computer architecture how does a computer work? chapter 6

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Computer Architecture How Does a Computer Work? Chapter 6

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Computer Architecture

How Does a Computer Work?

Chapter 6

©2003 The McGraw-Hill Companies

Student Learning Outcomes

1. Explain the basic components (inside the box) of a personal computer and their related functions.

©2003 The McGraw-Hill Companies

System Unit

• System unit is the case or box in which the motherboard and storage units are housed

p. 6.162 Fig. 6-1

©2003 The McGraw-Hill Companies

6.1 The Big Picture

InputData

InputData Process

Data

Process Data

OutputInformation

OutputInformation

©2003 The McGraw-Hill Companies

The System Unit

• Motherboard is the large circuit board inside your system unit that holds the CPU, memory, and other essential electronic components

• CAN YOU NAME THE PARTS?

p. 6.164 Fig. 6.3

SimNet Concepts Support CD: “The Motherboard” and “Inside the Computer”

©2003 The McGraw-Hill Companies

System Unit Terminology

CPU – Chip that carries out

instructions it receives from the

software

RAM – Temporary memory that holds

software instructions and information for

the CPU

Port – Place through which

information and instructions flow to

your computer system

Connector - plug used to connect a device

to a computer

©2003 The McGraw-Hill Companies

System Unit Terminology

Expansion Card – Circuit board that is

inserted into an expansion slot

Expansion Bus – highway system that moves information coming from

& going to devices outside the motherboard

Expansion Slot – socket on the

motherboard into which an expansion

card is inserted

©2003 The McGraw-Hill Companies

6.2 Representing Information Inside a Computer

• Binary digit (bit) has two states - 0 or 1• By combining bits into groups of 8, we

can represent letters, symbols, and numbers, like the word "cool" (below)

• A group of 8 bits represents one natural language character and is called a byte

01000011 01001111 01001111 01001100

C O O L

©2003 The McGraw-Hill Companies

ASCII, EBCIDIC, and Unicode

• ASCII —American Standard Code for Information Interchange

• Used on personal computers; eight-bit coding system; 256 different patterns

• EBCDIC —Extended Binary Coded Decimal Interchange Code

• Used by IBM mainframes; eight-bit coding system; 256 different patterns

• Unicode —coding scheme capable of representing many languages

• Usable on many computers; 16-bit coding system; approximately 65,000 patterns

SimNet Concepts Support CD: “Data Representation Using Binary Codes”

©2003 The McGraw-Hill Companies

ASCII & EBCDIC Binary Representations

YOUR CHARACTERS ASCII EBCDIC

(space) 00100000 01000000

! 00100001 01011010

# 00100011 01111011

$ 00100100 01011011

& 00100110 01010000

0 00110000 11110000

1 00110001 11110001

2 00110010 11110010

3 00110011 11110011

4 00110100 11110100

5 00110101 11110101

6 00110110 11110110

7 00110111 11110111

8 00111000 11111000

9 00111001 11111001p. 6.168 Fig. 6.7

©2003 The McGraw-Hill Companies

6.3 CPU, RAM, and Machine Cycles

• Central processing unit (CPU or microprocessor or processor). Chip that carries out instructions it receives from your software

• Random access memory (RAM) Temporary memory that holds software instructions and information for the CPU

• Machine cycle (CPU cycle or clock cycle) consists of retrieving, decoding, and executing the instruction, and returning the result to RAM

©2003 The McGraw-Hill Companies

Central Processing Unit

Chip that carries out instructions it receives from your software

Chip that carries out instructions it receives from your software

Role of the CPU is analogous to the role of

your brain – keeps everything functioning

as it’s supposed to

Role of the CPU is analogous to the role of

your brain – keeps everything functioning

as it’s supposed to

p. 6.169 Fig. 6.3

SimNet Concepts Support CD: “The CPU”

©2003 The McGraw-Hill Companies

Application Application

Software Software

instructionsinstructions

Work being Work being

createdcreatedOS InstructionsOS Instructions

Keyboard

Strokes & Mouse

Movements

Random Access Memory (RAM)

RAM Holds RAM Holds

©2003 The McGraw-Hill Companies

Machine Cycle (CPU Cycle)

4. Store the result

In RAM

4. Store the result

In RAM

Machine cycle consists of:

3. Execute the

instruction

3. Execute the

instruction2. Decode the

instruction

2. Decode the

instruction

1. Retrieve an instruction from RAM

©2003 The McGraw-Hill Companies

How a CPU Works

p. 6.170 Fig. 6.9

©2003 The McGraw-Hill Companies

CPU Clock

Each beat or tick of the Each beat or tick of the clock is called a CPUclock is called a CPUcycle/machine cyclecycle/machine cycle CPU speed is quoted in CPU speed is quoted in

Megahertz (MHz = 1 millionMegahertz (MHz = 1 million

CPU cycles per second) or CPU cycles per second) or

Gigahertz (GHz= 1 billiion Gigahertz (GHz= 1 billiion

CPU cycles per second).CPU cycles per second).

©2003 The McGraw-Hill Companies

Classes of CPU’s

• Intel and AMD are two major manufacturers of CPUs for consumer computers

• CPU speed and power continue to get faster

• Higher-performance CPUs have top speeds and are the most expensive

©2003 The McGraw-Hill Companies

RAM Capacity

• “Buy as much as you can afford”. For optimal performance purchase, more than the minimum specifications

• 512 MB is standard on new computers – i.e. 512 million bytes

p.6.173 Fig. 6.13

SimNet Concepts Support CD: “Memory”

©2003 The McGraw-Hill Companies

RAM Capacity: How Much Do You Need?

– Byte– Kilobyte (KB)– Megabytes (MB)– Gigabytes (GB)– Terabytes (TB)– Petabyte (PB)– Exabyte (EB)

= 8 bits≈ 1 Thousand Bytes≈ 1 Million Bytes≈ 1 Billion Bytes≈ 1 Trillion Bytes≈ 1 quadrillion Bytes≈ 1 quintillion Bytes

©2003 The McGraw-Hill Companies

RAM Capacity: How Much Do You Need?

– Byte– Kilobyte (KB)– Megabytes (MB)– Gigabytes (GB)– Terabytes (TB)– Petabyte (PB)– Exabyte (EB)

= 8 bits≈ 1000≈ 1000000≈ 1000000000≈ 1000000000000≈ 1000000000000000≈ 1000000000000000000

©2003 The McGraw-Hill Companies

RAM and Virtual Memory

• If your computer runs out of physical RAM space, it uses hard disk space as temporary RAM, which is called virtual memory

• Virtual memory is slower than physical RAM because instructions temporarily stored on the hard disk must be moved into RAM as they are needed

©2003 The McGraw-Hill Companies

How Virtual RAM Works

p.6.174 Fig. 6.14

©2003 The McGraw-Hill Companies

6.4 Making Connections

p.6.175 Fig. 6.15

• Ports are places in a computer system where external devices are plugged in, and through which information and instructions flow into the computer system

• Connectors consist of cables that are used to join peripheral to the computer. Common types of connectors: • USB• Firewire• Serial• PS/2• Parallel• RJ-45

©2003 The McGraw-Hill Companies

USB Connectors and Ports

• USB (Universal serial bus) connector – is a plug-and-play interface between a computer and add-on device

• With plug and play, a new device can be added to your computer without having to add an adapter card or even having to turn the computer off

©2003 The McGraw-Hill Companies

Firewire (IEEE 1394)

• Firewire (IEEE1394) although different from USB, allows you to connect hot-swap, plug and play devices to your computer

• Firewire used mostly for video camcorders and digital video disk (DVD) players

• A popular implementation of IEEE 1394 is Sony’s I-LINK

©2003 The McGraw-Hill Companies

Serial Connectors and Ports

• Serial means one event at a time. It is usually contrasted with parallel, meaning more than one event happening at a time

• In the context of computer hardware and data transmission, serial connection, operation, and media usually indicate a simpler, slower operation and parallel indicates a faster operation

©2003 The McGraw-Hill Companies

Parallel Connectors and Ports

• On a PC, the printer is usually attached through a parallel interface and cable so that it will print faster

• Keyboard and mouse are one-way devices that only require a serial interface and line

SimNet Concepts Support CD: “Ports and Cables”

©2003 The McGraw-Hill Companies

Wireless Ports

• Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communications path

©2003 The McGraw-Hill Companies

Wireless Ports – Cont.

• Common examples of wireless equipment – Cellular phones– Global positioning systems– Cordless mouse– Wireless networks– Baby monitors– TV remote controls

p.6.178 Fig. 6.17

©2003 The McGraw-Hill Companies

Wireless Ports

• IrDA (Infrared Data Association) port– Use infrared light to

send and receive information

• Bluetooth uses radio waves over distances of up to 30 feet

©2003 The McGraw-Hill Companies

IrDA (Infrared Data Association)

• In this form of radio transmission, a focused ray of light in the infrared frequency spectrum, measured in terahertz, or trillions of hertz (cycles per second), is modulated and sent from a relatively short distance

• IrDa communications is playing an important role in wireless data communication due to the popularity of laptop computers, personal digital assistants, digital cameras, mobile telephones, pagers, and other devices

©2003 The McGraw-Hill Companies

Examples for Using IrDA

• Exchange business cards between handheld PCs

• Send a document from a notebook computer to a printer

• Coordinate schedules and telephone books between a desktop and notebook computer

©2003 The McGraw-Hill Companies

Examples for Using IrDA

• Send faxes from a notebook computer to a distant fax machine through a public telephone

• Beaming images from a digital camera into a computer

• Interconnecting local area networks. Maximum effective distance is somewhat under 1.5 miles

©2003 The McGraw-Hill Companies

Bluetooth

• Bluetooth is a computing and telecommunications industry specification that describes how mobile phones, computers, and PDAs can easily interconnect with each other and with home and business phones and computers using a short-range wireless connection

• Bluetooth requires that a low-cost transceiver chip be included in each device

©2003 The McGraw-Hill Companies

Expansion Slots on the Motherboard

SimNet Concepts Support CD: “Expansion Cards and Slots”

©2003 The McGraw-Hill Companies

Buses

• Data buses– Carries information in the form of bits around

the motherboard– Two types: system and expansion

• System bus – Electrical pathways which move information

between RAM and CPU– The more bits that can travel together at one

time, the faster the bus

©2003 The McGraw-Hill Companies

Expansion Bus

• Moves information coming from and going to devices outside the motherboard

• Types of expansion buses– ISA (industry standard architecture)

– PCI (peripheral component interconnect)

– AGP (accelerated graphics port)

©2003 The McGraw-Hill Companies

PCI and AGP Buses

p.6.180 Fig. 6.19

©2003 The McGraw-Hill Companies

6.5 Notebook Computers

• Notebook computer is smaller and power to run devices is limited

• Biggest advantage is its portability

• Electronic engineers work to reduce the power and size requirements of these computers

©2003 The McGraw-Hill Companies

Notebook Computers CPUs and RAM

• Notebook hardware has special features

• A mobile CPU is a special type of CPU for a notebook computer that changes speed, and therefore power consumption, in response to fluctuations in demand

• The CPU fan comes on only when the CPU gets too hot

• RAM for a notebook looks a little different from desktop RAM

Notebook RAM

Desktop RAM

p. 6.181 Fig. 6.13 & 6.20

©2003 The McGraw-Hill Companies

Notebook Computers – Expansion Cards and Slots

• Devices are added to a notebook by sliding a PC card into the PC Card slot on the notebook, and connecting the device to the PC card

• A PC Card is the expansion card used to add devices to notebook computers

p.6.181 Fig. 6.21

©2003 The McGraw-Hill Companies