Chapter 5: Computing Components Chapter 5 Computing Components Page 37 In the 1940s and 1950s, John...

Chapter 5: Computing Chapter 5: Computing ComponentsComponents

Chapter 5Chapter 5Computing Computing

ComponentsComponentsPage 1

In the 1940s and 1950s, In the 1940s and 1950s, John von Neumann John von Neumann helped develop the helped develop the architecture that architecture that

continues to be used in continues to be used in the design of most the design of most modern computer modern computer

systems.systems.

Control Control Unit, Unit,

CoordinaCoordinating CPU ting CPU ActivityActivity

ArithmetiArithmetic/c/

Logic Logic Unit, Unit,

ProcessiProcessing Datang Data

Central Processing Unit (CPU)Central Processing Unit (CPU)



Bus Interface UnitBus Interface UnitInformation from the Information from the RAM enters the CPU RAM enters the CPU here , and then it is here , and then it is

sent to separate sent to separate storage units or cachestorage units or cache

Code CacheCode CacheStorage for instructions for Storage for instructions for

deciphering datadeciphering data

Branch Predictor UnitBranch Predictor UnitDecides which ALU can best Decides which ALU can best

handle specific data & handle specific data & divides the tasksdivides the tasks

Instruction Prefetch Instruction Prefetch & Decoding Unit& Decoding UnitTranslates data into Translates data into

simple instructions for simple instructions for ALU to processALU to process

Arithmetic Logic Arithmetic Logic UnitUnit

Whole number Whole number crunchercruncher

Floating Point UnitFloating Point UnitFloating-point number Floating-point number

crunchercruncher

Instruction RegisterInstruction RegisterProvides the ALUs with Provides the ALUs with processing instructions processing instructions

from the data cachefrom the data cache

Data CacheData CacheSends data from ALUs to Sends data from ALUs to

Bus Interface Unit, and then Bus Interface Unit, and then back to RAMback to RAM

Simplified View of the CPUSimplified View of the CPU



CPUCPU

ALUALUCircuitry Circuitry

that that manipulatemanipulates the datas the data

RegisteRegistersrs

Special Special memory memory cells to cells to

temporarily temporarily store the store the

data being data being manipulatemanipulate

dd

Control Control UnitUnit

Circuitry to Circuitry to coordinate coordinate

the operation the operation of the of the

computercomputer

BusBus RAMRAM

The Processing CycleThe Processing Cycle



MAIN MEMORYMAIN MEMORY

CONTROL UNITCONTROL UNIT ARITHMETIC/LOGIC UNITARITHMETIC/LOGIC UNIT

DECODE DECODE instruction to instruction to

determine what determine what to doto do

FETCH the next FETCH the next instruction from instruction from

main memorymain memory

EXECUTE the EXECUTE the decoded decoded

instructioninstruction

STORE the STORE the result in result in

main main memorymemory

Sample Machine ArchitectureSample Machine Architecture



CPUCPU

ALUALUBus

RegistRegistersers

FFEEDDCCBBAA99887766554433221100

Control Control UnitUnit

Program Counter

(Keeps track of the address of

the next instruction to be executed)

Program Counter

(Keeps track of the address of

the next instruction to be executed)

Instruction Register(Contains a

copy of the 2-byte

instruction currently being

executed)

Instruction Register(Contains a

copy of the 2-byte

instruction currently being

executed)

Main Memory CellsMain Memory Cells

111110100F0F0E0E0D0D0C0C0B0B0A0A0909080807070606050504040303020201010000

FFFFFEFEFDFDFCFCFBFBFAFAF9F9F8F8F7F7F6F6F5F5F4F4F3F3F2F2F1F1F0F0EFEFEEEE

:: ::

:: ::

Random Access Memory (RAM)Random Access Memory (RAM)



• Whenever a computer accesses Whenever a computer accesses information (e.g., a program information (e.g., a program that’s being executed, data that’s being executed, data that’s being examined), that that’s being examined), that information is stored as information is stored as electronic pulses within electronic pulses within main main memorymemory..

• Main memory is a system of Main memory is a system of electronic circuits known as electronic circuits known as random access memoryrandom access memory (RAM), (RAM), the idea being that the user the idea being that the user can randomly access any part can randomly access any part of memory (as long as the of memory (as long as the location of what’s being location of what’s being accessed is known).accessed is known).

• The circuitry in main memory is The circuitry in main memory is usually usually dynamicdynamic RAM, meaning RAM, meaning that the binary values must be that the binary values must be continuously refreshed continuously refreshed (thousands of times per (thousands of times per second) or the charge will second) or the charge will dissipate and the values will be dissipate and the values will be lost.lost.

Cache MemoryCache Memory



• Due to the need for continuous Due to the need for continuous refreshing, dynamic RAM is refreshing, dynamic RAM is rather slow. An alternative rather slow. An alternative approach is approach is static RAMstatic RAM, which , which uses “flip-flop” circuitry that uses “flip-flop” circuitry that doesn’t waste time refreshing doesn’t waste time refreshing the stored binary values.the stored binary values.

• Static RAM is much faster than Static RAM is much faster than dynamic RAM, but is much more dynamic RAM, but is much more expensive. Consequently, it is expensive. Consequently, it is used less in most machines.used less in most machines.

• CacheCache memory uses static RAM memory uses static RAM as the first place to look for as the first place to look for information and as the place to information and as the place to store the information that was store the information that was most recently accessed (e.g., most recently accessed (e.g., the current program being the current program being executed).executed).

Magnetic MemoryMagnetic Memory



• When the power is turned off, When the power is turned off, a computer’s electronic a computer’s electronic memory devices immediately memory devices immediately lose their data. In order to lose their data. In order to store information on a store information on a computer when it’s turned off, computer when it’s turned off, some non-magnetic storage some non-magnetic storage capability is required.capability is required.

• Most computers contain Most computers contain hard hard drivesdrives, a system of magnetic , a system of magnetic platters and read-write heads platters and read-write heads that detect the polarity of the that detect the polarity of the magnetic filaments beneath magnetic filaments beneath them (i.e., “reading” the bit them (i.e., “reading” the bit values) and induce a values) and induce a magnetic field onto the magnetic field onto the filaments (i.e., “writing” the filaments (i.e., “writing” the bit values).bit values).

Disk Tracks and SectorsDisk Tracks and Sectors



• Each platter is divided Each platter is divided into concentric circles, into concentric circles, called called trackstracks, and each , and each track is divided into track is divided into wedges, called wedges, called sectorssectors..

• The read-write head The read-write head moves radially towards moves radially towards and away from the center and away from the center of the platter until it of the platter until it reaches the right track.reaches the right track.

• The disk spins around The disk spins around until the read-write head until the read-write head reaches the appropriate reaches the appropriate sector.sector.

Floppy DisksFloppy Disks



• Portable magnetic memory Portable magnetic memory devices, known as devices, known as floppy floppy disksdisks, have limited storage , have limited storage capacity, slow revolution capacity, slow revolution speeds, and long access speeds, and long access times, but they are easily times, but they are easily removed from a machine and removed from a machine and installed in another installed in another computer.computer.

Optical MemoryOptical Memory



• Compact Disks – Read-Only Compact Disks – Read-Only MemoryMemory (CD-ROMs) use pitted (CD-ROMs) use pitted disks and lasers to store disks and lasers to store binary information.binary information.

• When the laser hits an When the laser hits an unpitted “land”, light is unpitted “land”, light is reflected to a sensor and reflected to a sensor and interpreted as a 1-bit; when interpreted as a 1-bit; when the laser hits a pit, light isn’t the laser hits a pit, light isn’t reflected back, so it’s reflected back, so it’s interpreted as a 0-bit.interpreted as a 0-bit.

• Digital Versatile Digital Versatile DisksDisks (DVDs) (DVDs) use the same use the same pits-and-lands pits-and-lands approach as CD-approach as CD-ROMs, but with ROMs, but with finer gaps finer gaps between tracks between tracks and pits, and pits, resulting in over resulting in over four times the four times the storage capacity storage capacity as CD-ROMs.as CD-ROMs.

Flash MemoryFlash Memory



Universal Universal Serial Serial Bus Bus

(USB) (USB) ConnectoConnector to Host r to Host ComputeCompute

rr

USB Mass USB Mass Storage Storage

ControllerControllerTest Test

Points Points for for

VerifyiVerifying ng

Proper Proper LoadinLoadin

gg

Flash Flash Memory Memory

ChipChip

Crystal Crystal OscillatoOscillato

r to r to Produce Produce

Clock Clock SignalSignal

LEDs to LEDs to Indicate Indicate

Data Data TransferTransfer

ss

Write-Write-Protect Protect SwitchSwitch

Space for Space for Second Second Flash Flash

Memory Memory ChipChip

• Recent advances in Recent advances in memory circuitry have memory circuitry have made it possible to made it possible to develop portable develop portable electronic devices with electronic devices with large memory large memory capacities.capacities.

• Flash memory is Flash memory is Electrically Erasable Electrically Erasable Programmable Read-Programmable Read-Only Memory Only Memory (EEPROM):(EEPROM):• Read-Only Memory: Non-Read-Only Memory: Non-

volatile (retains data even volatile (retains data even after power is shut off), after power is shut off), but difficult to alter.but difficult to alter.

• Programmable: Programs Programmable: Programs aren’t added until after aren’t added until after the device is the device is manufactured, by manufactured, by “blowing” all fuses for “blowing” all fuses for which a 1-value is which a 1-value is desired.desired.

• Electrically Erasable: Electrically Erasable: Erasing is possible by Erasing is possible by applying high electric applying high electric fields.fields.

Input Device: KeyboardInput Device: Keyboard



One of the principal One of the principal devices for providing devices for providing input to a computer is the input to a computer is the keyboardkeyboard..

When a key is pressed, a When a key is pressed, a plunger on the bottom of plunger on the bottom of the key pushes down the key pushes down against a rubber dome…against a rubber dome…

……the center of which the center of which completes a circuit within completes a circuit within the keyboard, resulting in the keyboard, resulting in the CPU being signaled the CPU being signaled regarding which key (or regarding which key (or keys) has been pressed.keys) has been pressed.

Input Device: MouseInput Device: Mouse



Moving Moving the the

mouse mouse turns turns

the ballthe ball

X and Y X and Y rollers grip rollers grip

the ball the ball and and

transfer transfer movementmovement

Optical Optical encodinencoding disks g disks include include

light light holesholes

Infrared Infrared LEDs LEDs shine shine

through through the disksthe disks

Sensors Sensors gather gather light light

pulses to pulses to convert convert to X and to X and

Y Y velocitiesvelocities

The mouse The mouse driver driver

software software processes processes

the X and Y the X and Y data and data and

transfers it transfers it to the to the

operating operating systemsystem

The other primary input device is the The other primary input device is the computer computer mousemouse..

Mechanical MouseMechanical Mouse

Optical MouseOptical Mouse

Optical mice use red LEDs Optical mice use red LEDs (or lasers) to illuminate (or lasers) to illuminate the surface beneath the the surface beneath the

mouse, and sensors mouse, and sensors detect the subtle changes detect the subtle changes

that indicate how much that indicate how much and in what direction the and in what direction the mouse is being moved.mouse is being moved.

Output Device: Cathode Ray Output Device: Cathode Ray Tube (CRT)Tube (CRT)



Electron GunsElectron GunsA heating A heating filament filament releases releases

electrons from electrons from a cathode, a cathode, which flow which flow through a through a

control grid control grid (controlling (controlling brightness)brightness)

Focusing CoilFocusing CoilThe magnetic coil The magnetic coil

forces the electron forces the electron flows to focus into flows to focus into

tight beamstight beams

Deflection CoilsDeflection CoilsThese magnetic These magnetic

plates deflect the plates deflect the beams horizontally beams horizontally

and vertically to and vertically to particular screen particular screen

coordinatescoordinates Anode Anode ConnectionConnectionThe positive The positive

charge on the charge on the anode attracts anode attracts the electrons the electrons

and accelerates and accelerates them forwardsthem forwards

Shadow MaskShadow MaskA perforated metal A perforated metal sheet halts stray sheet halts stray

electrons and ensures electrons and ensures that beams focus upon that beams focus upon

target phosphorstarget phosphors

Phosphor-Coated Phosphor-Coated ScreenScreen

Each pixel is comprised Each pixel is comprised of a triad of RGB of a triad of RGB

phosphors that are phosphors that are illuminated by the illuminated by the

three electron beamsthree electron beams

Output Device: Liquid Crystal Output Device: Liquid Crystal DisplayDisplay



Light Light SourcSourc

ee

Horizontal Horizontal PolarizerPolarizer

Converts light into Converts light into horizontal shaftshorizontal shafts

Thin Film Thin Film TransistorTransistor

Applies charge Applies charge to individual to individual

subpixelsubpixel

Twisted Nematic Liquid Twisted Nematic Liquid CrystalsCrystals

Twists shaft of light 90º Twists shaft of light 90º when uncharged, 0º when uncharged, 0º when fully chargedwhen fully charged

Color FilterColor FilterProvides red, Provides red, green, or blue green, or blue

color to color to resulting lightresulting light

Vertical PolarizerVertical PolarizerAmount of light Amount of light

permitted to pass is permitted to pass is proportional to how proportional to how close to vertical its close to vertical its

shafts areshafts are

Output Device: Plasma DisplayOutput Device: Plasma Display



Front Plate Front Plate GlassGlass

Dielectric LayerDielectric LayerContains Contains

transparent transparent address address

electrodes, electrodes, arranged in arranged in

long horizontal long horizontal rowsrows

Rear Plate Rear Plate GlassGlass

Dielectric LayerDielectric LayerContains transparent display Contains transparent display electrodes, arranged in long electrodes, arranged in long

vertical columnsvertical columns

Plasma CellsPlasma CellsPhosphor coating is Phosphor coating is excited by plasma excited by plasma

ionization and ionization and photon releasephoton release

PixelPixelComprised of three Comprised of three plasma cells, one of plasma cells, one of each RGB phosphor each RGB phosphor

coatingcoating

Input/Output Device: Touch Input/Output Device: Touch ScreenScreen



CapacitiveCapacitiveSmall amounts Small amounts of voltage are of voltage are applied to the applied to the four corners of four corners of

the screen.the screen.Touching the Touching the screen draws screen draws current from current from each corner, each corner,

and a and a controller controller

measures the measures the ratio of the ratio of the

four currents four currents to determine to determine

the touch the touch location.location.

ResistiveResistiveThe glass layer The glass layer

has an outer has an outer coating of coating of conductive conductive

material, and material, and insulating dots insulating dots

separate it from a separate it from a flexible membrane flexible membrane

with an inner with an inner conductive conductive

coating.coating.When the screen When the screen is touched, the is touched, the two conductive two conductive materials meet, materials meet,

producing a producing a locatable voltage.locatable voltage.

InfraredInfraredA small frame is A small frame is placed around placed around

the display, the display, with infrared with infrared

LEDs and LEDs and photoreceptors photoreceptors

on opposite on opposite sides.sides.

Touching the Touching the screen breaks screen breaks

beams that beams that identify the identify the

specific X and Y specific X and Y coordinates.coordinates.

AcousticAcousticFour ultrasonic Four ultrasonic

devices are devices are placed around placed around

the display.the display.When the screen When the screen

is touched, an is touched, an acoustic pattern acoustic pattern is produced and is produced and compared to the compared to the

patterns patterns corresponding corresponding to each screen to each screen

position.position.

Parallel ProcessingParallel Processing



Traditional computers have a single processor. They Traditional computers have a single processor. They execute one instruction at a time and can deal with only one execute one instruction at a time and can deal with only one piece of data at a time. These machines are said to have piece of data at a time. These machines are said to have SISD (Single Instruction, Single Data) architectures.SISD (Single Instruction, Single Data) architectures.

When multiple processors are applied within a single When multiple processors are applied within a single computer, computer, parallel processingparallel processing can take place. There are can take place. There are two basic approaches used in these “supercomputers”:two basic approaches used in these “supercomputers”:

SIMD (Single Instruction, SIMD (Single Instruction, Multiple Data) Multiple Data) ArchitecturesArchitectures

• Each processor does the same Each processor does the same thing at the same time to its thing at the same time to its own portion of the dataown portion of the data

• Example: Have the processors Example: Have the processors perform the graphics rendering perform the graphics rendering for different sectors of the for different sectors of the viewscreen:viewscreen:

MIMD (Multiple MIMD (Multiple Instruction, Multiple Instruction, Multiple Data) ArchitecturesData) Architectures

• At any given moment, each At any given moment, each processor does its own task to processor does its own task to its own portion of the dataits own portion of the data

• Example: Have some processors Example: Have some processors retrieve data, some perform retrieve data, some perform calculations, and some render calculations, and some render the resulting images:the resulting images:

Chapter 5: Computing Components Chapter 5 Computing Components Page 37 In the 1940s and 1950s, John...

Documents

Transcript of Chapter 5: Computing Components Chapter 5 Computing Components Page 37 In the 1940s and 1950s, John...