Jan 10, Hardware and Software

Jan 10, Hardware and Software - Hardware and Software...

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Unformatted text preview: Hardware and Software 23/01/2008 14:10:00 Computers Computers are automatic, electronic machines that o Accept data and instructions from a user (INPUT) o Store the data and instructions (STORAGE) o Manipulate the data according to the instructions (PROCESSING) o Store and/or output the results to the user (OUTPUT) A computer system is composed of hardware and software Hardware components are the physical, tangible pieces that we can see and touch Software Program o A sequence of instructions to accomplish a result o A computer processes information under the direction of a program Data o Information to be processed by a program Example o Data : for each employee, the employee number, hours worked and hourly pay rate o Program : instructions on how to process the data to produces pay cheques, payroll register, etc. Hardware Digital Computers o The computers that we use are digital, not analogue computers o Analogue technology The signal directly analogous to the information it represents The signal is continuous and in direct proportion to the source of the information In a thermometer, mercury rises in direct proportion to the temperature In an amplifier or telephone, the electronic voltage signal varies in direct proportion ot the frequency and amplitude of the sound waves it represents o Digital technology The signal is discrete The information is broken down into pieces, and each is represented separately Analogue information is measured many times per second (the sampling rate) and each measurement is represented as a number How music is stored on a compact disc the disc stores numbers representing specific voltage levels sampled at specific voltage levels sampled at specific times Can be used to digitize sound, video, graphics, etc. o Out computers work with digital technology, hence the term digital computers Storage of Programs and Data o Sampling is only one way to digitize information o Since our computers work ONLY with numbers, everything (not just analogue information such as sound and video) must be converted to numbers Text (letters and special characters) gets converted to numbers (A = 65), using a standard coding convention call ASCII Graphics (images), gets broken down into pieces (pixels) and each colour gets a number Binary Numbers o But how do we store numbers in a computer?...
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Jan 10, Hardware and Software - Hardware and Software...

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