CSC1100 - Chapter02 - Components of the System Unit

Chapter 2The Components of the

System Unit

Chapter Objectives

Identify chips, adapter cards, and other components in system unit

Identify chips, adapter cards, and other components in system unit

Describe the components of a processorand how they complete a machine cycle

Describe the components of a processorand how they complete a machine cycle

Identify characteristics of various personal Identify characteristics of various personal

Describe the types of expansion slotsand adapter cards

Describe the types of expansion slotsand adapter cards

Explain the differences among a serial port, a parallel port, a USB port, a FireWire port, and other ports

Explain the differences among a serial port, a parallel port, a USB port, a FireWire port, and other portsIdentify characteristics of various personal

computer processors on the market todayIdentify characteristics of various personal computer processors on the market today

Define a bit and describe how a series of bitsrepresents data

Define a bit and describe how a series of bitsrepresents data

Differentiate among the varioustypes of memory

Differentiate among the varioustypes of memory

Describe how busescontribute to acomputer’s processing speed

Describe how busescontribute to acomputer’s processing speed

Identify components in mobile computersand mobile devices

Identify components in mobile computersand mobile devices

The System Unit

What is the system unit?� Case that contains

electronic components of the computer used to process data� Also known as � Also known as

chassis

Learning Outcome

Successful students will be able to:

Describe the characteristics of computer hardware devices and explain their functionalities.

The System Unit

What are common components inside the system unit?

� Memory� Adapter cards

� Sound card

power supply drive bays

processor

� Processor

� Sound card� Video card

� Ports� Drive bays� Power supply

ports memory

sound cardvideo card

The System Unit

What is the motherboard?� Main circuit

board in system unit

� Contains adapter cards, processor cards, processor chips, andmemory chips

� Also calledsystem board

The System Unit

What is a chip?� Small piece of semi-conducting material on which

integrated circuits are etched� Integrated circuits contain many microscopic pathways

capable of carrying electrical current – can contain millions of elements: resistors, capacitors, transistors,…

p. 186

millions of elements: resistors, capacitors, transistors,…

� Chips are packaged so they can be attached to a circuit board

ProcessorProcessor

Control Control UnitUnit

Arithmetic Arithmetic Logic Unit (ALU)Logic Unit (ALU)

Arithmetic Arithmetic Logic Unit (ALU)Logic Unit (ALU)

Processor

What is the central processing unit (CPU)?

� Interprets and carries out basic instructions that operate a computer

InstructionsInstructionsDataData

InformationInformation

Control Control UnitUnit

� Control unit directs and coordinates operations in computer

p. 187 Fig. 4-4

InputInputDevicesDevices

StorageStorageDevicesDevices

OutputOutputDevicesDevicesMemoryMemoryDataData InformationInformation

InstructionsInstructionsDataData

InformationInformation

InformationInformationcomputer

� Arithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations

� Also called theprocessor

Processor

What is a machine cycle?

Step 1. FetchObtain program instruction or data item from memory

� Four operations of the CPU comprise a machine cycle

Processor

Control Unit

Memory

ALU

Step 2. DecodeTranslate instruction into commands

Step 4. StoreWrite result to memory

Step 3. ExecuteCarry out command

Processor

What is pipelining?� CPU begins fetching second instruction before

completing machine cycle for first instruction� Results in faster processing

Stores location Stores location from where instruction from where instruction

Processor

What is a register?� Temporary high-speed storage area that holds

data and instructions

from where instruction from where instruction was fetchedwas fetched

Stores Stores instruction while it is instruction while it is

being decodedbeing decoded

Stores data Stores data while ALU while ALU computes itcomputes it

Stores results Stores results of calculationof calculation

Processor

What is the system clock?� Controls timing of all computer operations� Generates regular electronic pulses, or ticks, that set

operating pace of components of system unit

Each tick Each tick is a is a

clock cycleclock cycle

Pace of system Pace of system clock is clock is clock speedclock speed

Most clock speeds are Most clock speeds are in the gigahertz (GHz) in the gigahertz (GHz)

range (1 GHz = one range (1 GHz = one billion ticks of system billion ticks of system

clock per second)clock per second)

Processor speed can Processor speed can also be measured in also be measured in

mmillions of illions of iinstructions nstructions pper er ssecond econd (MIPS)(MIPS)

Processor

Comparison of some of the more widely used processors

Quick Quiz

1) What is the system unit?Answer: A case that contains electronic components of the computer used to process data

Answer: Many microscopic pathways capable of carrying electrical

2) What does an integrated circuit contain?

Many microscopic pathways capable of carrying electrical current

Answer: The control unit is the component of the processor that directs and coordinates most computer operations; the arithmetic logic unit is the component that performs arithmetic and comparison operations.

3) How is the control unit different from the arithmetic logic unit?

Processor

What are heat sinks, heat pipes, and liquid cooling?

� Heat sink —small ceramic or metal component with fins – absorbs & disperses heat produced by electrical components

� Heat pipe —smaller

Besides computer’s main fan, today’s processors require additional cooling

� Heat pipe e—smaller device for notebook computers

� Liquid cooling —uses a continuous flow of fluids (water, glycol,..) to transfer heat away from processor to a radiator type grill and returns the cooled fluid to the processor

Processor

� Mobile computers & devices often have Low Voltage or Ultra Low Voltage (UVL) processors� Have such low power demands that they do not

require additional cooling.

Processor

What is parallel processing?

Control ProcessorControl Processor

Processor 1Processor 1 Processor 2Processor 2 Processor 3Processor 3 Processor 4Processor 4

� Using multiple processors simultaneouslyto execute a program faster MemoryMemory MemoryMemory MemoryMemory MemoryMemoryfaster

� Requires special software to divide problem and bring results together

Parallel Processing

� Single problem divided into portions

� Multiple processors work on their assigned portions of the problem at the same time

� Some PC use dual-core or multi-core processors

� Others have two or more separate processors � Others have two or more separate processors chips.

� Massively parallel processing� large scale parallel processing � involves hundreds or thousands of processors.� Used by supercomputers – AI & weather forecasting

applications.

Data Representation

How do computers represent data?

� Recognize only two discrete states: on or off

� Use a binary systemto

� Most computers aredigital

� Use a binary systemto recognize two states

� Use Number system with two unique digits: 0 and 1, called bits (short for binary digits)

Data Representation

� Computers – electronic devices powered by electricity – has only two states: ON and OFF

� The digit 0 represents the electronic state OFF:� absence of electronic charge

� The digit 1 represents the electronic state ON: presence of electronic charge

The digit 1 represents the electronic state ON: � presence of electronic charge

� The binary system is a number system that has just two unique digits, 0 and 1, called bit.

� A bit (is not very informative) is the smallest unit of data the computer can process.

Data Representation

What is a byte?� EIGHT bits grouped together as a unit� Provides enough different combinations of 0s and 1s

to represent 256 individual characters� Numbers

� Uppercase � Uppercase and lowercase letters

� Punctuation marks

� Other

Data Representation

What are three popular coding systems to represent data?

� ASCII - American Standard Code for Information Interchange- Used in PCs & servers

� EBCDIC - Extended Binary Coded Decimal Interchange Code- Used primarily on mainframe & supercomputers

(both coding schemes sufficient for English & Western Europe languages but not for Asian, using different alphabets)

� Unicode - 16-bit coding scheme capable of representing allworld’s languages

- implemented in Windows Vista, XP, Mac OS & Linux

ASCII Symbol EBCDIC

00110000 0 11110000

00110001 1 11110001

00110010 2 11110010

00110011 3 11110011

Data Representation

How is a letter converted to binary form and back?

Step 1.The user presses the capital letter D(shift+D key) on the keyboard.

Step 2.An electronic signal for the capital letter D is sent to the system unit.

Step 3.The signal for the capital letter D is converted to its ASCII binary code(01000100) and is stored in memory for processing.

Step 4.After processing, the binary code for the capital letter D is converted to an image, and displayed on the output device.

Quick Quiz

1) What is a dual-core processor? Answer: A single chip that contains two separate processors

2) How are analog signals different from digital signals? Answer: Analog uses continuous (wave form) signals that vary in strength and quality; digital signals, which are used by most computers, recognize only two discrete states: on and off

signals?

Memory

What is memory?� Electronic components that store:

- instructions waiting to be executed,

- data needed by those instructions, and

- the resultsof processed data (information)

� Consists of one or more chips on motherboard or other circuit board

� Each bytestored in memory at unique locationcalled an address

Memory

What is memory? (cont.)

� A byte (a character)– 8 bits - is the basic storage unit in memory

� Each byteresides temporarily in a location in memorythat has an address– a unique number that identifies the location of a byte in memorylocation of a byte in memory

� To access data or instruction in memory, computer references the addresses that contain bytes of data

Memory

How is memory measured?

Term Abbreviation Approximate Size

Kilobyte KB or K 1 thousand bytes

� By number of bytesavailable for storage

Kilobyte KB or K 1 thousand bytes

Megabyte MB 1 million bytes

Gigabyte GB 1 billion bytes

Terabyte TB 1 trillion bytes

� Actually a kilobyte = 1,024 bytes

Memory

What is random access memory (RAM)?

Also called Also called Most RAM is Most RAM is

Memory chips that can be Memory chips that can be read from and written read from and written

to by processor & other devicesto by processor & other devices

The more RAM a The more RAM a computer has, the computer has, the faster it respondsfaster it responds

Also called Also called main memory main memory

or primary or primary storagestorage

volatilevolatile, it is lost , it is lost when computer’s when computer’s

power is power is turned offturned off

Memory

How do program instructions transfer in and out of RAM?Step 1. When you start the computer, certain operating system files are loaded into RAM from the hard disk. The operating system displays the user interface on the screen.

Operating system Operating system instructionsinstructions

Web browser Web browser instructionsinstructions

Operating system Operating system interfaceinterface

Web browser Web browser windowwindow

RAM

Step 2. When you start a Web browser, the program’s instructions are loaded into RAM from the hard disk. The Web browser window is displayed on the screen.

Word processing Word processing program instructionsprogram instructions

Word processing Word processing program windowprogram window

RAM

Web browser program Web browser program instructions are instructions are

removed from RAMremoved from RAM

Web browser Web browser window is no longer window is no longer

displayed on displayed on desktopdesktop

window is displayed on the screen.

Step 3. When you start a word processing program, the program’s instructions are loaded into RAM from the hard disk. The word processing program, along with the Web Browser and certain operating system instructions are in RAM. The word processing program window is displayed on the screen.

Step 4. When you quit a program, such as the Web browser, its program instructions are removed from RAM. The Web browser is no longer displayed on the screen.

Do not have toDo not have tobe rebe re--energizedenergized

as often asas often asDRAMDRAM

Most Most common common

typetype

Memory

What are two basic types of RAM chips?

Static Static

Must be Must be rere--energized energized

constantlyconstantly

Faster and Faster and more reliable more reliable than DRAM than DRAM

chipschips

RAM RAM (SRAM)(SRAM)

Dynamic Dynamic RAM RAM (DRAM)(DRAM)

Newer Type: Magnetoresistive RAM (MRAM)

1 Gb SDRAM Dual-in-line Memory Module

Two types of DIMMs : a 168-pin SDRAM module (top) and a 184-pin DDR SDRAMmodule (bottom).

30- (top) and 72-pin (bottom) SIMMs . Early 30-pin modules commonly had either 256 KB or 1 MB of memory.

http://www.maplin.co.uk/images/Full/a23aj.jpg

http://www.makeitsimple.com/articles/ramguide/ramguidep2.htm

Memory

Where does memory reside?� Resides on small circuit

board calledmemory module

� Memory slotson motherboard hold memory

dual inline memory module

motherboard hold memory modules memory chip memory slot

Memory

How much RAM does an application require?� Depends on the types of

software you plan to use

� For optimal performance, you performance, you need more than minimum specifications

Memory

How much RAM do you need?� Depends on type of applications you intend to run

on your computerRAM

Use

256 MB to 1 GB 512 MB to 1 GB 2 GB and up

• Home and business

users managing

• Users requiring more advanced

multimedia capabilities

• Power users creating

professional Web sites

personal finance

• Using standard

application software

such as word processing

• Using educational

or entertainment

CD-ROMs

• Communicating with

others on the Web

• Running number-intensive

accounting, financial, or

spreadsheet programs

• Using voice recognition

• Working with videos, music, and

digital imaging

• Creating Web sites

• Participating in video conferences

• Playing Internet games

• Running sophisticated

CAD, 3D design, or

other graphics-intensive

software

Memory

What is cache?

� L1 cache built into processor

� L2 cache slower but has larger

� Helps speed computer processes by storing frequently used instructions and data

� Also calledmemory cache

� L2 cache slower but has larger capacity

� L2 advanced transfer cache is faster, built directly on processor chip

� L3 cache is separate from processor chip on motherboard (L3 is only on computers that use L2 advanced transfer cache)

Memory Cache

� Cache speeds up processing time

� It stores frequently used instruction & data.

� When the processors needs them, it searches the memory in an order with greater delay in processing for each level of memory it must searchas the following order:as the following order:� L1 cache, then� L2 cache, then� L3 cache if it exists, then� RAM

� If the instruction or data is not found in memory, then it must search a slower speed storage medium(h/disk, CD, or DVD)

Memory

What is read-only memory (ROM)?

Memory chips that store Memory chips that store permanent data permanent data and instructionsand instructions

Nonvolatile memoryNonvolatile memory, it is not , it is not lost when computer’s lost when computer’s

power is turned offpower is turned off

Three types:Three types:EEPROMEEPROM

((eelectrically lectrically eerasable rasable pprogrammable rogrammable

FirmwareFirmware——ROM chips manufactured ROM chips manufactured with permanently written with permanently written data, instructions, data, instructions, or informationor information

eerasable rasable pprogrammable rogrammable rr eadead--oonly nly mmemory)emory)——

Type of PROM Type of PROM containing microcode containing microcode

programmer programmer can erasecan erase

PROMPROM((pprogrammable rogrammable

rr eadead--oonly nly mmemory)emory)——

Blank ROM Blank ROM chip onto which chip onto which a programmer a programmer

can write permanentlycan write permanentlyUse Microcode instructions to program a PROM chip

Erase microcode with anelectrical signal

Memory

What is flash memory?� Nonvolatile memory that can be erased electronically and rewritten

� Used with PDAs, digital cameras, smart phones, music players, digital voice recorders, printers, Internet receivers, and pagers

flash memory flash memory chips

USB port

from the computer

Portable media player

earphones cable

Memory

What is CMOS?

Complementary metal-oxide

semiconductor memory

Used in some RAM chips, flash

memory chips, and other types of memory chips

Uses battery power to retain

information when other power is

turned off

Stores date, time, and

computer’s startup

information

memory chips

The flash memory chips that store

computer’s startup information

often use CMOS technology

Memory

What is access time?� Amount of time it takes processor

to read data from memory� Measured in nanoseconds(ns),

one billionth of a second� It takes 1/10 of a second to blink

10 million operations = 1 blink

� It takes 1/10 of a second to blink your eye; a computer can perform up to 10 million operations in same amount of time

Term Speed

Millisecond One-thousandth of a second

Microsecond One-millionth of a second

Nanosecond One-billionth of a second

Picosecond One-trillionth of a second

Memory Access Time

� The access time (speed) of memory contributes to the overall performance of the computer.

� Accessing data in memory – 200,000 times faster than h/disk, because of h/disk’s mechanical motion.

� Access time also stated in MHz667 MHz DDR2 SDRAM� 667 MHz DDR2 SDRAM

� Divide 1 billion ns by the megahertz number� 667 MHz = (1,000,000,000/667,000,000)ns ≈ 1.5ns

� Manufacturers & retailers list a computer’s memory in terms of its size, not its access time.� 512 MB of SDRAM upgradeable to 4 GB

Expansion Slots and Adapter Cards

What is an adapter card?� A circuit board that

enhances system unit or provides connections to external devices calledperipherals – devices peripherals – devices connected to system unit & controlled by processor: modems, disk drives, printers, scanners, keyboards,…

� Also called anexpansion card


What is an expansion slot?� An opening, or socket,

on the motherboard that can hold an adapter card

� With Plug and Play, � With Plug and Play, the computer automatically configures cardsand other devices as you install them



What are PC cards, and flash memory cards?

PC card� thin removable flash memory device to

enable wireless Internet access to notebook computers

ExpressCard moduleExpressCard module� Next generation of PC Cards.� Removable flash memory device, to add

memory, storage, sound, fax/modem, communications, and other capabilities to computers


What are PC cards, and flash memory cards?

Flash memory card� allows users to transfer data from

mobile devices to desktop computers� storage capacity range: 32 MB – 8 GB� hot plugging – feature allows user to � hot plugging – feature allows user to

insert & remove the removable flash memory & other devices while computer is running

USB Flash drive � flash memory storage that plugs in a

USB port on a computer� 32 MB – 64 GB

Ports and Connectors

What are ports and connectors?� Port connects external devices to system unit� Connector joins cable to peripheral

� Male connector: have 1 or more pins

� Female connector: have matching hollows to accept the pins on a male connector


What are different types of connectors?


What is a serial port?� Transmits one bit of data at a

time� Connects slow-speed devices,

such as mouse, keyboard, modemmodem

� E.g. COM port


What is a parallel port?� Connects devices that can

transfer more than one bit at a time, such as a printer

� Can transfer 8 bits of data (one byte) simultaneously (one byte) simultaneously through 8 separate lines in a single cable


What are USB ports?

USB (universal serial bus) port can connect up to 127 different peripherals together

with a single connector type

USB (universal serial bus) port can connect up to 127 different peripherals together

with a single connector type

Third USB device connects to second USB

device, and so on

Third USB device connects to second USB

device, and so on

Second USB device connects

to first USB device

Second USB device connects

to first USB deviceFirst USB

device connects to USB port on computer

First USB device connects

to USB port on computer

Single USB port can be used to attach

multiple peripherals in a daisy chain

Single USB port can be used to attach

multiple peripherals in a daisy chain

PCs typically have six to eight USB ports

on front or back of the system unit

PCs typically have six to eight USB ports

on front or back of the system unit


What are FireWire ports?

� Similar to a USB port� Connects multiple types of devices that require

faster data transmission speeds: digital video camera, color printer, scanners, digital cameras, camera, color printer, scanners, digital cameras, DVD drives,…

� Allows you to connect up to 63 devices together� Can use FireWire hub to attach multiple devices

to a single FireWire port


What are special-purpose ports?

� MIDI (Musical Instrument Digital Interface) port

� eSata(external SATA – Serial Advances Technology Attachment) port– connect SATA h/disk to computer

� Not included in typical computer� Allow users to attach specialized peripherals or transmit data

to wireless devices

Attachment) port– connect SATA h/disk to computer

� SCSI(small computer system interface) port

� IrDA (Infrared Data Association) port– data transmission via infrared light waves; need to align the IrDA port on the device with IrDA port on the computer (like television remote control)

� Bluetooth port – Bluetooth technology uses radio waves to transmit data between two devices; do not need to be aligned with each other)



USB & FireWire ports are replacing traditional ports completely

Buses

What is a bus?� Channel that allows devices

inside computer to communicate with each other

� Data bus– transfers actual data� Address bus– transfers the info. where

the data should reside in memorythe data should reside in memory� System bus connects processor and RAM� Bus width determines number of bits

transmitted at one time (32-bit, 64-bit bus)� Word size is the number of bits processor

can interpret and execute at a given time; in most computers, the word size is the same as the bus width

� Bus clock speed: 1066 MHz

Memory chips

Buses

System Bus/Front Side Bus (FSB)� Part of motherboard� Connects processor to main memory

Expansion Bus� Allows processor to communicate with peripherals

PCI bus (Peripheral Component Interconnect bus)� PCI bus (Peripheral Component Interconnect bus)� PCI Express bus� Accelerated Graphics Port (AGP) bus� USB & FireWire bus� PC Card bus

FireWireBus

PCIBus

AGPBus

USBBus

Bays

What is a bay?� Open area inside system

unit used to install additional equipment

� Drive baystypically hold disk drivesdisk drives

� External drive bay – allow user to access the drive from outside the system unit: CD & DVD drives

� Internal drive bay – within system unit: h/disk

Power Supply

What is a power supply?

ConvertsAC Power

into

Fan keepssystem unit components

External peripherals might use an AC

adapter, which is an external power supply

DC Power cool

One end of AC adapter plugs in the wall outlet & the other end attached to the peripheral.

The AC adapter converts the AC power into DC power that the peripheral requires.

Mobile Computers and Devices

What is a mobile computer?� Notebook, weighing between 2.5 and 8 pounds, or

mobile device such as a PDA


What ports are on a notebook computer?


What ports and slots are on a tablet PC?

Putting It All Together

What are suggested processor, clock speed, and RAM requirements based on the needs of various types of users?

Keeping Your Computer Clean

Over time, the system unit collects dust – even in a clean environment

� Preventative maintenance requires a few basic products: