Review For Final Fall 2008 Abdou Illia 1

Review For Final (Fall 2008) © Abdou Illia 1

Computer Hardware 2

The Core Computer Components p Three subsystems in a computer system: 1. Input subsystem 2. Processing subsystem 3. Output subsystem 3

Output Devices p Monitors n n n Cathode ray tube (CRTs) Liquid crystal displays (LCDs) Quality of display p p Resolution in pixels (e. g. 640 x 480) Dot pitch in millimeters (. 26 to. 28) Active-Matrix vs. Passive-Matrix display Touch screens n Input and output via display device Monitor size Common resolution 15 inches 640 x 480 17 inches 800 x 600 or 1024 x 768 19 inches 1024 x 768 or 1280 x 1024 4

Printers p Speed and resolution n n Pages per minute (PPM) Dots per inch (DPI) p p p Impact printers n n p Number of ink dots to fill a square inch Higher DPI = greater page clarity Create image by striking paper and ribbon Dot-matrix printers = most common impact printers Non-impact printers n Create image by spraying or rolling ink on the page 5

I/O devices or Secondary Storage p p Nonvolatile storage of digital data Magnetic or optical p Magnetic storage (Floppy disk, Magnetic tape, Zip disk, Hard disk) n n Sequential access (tape) or direct access (HDD) Hard disk drives p Two main standards: § IDE (Integrated Drive Electronics) aka ATA (AT Attachment) § SCSI (Small Computer System Interface) p p SCSI allows disk fault-tolerance through RAID – Redundant Array of Inexpensive Disks Disk speed: § Transfer rate in MBps (Megabytes per second) § Average Read Time (in milliseconds or ms) § Platter rotation speed in RPM (5400/7200/10, 000/15, 000) 6

Measuring Storage Capacity 7

Processing subsystem p Two major components CPU (Central Processing Unit) or Processor(s) p Primary Storage: p § Random Access Memory (RAM) § Read Only Memory (ROM) CPU Busses that transfer data Primary Storage 8

Central Processing Unit Processor p Clock: generate time that synchronize other components p ICU: Fetches instructions from RAM p ALU: Execute instructions (arithmetic & logic operations) p Registers: Store control information, data, intermediate results Clock Instruction Control Unit Registers Arithmetic Logic Unit 9

CPU speed p Speed measured in hertz n n n Hertz = # of instructions executed per second Megahertz = 1 million of instructions per second Gigahertz = 1 billion of instructions per second Major Processor manufacturers Intel - Celeron - Pentium 3, Pentium 4 Xeon, Dual Core Advanced Micro Devices (AMD) - K 6 series processors (which compete with Intel Pentium 3) - Athlon series (which compete with Intel Pentium 4) IBM - Power. PC 740, 750 FX, 750 GL, 750 GX 10

Primary Storage p Computer’s memory stored on semiconductor chips p Two categories: p RAM (Random Access Memory) which is volatile § Synchronous Dynamic RAM (SDRAM) § Double Data Rate SDRAM or DDR SDRAM p ROM (Read-Only Memory) which is non-volatile p Capacity in Megabytes (MB) or Gigabytes (GB) Primary Storage RAM Program p RAM holds running programs and the data they use p ROM contains critical programs such as those that boot the computer Data ROM 11

Summary Questions Book Notes 1) Name two devices that could be used for both input and output. 2) What is the difference between: (a) a Kilobyte and a Gigabyte? (b) a Megabyte and a byte? 3) What is the function of the Instruction Control Unit or ICU found in the processing subsystem? 4) Explain the difference between RAM and ROM. 5) What is pixel? What is dot pitch 6) What is a byte? 7) What is a Hertz? 12

Network Technology 13

Computer Network p Once connected to the network, the computer (or another device) becomes a network node An interconnection of computers and computing equipment using either wires or radio waves over small or large geographic distances GHI DEF ABC MNO “Connect to GHI” JKL 14

Physical Transmission Media p Physical media n n n Wireless Transmission media used to physically connect nodes in to the network Transmits electrical or optical signals Could be cooper wire or fiber optic cable 15

Transmission Media (Continued) p Twisted Pair Category Use Signal Data rate Distance Problem Category 1 Telephone Analog/Digital <100 Kbps 3 -4 miles Security, noise Category 2 T 1, ISDN Digital <2 Mbps 3 -4 miles Security, noise Category 3 LANs Digital 10 Mbps 100 m Security, noise Category 4 LANs Digital 20 Mbps 100 m Security, noise Category 5 LANs Digital 100 Mhz 100 m Security, noise Category 6 LANs Digital 250 Mhz 100 m Security, noise Category 7 LANs Digital 600 Mhz 100 m Security, noise 16

Wireless Media p p p Uses electromagnetic waves or electromagnetic radiation for data transmission Propagation through space, and indirectly, through solid objects Two kinds of wireless media used n Radio waves (radio Frequency) n Infrared light § § Affected by Multipath interference Highly vulnerable to snooping Limited distance Blocked by thick objects § Close proximity and “line of sight” location required Laptop Comm. Tower 17

Network Topologies p The configurations of network components n n p How physically the network looks like How logically data is transferred on the network Widely used network topologies: n n n Bus Star Ring 18

Network Architecture p Defines how the processing takes place on the network p Two primary types n n Client-server Peer-to-peer (P 2 P) 19

Protocols p p An agreed upon set of rules that govern communications in a network Example: TCP/IP suite, Ethernet, Token Ring Computer 1 Computer 2 Rules for Task 1 Rules for Task 2 Rules for Task 3 Rules for Task 4 Rules for Task 5 20

TCP/IP suite is named after its two main protocols: TCP and IP Transmission Control Protocol (TCP) p p Provides a reliable byte-stream transfer service between two endpoints on an internet n Internet Protocol (IP) p Defines a delivery mechanism for packets of data sent between all systems on an Internet n p It’s the protocol suite for the Internet Task Sample rules/protocols Application HTTP, FTP, SMTP Transport TCP, UDP Internet IP Physical Ethernet, Token Ring, PPP, Modem standards 21

Ethernet p p A set of rules for transmitting messages in LANs Most widely used protocol for LANs Uses a method called CSMA/CD* for wired LANs Set rules to handle collisions CSMA/CD* 1) 2) 3) 4) All computers (“carriers”) listen (“sense”) for traffic on the LAN If no traffic, computer that wishes to transmit may transmit If collision occurs, computers must wait a random amount of time The computer with smallest random number send again first. * Carrier Sense Multiple Access with Collision Detection 22

Token Ring p p Other set of rules for transmitting messages in LANs Only one node “talks” at a time p A node only transmit when it receives a special packet called a “Token” p Only one Token on the ring No collisions p 23

Summary Questions Malaga Notes 1) What is a node? 2) Name physical and wireless media used in networking 3) What transmission media is used for the telephone? 4) What are the main network topology? What are the differences between them? 5) Distinguish between Client-server and P 2 P networks 6) Could collisions occur in Token Ring networks? In Ethernet networks? 7) What is TCP/IP? 24