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Computer Architecture. How Does a Computer Work? Chapter 6. Student Learning Outcomes. Identify the system unit as well as the motherboard with its components. Define ASCII and describe how information is represented inside a computer.
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Computer Architecture How Does a Computer Work? Chapter 6
Student Learning Outcomes • Identify the system unit as well as the motherboard with its components. • Define ASCII and describe how information is represented inside a computer. • Describe the role of the CPU, RAM, and CPU cycles in the functioning of a computer. • Define and explain the role of connectors, ports, expansion buses, expansion cards, and expansion slots. • Describe how you connect external devices to your computer. ©2003 The McGraw-Hill Companies
Introduction At one of the spectrum a computer can be as big as a giant warehouse such as the Cray X1. At the other end of the spectrum is a tiny computer the size of a credit card being developed by Sharp. No matter how big or small computers are, they all have certain characteristics in common. ©2003 The McGraw-Hill Companies
System Unit • System unit is the case or box in which the motherboard and storage units are housed p. 6.162 Fig. 6-1 ©2003 The McGraw-Hill Companies
6.1 The Big Picture Input Data Process Data Output Information ©2003 The McGraw-Hill Companies
The System Unit • Motherboard is the large circuit board inside your system unit that holds the CPU, memory, and other essential electronic components • CAN YOU NAME THE PARTS? • SimNet Concepts Support CD: “The Motherboard” and “Inside the Computer” p. 6.164 Fig. 6.3 ©2003 The McGraw-Hill Companies
Port – Place through which information and instructions flow to your computer system Connector - plug used to connect a device to a computer CPU –Chip that carries out instructions it receives from the software RAM – Temporary memory that holds software instructions and information for the CPU System Unit Terminology ©2003 The McGraw-Hill Companies
Expansion Slot – socket on the motherboard into which an expansion card is inserted Expansion Card – Circuit board that is inserted into an expansion slot Expansion Bus – highway system that moves information coming from & going to devices outside the motherboard System Unit Terminology ©2003 The McGraw-Hill Companies
6.2 Representing Information Inside a Computer • Binary digit (bit) has two states - 0 or 1 • By combining bits into groups of 8, we can represent letters, symbols, and numbers, like the word "cool" (below) • A group of 8 bits represents one natural language character and is called abyte ©2003 The McGraw-Hill Companies
ASCII, EBCIDIC, and Unicode • ASCII—AmericanStandardCodeforInformationInterchange • Used on personal computers; eight-bit coding system; 256 different patterns • EBCDIC—ExtendedBinaryCodedDecimalInterchangeCode • Used by IBM mainframes; eight-bit coding system; 256 different patterns • Unicode—coding scheme capable of representing many languages • Usable on many computers; 16-bit coding system; approximately 65,000 patterns • SimNet Concepts Support CD: “Data Representation Using Binary Codes” ©2003 The McGraw-Hill Companies
ASCII & EBCDIC Binary Representations p. 6.168 Fig. 6.7 ©2003 The McGraw-Hill Companies
6.3 CPU, RAM, and Machine Cycles • Central processing unit (CPU or microprocessor or processor). Chip that carries out instructions it receives from your software • Random access memory (RAM) Temporary memory that holds software instructions and information for the CPU • Machine cycle (CPU cycle or clock cycle) consists of retrieving, decoding, and executing the instruction, and returning the result to RAM ©2003 The McGraw-Hill Companies
Central Processing Unit Chip that carries out instructions it receives from your software Role of the CPU is analogous to the role of your brain – keeps everything functioning as it’s supposed to • SimNet Concepts Support CD: “The CPU” p. 6.169 Fig. 6.3 ©2003 The McGraw-Hill Companies
Work being created Application Software instructions Keyboard Strokes & Mouse Movements Random Access Memory (RAM) OS Instructions RAM Holds ©2003 The McGraw-Hill Companies
1. Retrieve an instruction from RAM Machine cycle consists of: 4. Store the result In RAM 3. Execute the instruction 2. Decode the instruction Machine Cycle (CPU Cycle) ©2003 The McGraw-Hill Companies
How a CPU Works p. 6.170 Fig. 6.9 ©2003 The McGraw-Hill Companies
CPU Clock • Sliver of quartz that beats at regular intervals in response to an electrical charge • CPU clock keeps all the computer’s operations synchronized • Each tick of the CPU clock is called a clock cycle and is equivalent to a CPU cycle (machine cycle) • CPU uses the CPU clock to keep instructions and information flowing through your CPU at a fixed rate • SimNet Concepts Support CD: “System Clock” ©2003 The McGraw-Hill Companies
CPU Clock Each beat or tick of the clock is called a CPU cycle/machine cycle CPU speed is quoted in Megahertz (MHz = 1 million CPU cycles per second) or Gigahertz (GHz= 1 billiion CPU cycles per second). ©2003 The McGraw-Hill Companies
Central Processing Unit • The faster a CPU is, the more heat it generates • A heat sink and a fan are necessary to cool the CPU down CPU Cooling fan CPU Heat Sink p. 6.172 Fig. 6.11 ©2003 The McGraw-Hill Companies
Classes of CPU’s • Intel and AMD are two major manufacturers of CPUs for consumer computers • CPU speed and power continue to get faster • Higher-performance CPUs have top speeds and are the most expensive ©2003 The McGraw-Hill Companies
RAM Capacity • “Buy as much as you can afford”. For optimal performance purchase, more than the minimum specifications • 512 MB is standard on new computers – i.e. 512 million bytes • SimNet Concepts Support CD: “Memory” p.6.173 Fig. 6.13 ©2003 The McGraw-Hill Companies
Byte Kilobyte (KB) Megabytes (MB) Gigabytes (GB) Terabytes (TB) Petabyte (PB) Exabyte (EB) = 8 bits ≈1 Thousand Bytes ≈ 1 Million Bytes ≈1 Billion Bytes ≈1 Trillion Bytes ≈1 quadrillion Bytes ≈1 quintillion Bytes RAM Capacity: How Much Do You Need? ©2003 The McGraw-Hill Companies
RAM and Virtual Memory • If your computer runs out of physical RAM space, it uses hard disk space as temporary RAM, which is called virtual memory • Virtual memory is slower than physical RAM because instructions temporarily stored on the hard disk must be moved into RAM as they are needed ©2003 The McGraw-Hill Companies
How Virtual RAM Works p.6.174 Fig. 6.14 ©2003 The McGraw-Hill Companies
6.4 Making Connections • Portsare places in a computer system where external devices are plugged in, and through which information and instructions flow into the computer system • Connectorsconsist of cables that are used to join peripheral to the computer. Common types of connectors: • USB • Firewire • Serial • PS/2 • Parallel • RJ-45 p.6.175 Fig. 6.15 ©2003 The McGraw-Hill Companies
USB Connectors and Ports • USB (Universal serial bus) connector – is a plug-and-play interface between a computer and add-on device • With plug and play, a new device can be added to your computer without having to add an adapter card or even having to turn the computer off ©2003 The McGraw-Hill Companies
Firewire (IEEE 1394) • Firewire (IEEE1394) although different from USB, allows you to connect hot-swap, plug and play devices to your computer • Firewire used mostly for video camcorders and digital video disk (DVD) players • A popular implementation of IEEE 1394 is Sony’s I-LINK ©2003 The McGraw-Hill Companies
Serial Connectors and Ports • Serial means one event at a time. It is usually contrasted with parallel, meaning more than one event happening at a time • In the context of computer hardware and data transmission, serial connection, operation, and media usually indicate a simpler, slower operation and parallel indicates a faster operation ©2003 The McGraw-Hill Companies
Parallel Connectors and Ports • On a PC, the printer is usually attached through a parallel interface and cable so that it will print faster • Keyboard and mouse are one-way devices that only require a serial interface and line • SimNet Concepts Support CD: “Ports and Cables” ©2003 The McGraw-Hill Companies
Wireless Ports • Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communications path ©2003 The McGraw-Hill Companies
Wireless Ports – Cont. • Common examples of wireless equipment • Cellular phones • Global positioning systems • Cordless mouse • Wireless networks • Baby monitors • TV remote controls p.6.178 Fig. 6.17 ©2003 The McGraw-Hill Companies
Wireless Ports • IrDA (Infrared Data Association) port • Use infrared light to send and receive information • Bluetooth uses radio waves over distances of up to 30 feet ©2003 The McGraw-Hill Companies
IrDA (Infrared Data Association) • In this form of radio transmission, a focused ray of light in the infrared frequency spectrum, measured in terahertz, or trillions of hertz (cycles per second), is modulated and sent from a relatively short distance • IrDa communications is playing an important role in wireless data communication due to the popularity of laptop computers, personal digital assistants, digital cameras, mobile telephones, pagers, and other devices ©2003 The McGraw-Hill Companies
Examples for Using IrDA • Exchange business cards between handheld PCs • Send a document from a notebook computer to a printer • Coordinate schedules and telephone books between a desktop and notebook computer ©2003 The McGraw-Hill Companies
Examples for Using IrDA • Send faxes from a notebook computer to a distant fax machine through a public telephone • Beaming images from a digital camera into a computer • Interconnecting local area networks. Maximum effective distance is somewhat under 1.5 miles ©2003 The McGraw-Hill Companies
Bluetooth • Bluetooth is a computing and telecommunications industry specification that describes how mobile phones, computers, and PDAs can easily interconnect with each other and with home and business phones and computers using a short-range wireless connection • Bluetooth requires that a low-cost transceiver chip be included in each device ©2003 The McGraw-Hill Companies
Expansion Slots on the Motherboard • SimNet Concepts Support CD: “Expansion Cards and Slots” ©2003 The McGraw-Hill Companies
Buses • Data buses • Carries information in the form of bits around the motherboard • Two types: system and expansion • System bus • Electrical pathways which move information between RAM and CPU • The more bits that can travel together at one time, the faster the bus ©2003 The McGraw-Hill Companies
Expansion Bus • Moves information coming from and going to devices outside the motherboard • Types of expansion buses • ISA (industry standard architecture) • PCI (peripheral component interconnect) • AGP (accelerated graphics port) ©2003 The McGraw-Hill Companies
PCI and AGP Busses p.6.180 Fig. 6.19 ©2003 The McGraw-Hill Companies
6.5 Notebook Computers • Notebook computer is smaller and power to run devices is limited • Biggest advantage is its portability • Electronic engineers work to reduce the power and size requirements of these computers ©2003 The McGraw-Hill Companies
Notebook Computers CPUs and RAM • Notebook hardware has special features • A mobile CPU is a special type of CPU for a notebook computer that changes speed, and therefore power consumption, in response to fluctuations in demand • The CPU fan comes on only when the CPU gets too hot • RAM for a notebook looks a little different from desktop RAM Notebook RAM Desktop RAM p. 6.181 Fig. 6.13 & 6.20 ©2003 The McGraw-Hill Companies
Notebook Computers – Expansion Cards and Slots • Devices are added to a notebook by sliding a PC card into the PC Card slot on the notebook, and connecting the device to the PC card • A PC Card is the expansion card used to add devices to notebook computers p.6.181 Fig. 6.21 ©2003 The McGraw-Hill Companies
6.6 Consumer Q&A • Why Does My USB Device Not Work Right in My USB Port? • How Long Can I Expect My Notebook Battery to Last? • How Do I Connect Multiple Devices to a USB or Firewire Port? ©2003 The McGraw-Hill Companies
Bit Bluetooth Byte Central processing unit Connector CPU cache Expansion bus Expansion card Expansion slot Gigahertz (GHz) IrDA Machine cycle Megahertz (MHz) Mobile CPU PC Card PC Card Slot 6.7 Key Terms ©2003 The McGraw-Hill Companies
Peripheral component interconnect (PCI) slot Port RAM System bus Virtual memory 6.7 Key Terms ©2003 The McGraw-Hill Companies
Review of Concepts • Working with Nibbles • What’s less than a byte? • Comparing CPUs to the Human Body • Can You Identify Ports and Components? • Where would a DVD burner plug in? ©2003 The McGraw-Hill Companies
Hands On ProjectsE-Commerce • Buying RAM • Is your software running slower than it should be? • Buying Devices with the Right Connectors • Buying Music • Get the best music from the Web ©2003 The McGraw-Hill Companies
Hands On ProjectsEthics, Security & Privacy • Business Computers Classify You as Profitable – or Not • Should they be able to? • They want good customers – can computers help find bad ones? ©2003 The McGraw-Hill Companies