CSCI-100 Introduction to Computing Hardware Part I.

CSCI-100CSCI-100Introduction to ComputingIntroduction to Computing

HardwareHardwarePart IPart I

© Prentice-Hall, Inc

Hardware: The Basic Components Hardware: The Basic Components of a Computerof a Computer

Four primary Four primary components:components: Input DevicesInput Devices ProcessorProcessor Output devicesOutput devices StorageStorage


The ProcessorThe Processor

Also called central processing unit (CPU)Also called central processing unit (CPU) Center of activity in the computerCenter of activity in the computer

Consists of electronic circuits Consists of electronic circuits • Interprets and executes program instructionsInterprets and executes program instructions• Communicates with input, output, and storage Communicates with input, output, and storage

devicesdevices

Actually transforms data into informationActually transforms data into information


Storage: Primary StorageStorage: Primary Storage

Used to temporarily hold dataUsed to temporarily hold data After it is retrieved from input device and After it is retrieved from input device and

before it is processedbefore it is processed After it is processed and before it is released After it is processed and before it is released

to output deviceto output device Temporary (volatile) storageTemporary (volatile) storage

Data in memory lost if power is lost or Data in memory lost if power is lost or program closedprogram closed

Primary MemoryPrimary Memory

Memory RAM (Memory RAM (RRandom andom AAccessccess M Memory)emory) ROM (Read Only Memory)ROM (Read Only Memory)


Storage: Secondary StorageStorage: Secondary Storage

Provides long-term storageProvides long-term storage Separate from memorySeparate from memory

Common mediaCommon media Magnetic disksMagnetic disks Optical disksOptical disks Magnetic tapeMagnetic tape


Magnetic DisksMagnetic Disks

The most common storage mediaThe most common storage media Diskette: 3.5” flexible diskette in plastic caseDiskette: 3.5” flexible diskette in plastic case Hard Disk: more storage capacity and faster Hard Disk: more storage capacity and faster

access than disketteaccess than diskette


Optical DisksOptical Disks

Use a laser beam to read large volumes of Use a laser beam to read large volumes of data inexpensivelydata inexpensively CD-ROMsCD-ROMs DVD-ROMsDVD-ROMs


Magnetic TapeMagnetic Tape

Stores large amounts of data Stores large amounts of data inexpensivelyinexpensively

Often used for system backupOften used for system backup


OFF

ON

0 1

OR = 1 bit

1

0

0 0 001 1

0 0 0 01 1

OR

= 1 Byte

= 1 Byte

OFF

0

0

How Computers Represent DataHow Computers Represent Data

BitBit (Binary digit) (Binary digit) –– On or off state of electric current; On or off state of electric current; considered the basic unit of information; represented by considered the basic unit of information; represented by 1s and 0s (binary numbers)1s and 0s (binary numbers)

ByteByte – Eight bits grouped together to represent a – Eight bits grouped together to represent a character (an alphabetical letter, a number, or a character (an alphabetical letter, a number, or a punctuation symbol); How many possible combinations?punctuation symbol); How many possible combinations?

ON


Bit BasicsBit Basics

A bit (binary digit)A bit (binary digit) Is the smallest unit of informationIs the smallest unit of information Can have two values: Can have two values: 1 or or 0 Can represent numbersCan represent numbers, , codescodes, ,

oror instructionsinstructions

On


Bits as CodesBits as Codes

ASCII – American Standard Code for Information Interchange

Most widely used code, represents each character as a unique 8-bit code


Bits as InstructionsBits as Instructions

The computer stores instructions as The computer stores instructions as collections of bits. For instance, collections of bits. For instance, 01101010 might instruct the computer to add two might instruct the computer to add two numbersnumbers

Other bit instructions might include where Other bit instructions might include where to find numbers stored in memory or to find numbers stored in memory or where to store themwhere to store them


8 bits = 1 Byte

1024 Bytes = 1 Kilobyte (KB)

1,048,576 Bytes = 1 Megabyte (MB)

1,043,741,824 Bytes = 1 Gigabyte (GB)

1,099,511,627,776 Bytes = 1 Terabyte (TB)

BytesBytes

KilobyteKilobyte, , megabytemegabyte, , gigabytegigabyte, and , and terabyteterabyte are terms that describe large units of data are terms that describe large units of data used in measuring data storage used in measuring data storage Example: 20 GB hard driveExample: 20 GB hard drive


Inside the System UnitInside the System Unit Motherboard Motherboard (mainboard) – Large (mainboard) – Large

printed circuit board with printed circuit board with thousands of electrical circuitsthousands of electrical circuits

Power supplyPower supply – Transforms – Transforms alternating current (AC) from wall alternating current (AC) from wall outlets to direct current (DC) outlets to direct current (DC) needed by the computerneeded by the computer

Cooling fanCooling fan – Keeps the system – Keeps the system unit coolunit cool

Internal SpeakerInternal Speaker – Used for beeps – Used for beeps when errors are encounteredwhen errors are encountered

Drive baysDrive bays – Housing for the – Housing for the computer’s hard drive, floppy drive, computer’s hard drive, floppy drive, and CD-ROM / DVD-ROM drivesand CD-ROM / DVD-ROM drives


The MotherboardThe Motherboard The motherboard The motherboard

provides the centralized provides the centralized connection point for the connection point for the computer’s componentscomputer’s components Most components are Most components are

integrated circuits integrated circuits (chips)(chips)

• ChipsChips carry electrical current carry electrical current and contain electronic and contain electronic switches or switches or transistorstransistors


The Central Processing Unit: The Central Processing Unit: The MicroprocessorThe Microprocessor

CPU

CPU socket

Central processing unit (Central processing unit (CPUCPU) – A microprocessor ) – A microprocessor that interprets and carries out instructions given by that interprets and carries out instructions given by software. It controls the computer’s componentssoftware. It controls the computer’s components


Components of the CPUComponents of the CPU

Control unitControl unit – Coordinates and controls all – Coordinates and controls all parts of the computer systemparts of the computer system

Arithmetic-logic unitArithmetic-logic unit – Performs arithmetic – Performs arithmetic or logical operationsor logical operations

RegistersRegisters – Temporarily store the most – Temporarily store the most frequently used instructions and datafrequently used instructions and data


The Control UnitThe Control Unit The The control unitcontrol unit manages four basic operations manages four basic operations

(fetch, decode, execute, and write-back)(fetch, decode, execute, and write-back) The four-step process is known as the The four-step process is known as the machine machine

cyclecycle or or processing cycleprocessing cycle The processing cycle consists of two phases:The processing cycle consists of two phases:

• Instruction Cycle Fetch – Gets the– Gets the next program instruction from the next program instruction from the

computer’s memorycomputer’s memory Decode – Figures out what the program is telling the – Figures out what the program is telling the

computer to docomputer to do

• Execution Cycle Execute – Performs the requested action – Performs the requested action Write-back (Store) – Writes (stores) the results to a register (Store) – Writes (stores) the results to a register

or to memoryor to memory


The Arithmetic-Logic UnitThe Arithmetic-Logic Unit

The arithmetic-logic unit ((ALUALU) performs ) performs basic arithmetic and logic operationsbasic arithmetic and logic operations Adds, subtracts, multiplies, and dividesAdds, subtracts, multiplies, and divides Compares alphanumeric dataCompares alphanumeric data

Arithmetic OperationArithmetic Operation

Example: Addition Example: Addition 0001110100011101 + 10001010+ 10001010 ---------------------------------- 1010011110100111


Logic OperationLogic Operation

A B A and B A or B not A

0 0 0 0 1

0 1 0 1 0

1 0 0 1

1 1 1 1


The Local BusThe Local Bus

The Bus is The Bus is the circuitry on the motherboard (the main the circuitry on the motherboard (the main

board that holds the microprocessor, memory, board that holds the microprocessor, memory, and adapter cards) that provides a path for and adapter cards) that provides a path for which data travels from one component to which data travels from one component to another.another.

The Local BusThe Local Bus

Today’s PCs have multiple local busesToday’s PCs have multiple local buses each Bus is 32bits wide and travels as fast as each Bus is 32bits wide and travels as fast as

the microprocessor. the microprocessor. each Bus is connected to a specific device each Bus is connected to a specific device

and does not have to share it with other and does not have to share it with other components.components.

PCI - A bus designed by Intel for the Pentium PCI - A bus designed by Intel for the Pentium or Pentium Pro.or Pentium Pro.

CSCI-100 Introduction to Computing Hardware Part I.

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