© 2008 Prentice-Hall, Inc. 1 Technology in Action

© 2008 Prentice-Hall, Inc. 2 Technology in Action Chapter 9 Behind the Scenes: A Closer Look at System Hardware

© 2008 Prentice-Hall, Inc. 3 Chapter Topics Computer switchesComputer switches Binary number systemBinary number system Inside the CPUInside the CPU Cache memoryCache memory Types of RAMTypes of RAM Computer busesComputer buses Creating faster CPUsCreating faster CPUs

© 2008 Prentice-Hall, Inc. 4 Binary Language Computers work in binary languageComputers work in binary language Consists of two numbers: 0 and 1Consists of two numbers: 0 and 1 Everything a computer does is broken down into a series of 0s and 1sEverything a computer does is broken down into a series of 0s and 1s Switches: Devices inside the computer that can be flipped between these two states: 1 or 0, on or offSwitches: Devices inside the computer that can be flipped between these two states: 1 or 0, on or off

© 2008 Prentice-Hall, Inc. 5 Switches Nonmechanical devices in computers that open and close circuitsNonmechanical devices in computers that open and close circuits Types of electrical switches:Types of electrical switches: –Vacuum tubes –Transistors: SemiconductorsSemiconductors –Integrated circuits Vacuum Tube Transistors Integrated Circuits

© 2008 Prentice-Hall, Inc. 6 The on/off state of a switch represents one bit of dataThe on/off state of a switch represents one bit of data Bit (binary digit)Bit (binary digit) –On = 1 –Off = 0 OFF 0 Switches Representing Data ON 1 01 OR = 1 bit

© 2008 Prentice-Hall, Inc. 7 The Binary Number System Describes a number as powers of 2Describes a number as powers of 2 Also referred to as base 2 numbering systemAlso referred to as base 2 numbering system Used to represent every piece of data stored in a computer: all of the numbers, letters, and instructionsUsed to represent every piece of data stored in a computer: all of the numbers, letters, and instructions

© 2008 Prentice-Hall, Inc. 8 The Binary Number System Number systems are organized ways to represent numbersNumber systems are organized ways to represent numbers Each number in one system has a corresponding number in another.Each number in one system has a corresponding number in another = 89 Binary Base x x x x8 8 2x4 4 2x2 2 2x1 1 Binary Base = 89

© 2008 Prentice-Hall, Inc. 9 Representing Letters and Symbols American Standard Code for Information Interchange (ASCII) –8 bits = 1 byte = alphanumeric character or symbol –256 different combinations UnicodeUnicode –16 bits equal 1 byte –65,000 different combinations, used for all languages = a = A = # = m ASCII

© 2008 Prentice-Hall, Inc. 10 ASCII Chart

© 2008 Prentice-Hall, Inc. 11 The CPU: Processing Digital Information The CPU is the brains of the computerThe CPU is the brains of the computer Different types of CPUsDifferent types of CPUs –Intel and AMD chips: Used in most Windows-based PCs –Apple systems use different CPU design Differentiating CPUsDifferentiating CPUs –Processing power –Clock speed and cache

© 2008 Prentice-Hall, Inc. 12 Processors on the Market Today ProcessorManufacturerNumber of Transistors Typical Clock Speed Levels of Cache Storage Description Athlon 64 FX – 60 AMD233 million2.6 GHz264-bit processor for heavy computation and demanding video gaming needs. Core Duo Intel151.6 million GHz2Designed specifically for mobile computers; transfers power only to those areas of the processor that need it, improving battery life. Itanium 2 Intel410 million1.3 – 1.66 GHz3Seen in high-end server computers. Pentium 4 Extreme Edition 955 Intel225 million3.46 GHzEach processor core has its own 2 MB L2Cache This processor uses a dual–core design and hyperthreading to Process four tasks at once. Pentium D Dual Core Intel230 million GHz2New dual-core processor for more efficient multitasking. No hyperthreading capabilities. PowerPC G4 Freescale Semiconductor (once part of Motorola) 57 million1.5 – 1.67 GHz3Until 2006, powered the Apple line of computers. Dual Core PowerPC G5 IBM58 million GHz2Powerful 64-bit processor for heavy computational needs. Sempron AMD68.5 million2.0 GHz2Affordable performance for today’s value-conscious buyers of desktop PCs. Turion AMD114 million1.6 – 2.4 GHz2Optimized for better performance in thinner and lighter laptops for longer battery life and compatible with wireless technologies.

© 2008 Prentice-Hall, Inc. 13 The CPU Machine Cycle FetchFetch –The program’s binary code is “fetched” from its temporary location in RAM and moved to the CPU DecodeDecode –The program’s binary code is decoded into commands that the CPU understands. ExecuteExecute –The ALU performs the calculations. StoreStore –The results are stored in the registers “Inside the Chip” by Intel Video Clip

© 2008 Prentice-Hall, Inc. 14 The System Clock Located on the motherboardLocated on the motherboard Controls the CPU’s processing cyclesControls the CPU’s processing cycles Clock cycleClock cycle –Pulse or tick Clock speedClock speed –Number of pulses per second –Measured in hertz (Hz)

© 2008 Prentice-Hall, Inc. 15 The Control Unit Manages the switches inside the CPUManages the switches inside the CPU Is programmed by CPU designers to remember the sequence of processing stages for that CPUIs programmed by CPU designers to remember the sequence of processing stages for that CPU Moves each switch to its correct setting (on or off)Moves each switch to its correct setting (on or off) Then performs the work of that stageThen performs the work of that stage

© 2008 Prentice-Hall, Inc. 16 The Arithmetic Logic Unit (ALU) Part of the CPU designed to perform mathematical operations (addition, subtraction, multiplication, division, etc.)Part of the CPU designed to perform mathematical operations (addition, subtraction, multiplication, division, etc.) Also performs logical OR, AND, and NOT operationsAlso performs logical OR, AND, and NOT operations Is fed data from the CPU registersIs fed data from the CPU registers –Word size: Number of bits a computer can work with at a time

© 2008 Prentice-Hall, Inc. 17 Cache Memory Small amount of memory located on the CPU chip or near itSmall amount of memory located on the CPU chip or near it Stores recent or frequently used instructions and dataStores recent or frequently used instructions and data Used for quick access by the CPUUsed for quick access by the CPU Different levels of cacheDifferent levels of cache

© 2008 Prentice-Hall, Inc. 18 Cache Memory Different levels of cacheDifferent levels of cache –Level 1 Cache A block of memory that is built onto the CPU chip for the storage of data or commands that have just been used.A block of memory that is built onto the CPU chip for the storage of data or commands that have just been used. Level 2 cache is located on the CPU chip but is slightly farther away from the CPU, or it’s on a separate chip next to the CPULevel 2 cache is located on the CPU chip but is slightly farther away from the CPU, or it’s on a separate chip next to the CPU Some newer CPUs have an additional third level of cache memory storage called Level 3 cache.Some newer CPUs have an additional third level of cache memory storage called Level 3 cache.

© 2008 Prentice-Hall, Inc. 19 RAM: The Next Level of Temporary Storage Volatile: When you turn off your computer, the data stored in RAM is erasedVolatile: When you turn off your computer, the data stored in RAM is erased Several kinds of RAM existSeveral kinds of RAM exist Each type of RAM has a different designEach type of RAM has a different design –Some types work at much faster speeds –Some transfer data more quickly

© 2008 Prentice-Hall, Inc. 20 Types of RAM: DRAM Dynamic RAM (DRAM)Dynamic RAM (DRAM) –Cheapest and most basic type of RAM –Loses its electrical charge –Needs to be refreshed –Many types of DRAM SDRAM: Synchronous DRAMSDRAM: Synchronous DRAM –Faster than traditional DRAM DDR SDRAM: Double the data rate SDRAMDDR SDRAM: Double the data rate SDRAM

© 2008 Prentice-Hall, Inc. 21 Types of RAM: SRAM Static RAM (SRAM)Static RAM (SRAM) –Does not lose its electrical charge –Faster than DRAM –More expensive than DRAM –Used only in locations like cache memory where the system demands the fastest possible storage

© 2008 Prentice-Hall, Inc. 22 BusBus –Electrical pathway used to move data between components –Local bus: Connects the CPU with the memory –Expansion bus: Connects the CPU with peripheral devices Buses: The CPU’s Data Highway

© 2008 Prentice-Hall, Inc. 23 Bus Performance Bus clock speedBus clock speed –Rate of speed data moves from one location to another –Measured in MHz (millions of clock cycles per second) Bus widthBus width –The number of bits of data moved on a bus at any one time –Measured in bits 16 bits16 bits 32 bits32 bits

© 2008 Prentice-Hall, Inc. 24 Types of Expansion Buses ISA and EISAISA and EISA –Found on older computers –Connects mouse, modem, and sound card PCIPCI –Faster than ISA and EISA –Found on modern computers –Connects network, modem, and sound cards AGPAGP –Used for three-dimensional graphics –Connects the graphics card and memory

© 2008 Prentice-Hall, Inc. 25 Moore’s Law Number of transistors on a CPU will double every 18 monthsNumber of transistors on a CPU will double every 18 months First chip had 29,000 transistorsFirst chip had 29,000 transistors Pentium chip 169,000,000 transistorsPentium chip 169,000,000 transistors Moore’s Law has been accurate for more than 40 yearsMoore’s Law has been accurate for more than 40 years Law has remained accurate into the 21st centuryLaw has remained accurate into the 21st century

© 2008 Prentice-Hall, Inc. 26 Making Computers Faster As an instruction is processed, the CPU runs through the four stages of processing in a sequential order:As an instruction is processed, the CPU runs through the four stages of processing in a sequential order: –Fetch –Decode –Execute –Store.

© 2008 Prentice-Hall, Inc. 27 Making Computers Faster PipeliningPipelining –A technique that allows the CPU to work on more than one instruction (or stage of processing) at a time, thereby boosting CPU performance. –Used in some fashion in all modern CPUs.

© 2008 Prentice-Hall, Inc. 28 Making Computers Faster Pipelining Instead of the CPU carrying out one step of the machine cycle on every pulse of the system clock, the CPU performs different parts of the cycle simultaneously, theoretically making the CPU four times faster.Instead of the CPU carrying out one step of the machine cycle on every pulse of the system clock, the CPU performs different parts of the cycle simultaneously, theoretically making the CPU four times faster.

© 2008 Prentice-Hall, Inc. 29 Making Computers Faster Pipelining Chip makers have also designed special instruction sets to handle multimedia content, again speeding up the overall performance of the system.Chip makers have also designed special instruction sets to handle multimedia content, again speeding up the overall performance of the system.

© 2008 Prentice-Hall, Inc. 30 Making Computers Faster Pipelining: The CPU processes more than one instruction at a timePipelining: The CPU processes more than one instruction at a time FetchDecodeExecuteStore FetchDecodeExecuteStore Instruction 1 Instruction 2 Nonpipelined CPU FetchDecodeExecuteStore FetchDecodeExecuteStore FetchDecodeExecuteStore FetchDecodeExecuteStore Instruction 1 Instruction 2 Instruction 3 Instruction 4 Pipelined CPU

© 2008 Prentice-Hall, Inc. 31 Making Computers Faster Dual processingDual processing –Two CPUs on the same system –Each processor shares the workload Parallel processingParallel processing –Network of computers –Each computer works on a portion of the problem simultaneously Dual processors

© 2008 Prentice-Hall, Inc. 32 Dual-core Processing and Hyperthreading Two separate parallel processing pathsTwo separate parallel processing paths Almost as fast as two separate processorsAlmost as fast as two separate processors Hyperthreading allows the processor to run four tasks at onceHyperthreading allows the processor to run four tasks at once Allows multiple applications to execute much more quicklyAllows multiple applications to execute much more quickly

© 2008 Prentice-Hall, Inc. 33 Computing Clusters Group of computersGroup of computers –Allows computers to share computational tasks Connected by “clustering software”Connected by “clustering software” Load-balancing principleLoad-balancing principle –Allows a busy computer in the cluster to pass off the instruction to a computer with unused resources Not as fast as supercomputersNot as fast as supercomputers

© 2008 Prentice-Hall, Inc. 34 Computing Clusters Can be set up on Linux systems for freeCan be set up on Linux systems for free

© 2008 Prentice-Hall, Inc. 35 Chapter 9 Summary Questions What is a switch and how does it work in a computer?What is a switch and how does it work in a computer?

© 2008 Prentice-Hall, Inc. 36 Chapter 9 Summary Questions What is the binary number system and what role does it play in computer system?What is the binary number system and what role does it play in computer system?

© 2008 Prentice-Hall, Inc. 37 Chapter 9 Summary Questions What is inside the CPU and how do these components operate?What is inside the CPU and how do these components operate?

© 2008 Prentice-Hall, Inc. 38 Chapter 9 Summary Questions How does a CPU process data and instructions?How does a CPU process data and instructions?

© 2008 Prentice-Hall, Inc. 39 Chapter 9 Summary Questions What is cache memory?What is cache memory?

© 2008 Prentice-Hall, Inc. 40 Chapter 9 Summary Questions What types of RAM are there?What types of RAM are there?

© 2008 Prentice-Hall, Inc. 41 Chapter 9 Summary Questions What is a bus and how does it function in a computer system?What is a bus and how does it function in a computer system?

© 2008 Prentice-Hall, Inc. 42 Chapter 9 Summary Questions How do manufacturers make CPUs so that they run faster?How do manufacturers make CPUs so that they run faster?