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Computer Computers are only tools,  designed by people,  programmed by people, and  used by people Computers exist to benefit and assist people, not

Jan 13, 2016

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  • ComputerComputers are only tools,designed by people,programmed by people, andused by people

    Computers exist to benefit and assist people, not to replace them

    Computers are depending upon people

  • The von Neumann MachineDr. John von Neumann, American mathematician, presented the stored program concept (in 1945)both data and instructions are stored in a single read-write memorythe read-write memory are addressed by location, without regard to the type of dataexecution occurs in sequence fashions (unless explicitly modified) from one instruction to the next

  • The System UnitWhat is the system unit? p. 180 Fig. 4-1Case that contains electronic components of the computer used to process dataSometimes called the chassis

  • The System UnitWhat are common components inside the system unit?p. 181 Fig. 4-2MemoryAdapter cardsSound cardModem cardVideo cardNetwork cardPortsDrive baysPower supplyProcessor

  • The System UnitWhat is the motherboard?Main circuit board in system unitContains adapter cards, processor chips, and memory chipsAlso called system board

  • The Components of a computer

  • ProcessorWhat is the central processing unit (CPU)?Arithmetic Logic Unit (ALU)Input DevicesStorage DevicesOutput DevicesInterprets and carries out basic instructions that operate a computerMemoryDataInformationControl UnitControl unit directs and coordinates operations in computerArithmetic logic unit (ALU) performs arithmetic, comparison, and logical operationsAlso called the processor

  • CPU (Central Processing Unit)The most complex computers component

    The brain and the heart of the computer

    Determines whether a computer is fast or slow in relation to other computers

  • CPU (Central Processing Unit)Controls the overall operation and performs arithmetic and logic functions of the computer

    Consists of 3 important partsArithmetic and logic unit (ALU)Control unitRegisters

  • ALU (Arithmetic and Logic Unit)The functional unit of a computer hardware system that carries out all of the arithmetic operationsaddsubtractmultiplydivideand all logical operations:ANDORNOT

  • Control UnitActs like a traffic cop who directs the flow of data throughout the system

    It is the functional unit thatstarts execution of the programcontrols sequence of executioncontrols read/write on main memorycontrols operations of ALUinitiates and controls input/output (I/O) operations on various I/O devices

  • ProcessorWhat is a machine cycle?Step 1. Fetch Obtain program instruction or data item from memoryStep 2. Decode Translate instruction into commandsStep 4. Store Write result to memoryStep 3. Execute Carry out commandFour operations of the CPU comprise a machine cycle

  • ProcessorWhat is a register?Stores location from where instruction was fetchedStores instruction while it is being decodedp. 185Stores data while ALU computes itStores results of calculationTemporary high-speed storage area that holds data and instructions

  • ProcessorWhat is the system clock?Each tick is a clock cyclePace of system clock is clock speedMost clock speeds are in the gigahertz (GHz) range (1 GHz = one billion ticks of system clock per second)Processor speed can also be measured in millions of instructions per second (MIPS)Controls timing of all computer operationsGenerates regular electronic pulses, or ticks, that set operating pace of components of system unit

  • ProcessorHow do personal computer processors compare?

  • ProcessorWhich processor should you select?The faster the processor, the more expensive the computer

  • ProcessorWhat is parallel processing?p. 190 Fig. 4-12Control ProcessorResults combinedUsing multiple processors simultaneously to execute a program fasterRequires special software to divide problem and bring results together

  • Data RepresentationHow do computers represent data?p. 191 Fig. 4-13Recognize only two discrete states: on or offUse a binary system to recognize two statesUse Number system with two unique digits: 0 and 1, called bits (short for binary digits)Most computers are digital

  • Data RepresentationWhat is a byte?p. 191 Fig. 4-14Eight bits grouped together as a unitProvides enough different combinations of 0s and 1s to represent 256 individual charactersNumbersUppercase and lowercase lettersPunctuation marks

  • Data RepresentationWhat are three popular coding systems to represent data?p. 192 Fig. 4-15ASCIIAmerican Standard Code for Information InterchangeEBCDICExtended Binary Coded Decimal Interchange CodeUnicodecoding scheme capable of representing all worlds languages

  • Data RepresentationHow is a letter converted to binary form and back?p. 193 Fig. 4-16Step 2. An electronic signal for the capital letter D is sent to the system unit.Step 3. The signal for the capital letter D is converted to its ASCII binary code (01000100) and is stored in memory for processing.

  • MemoryWhat is memory?p. 193 Fig. 4-17Electronic components that store instructions, data, and resultsConsists of one or more chips on motherboard or other circuit boardEach byte stored in unique location called an address, similar to seats on a passenger trainSeat #2B4Seat #2B3

  • Main MemoryTemporarily holds data and instructions needed by the CPU

    Called primary memory (storage), internal memory or random access memory (RAM)

    Random Access Memory data can be stored and retrieved at random in approximately equal amounts of time, no matter what the specific data locations are

  • MemoryHow is memory measured?p. 194 Fig. 4-18By number of bytes available for storage

  • MemoryWhat is random access memory (RAM)?p. 195The more RAM a computer has, the faster it respondsAlso called main memory or primary storageMost RAM is volatile, it is lost when computers power is turned offMemory chips that can be read from and written to by processor

  • MemoryHow do program instructions transfer in and out of RAM?Step 1. When you start the computer, certain operating system files are loaded into RAM from the hard disk. The operating system displays the user interface on the screen.Operating system instructionsWeb browser instructionsWord processing program instructionsOperating system interfaceWeb browser windowWord processing program windowWeb browser program instructions are removed from RAMWeb browser window no longer is displayed on desktopStep 2. When you start a Web browser, the programs instructions are loaded into RAM from the hard disk. The Web browser window is displayed on the screen.Step 3. When you start a word processing program, the programs instructions are loaded into RAM from the hard disk. The word processing program, along with the Web Browser and certain operating system instructions are in RAM. The word processing program window is displayed on the screen.Step 4. When you quit a program, such as the Web browser, its program instructions are removed from RAM. The Web browser no longer is displayed on the screen.

  • MemoryWhat are two basic types of RAM chips?p. 196Static RAM (SRAM)Dynamic RAM (DRAM)Future: Magnetoresistive RAM (MRAM)

  • MemoryWhere does memory reside?p. 196 Fig. 4-20Resides on small circuit board called memory moduleMemory slots on motherboard hold memory modulesmemory chipmemory slotdual inline memory module

  • MemoryHow much RAM does an application require?p. 197 Fig. 4-21Software package typically indicates RAM requirementsFor optimal performance, you need more than minimum specifications

  • MemoryHow much RAM do you need?p. 197 Fig. 4-22Depends on type of applications you intend to run on your computer

  • MemoryWhat is cache?L1 cache built into processorL2 cache slower but has larger capacityL2 advanced transfer cache is faster, built directly on processor chipL3 cache is separate from processor chip on motherboard (L3 is only on computers that use L2 advanced transfer cache)Helps speed computer processes by storing frequently used instructions and dataAlso called memory cache

  • MemoryWhat is read-only memory (ROM)?p. 198Memory chips that store permanent data and instructionsNonvolatile memory, it is not lost when computers power is turned offThree types:Firmware Manufactured with permanently written data, instructions, or information

    EEPROM (electrically erasable programmable read-only memory) Type of PROM containing microcode programmer can erase

    PROM (programmable read-only memory) Blank ROM chip onto which a programmer can write permanently

  • MemoryWhat is access time?p. 200 Figs. 4-25-4-26Amount of time it takes processor to read data from memoryMeasured in nanoseconds (ns), one billionth of a secondIt takes 1/10 of a second to blink your eye; a computer can perform up to 10 million operations in same amount of time

  • Expansion Slots and Adapter CardsWhat is an adapter card?Enhances system unit or provides connections to external devices called peripheralsAlso called an expansion card

  • Expansion Slots and Adapter CardsWhat is an expansion slot?p. 201 Fig. 4-28An opening, or socket, on the motherboard that can hold an adapter cardWith Plug and Play, the computer automatically configures cards and other devices as you install them

  • Expansion Slots and Adapter CardsWhat are PC cards and flash memory cards?A PC card adds memory, storage, sound, fax/modem, communications, and other capabilities to notebook computersA flash memory card allows users to transfer data from mobile devices to desktop computersHot plugging allows you to insert and remove cards while computer is running