How Do Computers Work? A Gentle Introduction for Kids

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How Do Computers Work? A Gentle Introduction Poly Pride

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*How Do Computers Work? Part III Dr. A. Sanchez*Hardware and SoftwareHardware the physical, tangible parts of a computer keyboard, monitor, disks, wires, chips, etc. Software programs and data a program is a series of instructions A computer requires both hardware and software Each is essentially useless without the other

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*How Do Computers Work? Part III Dr. A. Sanchez*CPU and Main MemoryCentral Processing UnitChip that executes program commands Intel Pentium 4 Sun ultraSPARC IIIPrimary storage area for programs and data that are in active use Synonymous with RAM

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*How Do Computers Work? Part III Dr. A. Sanchez*Secondary Memory DevicesInformation is moved between main memory and secondary memory as neededCentral Processing UnitSecondary memory devices provide long-term storageHard disks Floppy disks ZIP disks Writable CDs Writable DVDs Tapes

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*How Do Computers Work? Part III Dr. A. Sanchez*Input / Output DevicesCentral Processing UnitI/O devices facilitate user interactionMonitor screen Keyboard Mouse Joystick Bar code scanner Touch screen

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*How Do Computers Work? Part III Dr. A. Sanchez*Software CategoriesOperating System controls all machine activities provides the user interface to the computer manages resources such as the CPU and memory Windows XP, Unix, Linux, Mac OS Application program generic term for any other kind of software word processors, missile control systems, games Most operating systems and application programs have a graphical user interface (GUI)

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*How Do Computers Work? Part III Dr. A. Sanchez*Analog vs. DigitalThere are two basic ways to store and manage data: Analog continuous, in direct proportion to the data represented music on a record album - a needle rides on ridges in the grooves that are directly proportional to the voltages sent to the speaker

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*How Do Computers Work? Part III Dr. A. Sanchez*Analog vs. DigitalDigital the information is broken down into pieces, and each piece is represented separately music on a compact disc - the disc stores numbers representing specific voltage levels sampled at specific times

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*How Do Computers Work? Part III Dr. A. Sanchez*Digital InformationComputers store all information digitally: numbers text graphics and images video audio program instructions In some way, all information is digitized - broken down into pieces and represented as numbers

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*How Do Computers Work? Part III Dr. A. Sanchez*Representing Text DigitallyFor example, every character is stored as a number, including spaces, digits, and punctuation Corresponding upper and lower case letters are separate charactersH i , H e a t h e r .

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*How Do Computers Work? Part III Dr. A. Sanchez*Binary NumbersOnce information is digitized, it is represented and stored in memory using the binary number system A single binary digit (0 or 1) is called a bit Devices that store and move information are cheaper and more reliable if they have to represent only two states

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*How Do Computers Work? Part III Dr. A. Sanchez*Binary NumbersA single bit can represent two possible states, like a light bulb that is either on (1) or off (0) Combinations of bits are used to store values

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*How Do Computers Work? Part III Dr. A. Sanchez*Bit CombinationsEach additional bit doubles the number of possible combinations

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*How Do Computers Work? Part III Dr. A. Sanchez*Bit CombinationsEach combination can represent a particular item There are 2N combinations of N bits Therefore, N bits are needed to represent 2N unique items21 = 2 items22 = 4 items23 = 8 items24 = 16 items25 = 32 items

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*How Do Computers Work? Part III Dr. A. Sanchez*Bit CombinationsSuppose we have three bits … see how different numbers are represented with them101522 = 401++=5111722 = 421 = 21++=7

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*How Do Computers Work? Part III Dr. A. Sanchez*Bit CombinationsSince you were very small, people have told you that you can count up to 10 with your two hands, right? Well … you can do better than this … With one hand you can count up to 31 … With two hands you can count up to 1023 … How

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*How Do Computers Work? Part III Dr. A. Sanchez*Bit Combinations

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*How Do Computers Work? Part III Dr. A. Sanchez*Bit CombinationsWhat number is this??NOT Showing SHOWING!1

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*How Do Computers Work? Part III Dr. A. Sanchez*Bit CombinationsWhat number is this??NOT Showing SHOWING!2NOT Showing

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*How Do Computers Work? Part III Dr. A. Sanchez*A Computer SpecificationConsider the following specification for a personal computer: 2.8 GHz Pentium 4 Processor 512 MB RAM 80 GB Hard Disk 48x CD-RW / DVD-ROM Combo Drive 17” Video Display with 1280 x 1024 resolution 56 Kb/s Modem What does it all mean?

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*How Do Computers Work? Part III Dr. A. Sanchez*MemoryRemember this?

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*How Do Computers Work? Part III Dr. A. Sanchez*Storing Information9278 9279 9280 9281 9282 9283 9284 9285 928610011010

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*How Do Computers Work? Part III Dr. A. Sanchez*Storage CapacityEvery memory device has a storage capacity, indicating the number of bytes it can hold Capacities are expressed in various units:KB 210 = 1024MB 220 (over 1 million)GB 230 (over 1 billion)TB 240 (over 1 trillion)Unit Symbol Number of Byteskilobyte megabyte gigabyte terabyte

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*How Do Computers Work? Part III Dr. A. Sanchez*MemoryMain memory is volatile - stored information is lost if the electric power is removed Secondary memory devices are nonvolatile Main memory and disks are direct access devices - information can be reached directly The terms direct access and random access often are used interchangeablyMeaningPronunciation

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*How Do Computers Work? Part III Dr. A. Sanchez*MemoryA magnetic tape is a sequential access device since its data is arranged in a linear order - you must get by the intervening data in order to access other information

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*How Do Computers Work? Part III Dr. A. Sanchez*RAM vs. ROMRAM - Random Access Memory (direct access) ROM - Read-Only Memory The terms RAM and main memory are basically interchangeable ROM could be a set of memory chips, or a separate device, such as a CD ROM

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Last Updated: 8th March 2018

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