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In this chapter, learn about the four basic types of system units, how computers use binary codes, the major components of a system unit, and the function of system clocks, expansion slots, and bus lines. Discover the different types of memory, the role of microprocessors, and the importance of ports, cables, and power supply.
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6 CHAPTER THE SYSTEM UNIT
Competencies • Describe the four basic types of system units • Discuss how a computer uses binary codes • Describe the major system unit components • Describe system boards, microprocessors, and memory • Describe the function of the system clock, expansion slots, boards, and bus lines • Discuss ports, cables, and power supply
System UnitsMicrocomputers • Desktop • Notebook • Tablet PC • Handheld
Electronic Data and Instructions • Data and instructions are represented electronically • Computers recognize digital signals • Binary system • Bit • Byte
Binary Coding Scheme • Two state system • Off/on electrical states • Characters represented by 0s and 1s • Three types of schemes • ASCII - American Standard Code for Information Exchange • EBCDIC - Extended Binary Coded Decimal Interchange Code • Unicode
System Board • Connects all components • Allows communication between devices • Main board or motherboard • Circuit board electronic components • Sockets • Slots • Bus lines
Microprocessor • Central Processing Unit (CPU ) • Two basic components • Control unit • Arithmetic and logic unit
Microprocessor Chips • Chip capacities are expressed in word sizes • Types of microprocessor chips • CISC chips: Complex instruction chips • Most widely used design • Used by Intel • RISC chips: Reduced instruction set computer chips • Uses fewer instructions • Design is simpler and less costly • Used by the PowerPC
Specialty Processors • Graphics coprocessors • Parallel processors • Smart cards
Memory • Holding area for data, instructions, and information • Types of memory chips • RAM – holds programs and data • ROM – fixed start-up instructions • CMOS – flexible start-up instructions
System Clock • Important measurement indicating speed • Located on a small chip • Produces electrical beats • Synchronizes operations • Expressed in gigahertz • Faster clock speed, faster computer What is a gigahertz?
Expansion Slots and Cards • Allow for new devices to be added • Open architecture • Slots provide for expansion • Expansion cards are also called … • Plug-in boards • Controller cards • Adapter cards • Interface cards
Commonly Used Expansion Cards • Video cards • Modem cards • Network interface cards (NIC) • TV tuner cards • PC cards
Bus Lines • Connect parts of the CPU to each other • Data roadway for traveling bits • Measured as bus width • More lanes, faster traffic • Two basic categories • System buses • Expansion buses
Types of Expansion Buses • Industry Standard Architecture (ISA) • Peripheral Component Interconnect (PCI) • Advanced Graphic Port (AGP) • Universal serial bus (USB) • FireWire buses • HPSB – high performance serial bus • Used with digital camcorders & video editing software
Ports • Socket for connecting external devices • Four common ports • Serial • Parallel • USB • FireWire
Power Supply Unit AC adapter Power Supply • Computers require direct current (DC) • DC power provided by converting alternating current (AC) from wall outlets or batteries • Desktop computers use power supply units • Notebooks and handhelds use AC adapters
A Look to the FutureXybernaut Corporation • Wearable computers • Called POMA • Includes… • Windows CE • Wireless pointing device • Head-mounted display • MP3 player • Abridged Windows Office programs
AC adapter (164) accelerated graphics port (AGP) (163) adapter card (159) alternating current (AC) (164) analog (151) arithmetic operation (155) Arithmetic logic unit (AL ASII (152) binary coding scheme (152) binary system (151) bit (151) bus (162) bus line (154) bus width (162) byte (151) Key Terms
video card (159) video capture card (159) video recorder card (159) volatile storage (157) virtual memory (157) word (155) workstation (155) Key Terms
FAQs • What are the four basic types of system units? • What is analog? What is digital? • What is a microprocessor and what does it do? • What is RAM? What is ROM? • I hear a lot about flash memory. What is it? • I need a USB port to install a wireless mouse. What are ports? • What is a network card?
Discussion Questions • Explain how a computer understands instructions. • Define memory and describe three types of memory chips. • Explain the purpose of expansion cards and slots. Give examples of some commonly used expansion cards. • Describe how bus lines work.