today’s topics chapter 6: system unit chapter 7: input/output and storage

Today’s TopicsToday’s Topics

Chapter 6: System UnitChapter 6: System Unit Chapter 7: Input/Output and StorageChapter 7: Input/Output and Storage

Chapter 6Chapter 6System UnitSystem Unit

How Computers Represent DataHow Computers Represent Data

Bit (Binary Digit): smallest unit of information that Bit (Binary Digit): smallest unit of information that a computer can work with (0 or 1)a computer can work with (0 or 1) Kilobits Per Second (Kbps) = 125 charactersKilobits Per Second (Kbps) = 125 characters Megabits Per Second (Mbps) = 125 pagesMegabits Per Second (Mbps) = 125 pages Gigabits Per Second (Gbps) = 125,000 pagesGigabits Per Second (Gbps) = 125,000 pages

Byte: one unit of storage consisting of 8 bitsByte: one unit of storage consisting of 8 bits Kilobyte (K or KB) = 1 pageKilobyte (K or KB) = 1 page Megabyte (M or MB) = 1,000 pagesMegabyte (M or MB) = 1,000 pages Gigabyte (G or GB) = 1,000 booksGigabyte (G or GB) = 1,000 books Terabyte (T or TB) = 1 million booksTerabyte (T or TB) = 1 million books

Decimal Number SystemDecimal Number System

6 = (6 x 10^0)6 = (6 x 10^0) 45 = (4 x 10^1) + (5 x 10^0) = 40 + 545 = (4 x 10^1) + (5 x 10^0) = 40 + 5 214 = (2 x 10^2) + (1 x 10^1) + (4 x 10^0) 214 = (2 x 10^2) + (1 x 10^1) + (4 x 10^0)

= 200 + 10 + 4= 200 + 10 + 4

Binary to Decimal ConversionBinary to Decimal Conversion

0 = (0 x 2^0) = 00 = (0 x 2^0) = 0 1 = (1 x 2^0) = 11 = (1 x 2^0) = 1 10 = (1 x 2^1) + (0 x 2^0) = 2 + 0 = 210 = (1 x 2^1) + (0 x 2^0) = 2 + 0 = 2 11 = 11 =

(1 x 2^1) + (1 x 2^0) = 2 + 1 = 3(1 x 2^1) + (1 x 2^0) = 2 + 1 = 3 101011 = 101011 =

(1 x 2^5) + (0 x 2^4) + (1 x 2^3) + (0 x 2^2) + (1 x 2^5) + (0 x 2^4) + (1 x 2^3) + (0 x 2^2) + (1 x 2^1) + (1 x 2^0) = 32 + 0 + 8 + 0 + 2 + 1 = (1 x 2^1) + (1 x 2^0) = 32 + 0 + 8 + 0 + 2 + 1 = 4343

Decimal to Binary ConversionDecimal to Binary Conversion

2^7 2^6 2^5 2^4 2^3 2^2 2^1 2^0 =2^7 2^6 2^5 2^4 2^3 2^2 2^1 2^0 = 128 64 32 16 8 4 2 1128 64 32 16 8 4 2 1 To convert a decimal number to binary, To convert a decimal number to binary,

first subtract the largest possible power of first subtract the largest possible power of two, and keep subtracting the next largest two, and keep subtracting the next largest possible power from the remainder, possible power from the remainder, marking 1s in each position where this is marking 1s in each position where this is possible and 0s where it is not. possible and 0s where it is not.

Decimal to Binary ConversionDecimal to Binary Conversion

2^7 2^6 2^5 2^4 2^3 2^2 2^1 2^0 =2^7 2^6 2^5 2^4 2^3 2^2 2^1 2^0 = 128 64 32 16 8 4 2 1 =128 64 32 16 8 4 2 1 = 0 0 1 1 0 1 1 10 0 1 1 0 1 1 1 5555 - 32 = 23 - 32 = 23 23 - 16 = 723 - 16 = 7 7 - 4 = 37 - 4 = 3 3 - 2 = 13 - 2 = 1 1 - 1 = 01 - 1 = 0

Character CodeCharacter Code

American Standard Code for Information American Standard Code for Information Interchange (ASCII): used for the InternetInterchange (ASCII): used for the Internet

Extended Binary Coded Decimal Extended Binary Coded Decimal Interchange Code (EBCDIC): used on IBM Interchange Code (EBCDIC): used on IBM mainframemainframe

Unicode: represents many foreign Unicode: represents many foreign languageslanguages

CPU SubcomponentsCPU Subcomponents

Control Unit: extracts instructions from memory Control Unit: extracts instructions from memory and decodes and executes themand decodes and executes them Machine Cycle or Processing CycleMachine Cycle or Processing Cycle

Instruction CycleInstruction Cycle Fetch: retrieves the next program instruction from memoryFetch: retrieves the next program instruction from memory Decode: determines what the program is telling the computer to Decode: determines what the program is telling the computer to

dodo Execution CycleExecution Cycle

Execute: performs the requested instructionExecute: performs the requested instruction Store: stores the results to an register or memoryStore: stores the results to an register or memory

Registers: Temporary Storage Locations in CPURegisters: Temporary Storage Locations in CPU Arithmetic-Logic UnitArithmetic-Logic Unit

CPU PerformanceCPU Performance

Data Bus: highway of parallel wires Data Bus: highway of parallel wires connecting CPU internal componentsconnecting CPU internal components

Word Size: maximum number of bits the Word Size: maximum number of bits the CPU can process at onceCPU can process at once

System Clock: electronic circuit that System Clock: electronic circuit that generates pulses at a rapid rate and generates pulses at a rapid rate and synchronizes the computer’s internal synchronizes the computer’s internal activities (GHz)activities (GHz)

Techniques to Improve CPU Techniques to Improve CPU PerformancePerformance

Superscalar Architecture: design of CPU Superscalar Architecture: design of CPU that can execute more than one instruction that can execute more than one instruction per clock cycleper clock cycle

Pipelining: processing technique that Pipelining: processing technique that feeds a new Instruction into CPU at every feeds a new Instruction into CPU at every step of processing cyclestep of processing cycle

Data Dependency: result of a completed Data Dependency: result of a completed instruction to process the next oneinstruction to process the next one


Speculative Execution: processor executes and Speculative Execution: processor executes and temporarily stores the next instruction in case it temporarily stores the next instruction in case it proves usefulproves useful

Branch Prediction: processor tries to predict Branch Prediction: processor tries to predict what will likely happenwhat will likely happen

Example: IF A = B THEN Example: IF A = B THEN C = C + 1 C = C + 1

ELSE ELSE C = C - 1 C = C - 1

END IF END IF


Parallel Processing: technique that uses Parallel Processing: technique that uses more than one processor running more than one processor running simultaneouslysimultaneously

MemoryMemory

Memory: chips that enable the computer to Memory: chips that enable the computer to retain informationretain information Random Access Memory (RAM): stores Random Access Memory (RAM): stores

information temporarilyinformation temporarily Read-Only Memory (ROM): prerecords Read-Only Memory (ROM): prerecords

instructions to start the computer and cannot instructions to start the computer and cannot be erasedbe erased

Cache Memory: stores frequently or recently Cache Memory: stores frequently or recently accessed program instructions and dataaccessed program instructions and data

Chapter 7Chapter 7Input/ Output and StorageInput/ Output and Storage

Input DevicesInput Devices

KeyboardKeyboard Insertion Point: the location of the cursor that Insertion Point: the location of the cursor that

shows where text will appear when you typeshows where text will appear when you type Toggle Key: the key that has only two Toggle Key: the key that has only two

positions which are on and offpositions which are on and off Example: Caps Lock KeyExample: Caps Lock Key

Function Keys: keys that provide different Function Keys: keys that provide different commands, depending on the program in usecommands, depending on the program in use http://www.compukiss.com/sandyclassroom/tutorialhttp://www.compukiss.com/sandyclassroom/tutorial

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KeyboardKeyboard Modifier Keys: the keys that have no effect unless Modifier Keys: the keys that have no effect unless

holding them down and pressing a second keyholding them down and pressing a second key Ctrl + ACtrl + A Ctrl + XCtrl + X Ctrl + CCtrl + C Ctrl + VCtrl + V Ctrl + HomeCtrl + Home Ctrl + EndCtrl + End Window + DWindow + D


MouseMouse TrackballTrackball Pointing StickPointing Stick Touch Pad (Track Pad)Touch Pad (Track Pad) JoystrickJoystrick Touch ScreenTouch Screen Light PenLight Pen StylusStylus Microphone Microphone ScannerScanner Bar Code ReaderBar Code Reader

Output DevicesOutput Devices

MonitorMonitor Liquid Crystal Display (LCD) / Flat-Panel Liquid Crystal Display (LCD) / Flat-Panel

DisplayDisplay High Definition Television (HDTV)High Definition Television (HDTV) Screen SizeScreen Size Resolution: sharpness of an imageResolution: sharpness of an image Refresh Rate: frequency at which the screen Refresh Rate: frequency at which the screen

image is updated in Hzimage is updated in Hz

Output DevicesOutput Devices

PrinterPrinter Inkjet Printer (Bubble-Jet Printer)Inkjet Printer (Bubble-Jet Printer) Laser PrinterLaser Printer PlotterPlotter

ProjectorProjector

StorageStorage

RAM VS StorageRAM VS Storage Storage devices are non-volatile: retaining Storage devices are non-volatile: retaining

data when the current is switched offdata when the current is switched off Storage devices are cheaper than memoryStorage devices are cheaper than memory Storage devices are important in system Storage devices are important in system

startup operationsstartup operations Storage devices are needed for outputStorage devices are needed for output

StorageStorage

Hard Disk DriveHard Disk Drive File Allocation Table (FAT): File Allocation Table (FAT):

table that keeps track the table that keeps track the location of files in MS Windowslocation of files in MS Windows

Partition: section of a disk Partition: section of a disk enabling computers to work enabling computers to work with more than one OSwith more than one OS

Internet Hard Drive: storage Internet Hard Drive: storage space on a server that is space on a server that is accessible from the Internetaccessible from the Internet

StorageStorage

Floppy Disk: 1.44 MBFloppy Disk: 1.44 MB Zip Disk: 750 MBZip Disk: 750 MB CD-ROM/ CD-R/ CD-RW: 650 MBCD-ROM/ CD-R/ CD-RW: 650 MB DVD-ROM/ DVD-R/ DVD-RW: 17 GBDVD-ROM/ DVD-R/ DVD-RW: 17 GB FMD-ROM: 1 TBFMD-ROM: 1 TB Solid-State Storage DevicesSolid-State Storage Devices

PC Card (PCMCIA)PC Card (PCMCIA) Flash Memory CardFlash Memory Card Smart CardSmart Card

today’s topics chapter 6: system unit chapter 7: input/output and storage

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