needed and pair them off. ADCII  Each character is coded as 8 bits, (0-7)  2^7 (128 codes)  95 graphical (visible), 33 control (invisible) Unicode Character Set:  16-bit standard (2^16) Text compression:  Substitute a frequency used word with a single character. Ex: as(^), and(+), that($)  Problems: character can’t be apart of the text. Word variations not handled. Run Length Encoding  Replace long series of repeated characters with a count of repetition. Ex: AAAAAAAA = A7 Huffman Encoding  Generalization of Morse code  Dots and dashes is based on distribution of letters  Distribution in a given message the algorithm.  Encoding: build frequency table of letter usage in message, build the code, encode the message  Decoding: Huffman code has the prefix property( no code is the front part of another code) Audio Information:  Physical of sound  Carried by an electronic wave  Electronic wave is an analog (continuous functions)  Audio formats: mp3( MPEG Audio layer 3, uses lossy( math models of human sychoacoushes to discard info the human ear can’t hear) and lossless(bit stream compressed by a form of Huffman encoding) compression, wav, aiff Images and Graphics  Raster: image divided into rows and columns  Pixel: each rectangle hold picture info  Compression takes up a lot of space  Vector graphics math equations to represent shapes  Good for line art/cartoons Representing Real Numbers:  Fractions  Base: b any integer is greater than 1. Representing Video  A stream of images at 24-30 frames/second  Temporal compression: key frame + series of delta frames that record only changes from key frame  Spatial compression: removes redundant info within a frame (jpeg like compression on each frame) Birth of The Computer:  Konrad Zuse - Designed the ‘Z’ series of automatic general purpose computing machine - -Electro-mechanical devices - -Binary - Z 3 was programmed using punched 35mm film.  Alan M. Turing - Led the WWII research group that broke the code for the Enigma Machine (fooled Germans about invasion) - Proposed a simple abstract universal machine model for defining computability: The ‘ Turning Machine’ - Devised the ‘turning hypothesis for Al.  IBM Harvard Mark 1 -The IBM automatic Sequence controlled calculator was installed at Harvard U. -5ft. 5 tons, 750000 parts, 72 accumulators, 60 sets of rotary switches  Mauchly & Eckert - headed the ENIAC team (Electronic Numerical Integrator And Computer) :general purpose computer. - Commissioned by the Army for computing ballistic firing tables - Decimal internal coding - Manual programming of boards, switches and functional table.  Jon Von Neumann - Prepares a draft for an automatic programmable device called EDVAC (stored program) - Designed the Institute for Advances Studies machine, which became operational in 1951. - -Binary, fetch decode execute. History:  Great Britain had a ‘stongehenge’, which seemed to be an early form of the calendar.  The ‘abacus’ 1600B.C. used to record numeric values  1700 Blaise Pascal built a gear driven machine, which performed whole number addition and subtraction.  1700 Gottfried Vilhelm von Leibniz built a mechanical machine to do addition subtraction multiplication and division (not reliable)  1800 Joseph Jacquard designed a weaving cloth machine, which used cards with holes. ‘The punched card’  1900 Charles Babbage designed analytical engine. Too complex but his image is incorporated into many modern computers. (Memory, input of both # and steps)  Ada Augusta is credited as the first programmer  Willaim Burrough made and sold an adding machine  Dr. Herman Hollerith developed a electro mechanical tabulator which read info from punched cards.  1936 Alan Turning invented an abstract math model called turning machine.  Jon Von Neumann made a machine called EDVAC which was completed in 1950.  1951 first commercial computer First Generation: 1951-1959  Commercial computers were built using vacuum tubes to store information  The vacuum tubes generated lots of heat and not reliable  Memory device: magnetic drum  Peripheral device
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