66 CHAPTER THE SYSTEM UNIT

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. What is System Unit? Box-like case that contains computer’s electronic components. Sometimes called the chassis 6-2

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 6-3 Competencies Four basic types of system units Major system unit components Describe system boards, microprocessors, and memory Binary codes Expansion slots, boards, and bus lines Ports, cables, and power supply

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 6-4 System Units Microcomputers Desktop Notebook Tablet PC Handheld

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. INSERT VIEW OF SYSTEM UNIT 6-5

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. INPUT/OUTPUT PORT (I/O PORT) Figure 4 Back View of a System Unit 6-6

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 6-7

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. FUNCTIONS OF THE MAIN COMPONENTS OF A SYSTEM UNIT NONO COMPONENTSFUNCTIONS 1Input/output port (I/O port) A port is the point at which a peripherals attaches to a system unit so that the peripherals can send data to receive information from the computer. An external device, such as keyboard, monitor, printer, mouse and microphone is often attached by cable to a port on the system unit. The back of the system unit contains so many ports. Some newer personal computers also have ports on the front of the system unit. Ports have different types of connector. A connector joins a cable to a peripheral. One end of a cable attaches to the connector on the system unit and the other end of the cable attaches to a connector on the peripherals. 6-8

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. NONO COMPONENTSFUNCTIONS 2Power ButtonTo start on computer 3Reset ButtonKick of soft boot, instructing the computer to go through the process of shutting down, which would clear memory and reset devices to the initialized state. It simply removes power immediately 4MotherboardMain circuit board of the system unit, which has some electronic components attached to it and others built into it. 5Power SupplyConvert standard electrical power into the form that computer can use. If power supply is not providing the necessary power, the computer will not function properly. 6DVD-ROM driveA device that reads audio CD’s, CD-ROMSs, CD-Rs and D- RWs. 7CD-ROM drive.A devise that reads audio CDs, CD-ROMSs, CD-Rs and CD- REWs. 8DVD/CD-RW driveIt is a combination drive that reads DVD and CD media, it also writes to CD-RW media. This drove also allows watching a DVD or burn a CD. 6-9

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. NONO COMPONENTSFUNCTIONS 9Zip driveA high-capacity disk drive that reads from a writes on a ZIP disk 10Floppy driveA device that reads from and writes on a Zip disk 11Hard disk driveType of storage device that contains one or more inflexible, circular platters that store data, instructions and information. Also called a hard disk. 6-10

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. THE COMPONENTS OF A MOTHERBOARD 6-11

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 6-12

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 6-13

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. NONO COMPONENTSFUNCTIONS 1Central Processing Unit (CPU) A Central Processing Unit CPU is a microprocessor (or processor for short). It is an integrates circuit chip that is capable or processing electronic signals. The CPU is the most important element in a computer system. A CPU interprets instructions given by the software and carries out those instructions by processing data and controlling the rest of the computer’s components. 2Random Access Memory (RAM)  RAM is installed inside computers. RAM is also known as a working memory.  The data in RAM can be read (retrieved) or written (stored).  RAM is volatile which means the programs and data in RAM are lost when the computer is power off.  A computer used RAM to hold temporary instructions and data needed to complete tasks. This enables the computer’s CPU to access instructions and data stored in the memory very quickly.  RAM stores data during and after processing. FUNCTIONS OF THE COMPONENTS OF THE MOTHERBOARD 6-14

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. NONO COMPONENTSFUNCTIONS 3Read Only Memory (ROM) ROM is another type of memory permanently stored inside the computer. ROM is non-volatile. It holds the programs and data when computer power ff. Programs in ROM have been [re-recorded. It can only be stored by manufactures, once it is done, it cannot be changed. Many complex functions, such as start up operating instructions, translators for high-level languages and operating systems are placed in ROM memory. All the contents in ROM can be accessed and read but cannot be changed. 4Expansion SlotsExpansion slots are the sockets where the circuit boards or the adapter cards can be inserted into motherboard. It is a place to fit an expansion card containing the circuitry that provides some specialized capability, such as video acceleration, sound or disk drive control. 6-15

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 6-16

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved System Board Main board or motherboard Connects all components Allows communication between devices Circuit board electronic components Sockets Slots Bus lines

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Microprocessor Central Processing Unit (CPU ) - Two basic components Control unit  Tell the rest of the computer how to carry out a program’s instructions  It directs the movement of electronic signals between memory, instructions and arithmetic logic unit.  Direct control signals between the CPU and I/O devices. Arithmetic and logic unit (ALU) Perform two types of operations Arithmetic and logic

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 6-19

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Specialty Processors Coprocessors Designed to improve specific computing operations Graphics Card, Sound Cards Smart cards Credit card sized with an embedded chip Used by many universities, Bank Specialty processors Car, A/C, Mobile

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Memory Holding area for data, instructions, and information Types of memory chips RAM – holds programs and data ROM – fixed start-up instructions Cache Memory –Used to speed up processing Registers- High Speed memory

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Cache Memory and Register 6-22 Processor Cache Memory RAM Registers

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Electronic Data and Instructions Data and instructions are represented electronically Computers recognize digital signals Binary system Bit Byte What is the difference between digital and analog

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved 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( used for large computers) Unicode ( for international languages like Chinese and Japanese.

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Memory Capacity No of BitsSize 1024 Bytes1 KB 1024 KB1 MB 1024 MB1 GB 1024 GB1 TB 1024 TB1 PB PB1 ZB 4 bits= I nibble 8 bits= 1 Byte

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Binary Code CodeUses ASCII American Standard Code for Information Interchange Microcomputers EBCDIC Extended Binary Coded Decimal Interchange Code Large Computers UnicodeInternational Languages

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Expansion Slots and Cards Expansion cards are also called Plug-in boards Controller cards Adapter cards Interface cards 6-27

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Commonly Used Expansion Cards Graphics cards Sound cards Network interface cards (NIC) Wireless network cards Modem Cards TV tuner cards 6-28

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. TV Tuner Cards And Video Clips Allows you to view your favorite TV shows while running other applications such as Excel Video can be captured to a file, added to a Web page, attached to an , or added to a class presentation Inexpensive and easy to install 6-29

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Plug and Play Set of specific hardware and software standards developed by Intel, Microsoft, and others Creating devices that are able to configure themselves when installed 6-30

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 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 6-31

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Ports Socket for connecting external devices Ports can connect directly to the system board or they can connect to cards that are inserted into slots on the system board Three Types Standard Ports Legacy Ports Specialized Ports 6-32

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Standard Ports Four common ports VGA USB ports FireWire ports Ethernet ports Return 6-33

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Legacy Ports Serial ports Parallel ports Keyboard and mouse ports Game ports Return 6-34

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. Specialized Ports Three specialized ports Musical Instrument digital interface (MIDI) High Definition Multimedia Interface (HDMI) Return 6-35