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Chapte

r

1 Introduction to

a Typical PC

Chapter

Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website.

Objectives

• Give examples of how computers are used.

• Contrast analog and digital electronics.

• Give examples of computer data.

• Interpret binary and hexadecimal numbers 0

through 15.

• Compare bit, byte, and word.

• Contrast serial and parallel data transfer.

• Interpret the common prefixes associated with

the computer’s size and speed.

• Identify external computer connections.


Objectives (Continued)

• Identify the major components of a typical PC.

• Explain how the major computer components

interact with each other.

• Contrast electrostatic discharge,

electromagnetic interference, and radio

frequency interference.

• Identify common PC service tools.

• Recall common safety practices related to

computer repair.


Key Terms

• A+ Certification

• American Standard Code for Information Interchange (ASCII)

• analog electronics

• anti-static wrist strap

• battery

• binary number system

• Bit

• byte

• central processing unit (CPU)

• CompTIA

• computer

• cooling fan

• data

• device bay

• digital electronics


Key Terms (Continued)

• driver

• electromagnetic interference (EMI)

• electrostatic discharge (ESD)

• expansion card • expansion card slot

• external SATA

• firmware

• hard drive

• hexadecimal number system

• hot swap

• integrated circuit (IC)

• motherboard

• parallel transfer

• peripheral

• power eSATA (eSATAp)

• power supply


Key Terms (Continued)

• radio frequency interference (RFI)

• random access memory (RAM)

• serial transfer

• word


Introduction to a Typical PC

• A+ Certification awarded after successful

completion of the CompTIA A+ exams

– A+ Certification recognized throughout the industry

– A+ Certification covers basic PC repair and support

skills

– CompTIA is a not-for-profit, vendor-neutral

organization that certifies the competency level of

technicians


The Role of Computers

• Computers are part of every aspect of our lives.

• The make up of a computer can seem

intimidating, but the mechanics are simple.

• This textbook teaches skills to be successful in

computer technology.


Digital Electronics

• All electronic components fall into one of two

categories: digital electronics and analog

electronics.

– Digital electronics is an electronic system

represented by a simple switch, which is either on

or off.

– Analog electronics is an electronic system that

uses and produces varying voltage levels.


Digital Electronics (Continued)

Goodheart-Willcox Publisher

Digital System

Analog System



Describe the difference between a digital and

an analog electronic device.

Digital devices accept discrete levels of input

and produce discrete levels of output. Analog

devices accept continuous ranges of input to

produce continuous ranges of input to produce

continuous ranges of output.

Review


What Is a Computer?

• A computer is an assembly of electronic modules

that interact with computer programs known as

software to create, modify, transmit, store, and

display data.

– Computers have rapidly evolved from simple

electronic devices to highly sophisticated pieces of

technology.

– Computers appear to be intelligent but really only

process and store data.


What Is a Computer? (Continued)

• Data is information that is stored and processed

by computers.

– Data inside the computer is represented

electronically as high and low voltages, which

create a digital signal.

– Data in a computer system is represented as ones

and zeroes, a pattern known as the binary system.


Computer Data Codes

• Data can be numbers, text, pictures, or sound.

• Data can be expressed in different forms.

– Voltage levels

– Numeric systems

• Binary

• Hexadecimal

– Symbolic codes, such as ASCII

• Data should be expressed in the way that is

easiest to grasp for the given material.


Computer Data Codes (Continued)

• The binary number system consists of entirely

ones and zeroes.

– Digital devices have two states (off and on), which

are reflected in two numbers (0 and 1).

– One and zeros of this system are used to represent

high and low voltage signals.



Binary Number System



• The hexadecimal number system is a computer

code system that uses 16 characters.

– The system uses a combination of numerals 0

through 9 and the letters A through F.

– It best matches the hardware systems of

computers.

– The system can be used in combination with the

binary system.



Hexadecimal Number System



• American Standard Code for Information

Interchange (ASCII) is a symbolic code in which

data can be expressed.

– It was the first attempt to standardize computer

character codes among the varieties of hardware

and software.

– It had limitations, such as not allowing for

variations in fonts, a common requirement of word-

processing software.


Bits, Bytes, and Words

• Bit, byte, and word are basic computer units of

data based on the binary number system.

– Bit, short for binary digit, is a single binary unit of

one or zero.

– A byte is equal to eight bits.

– A word is the total amount of bytes a computer can

process at one time.


Bits, Bytes, and Words (Continued)

Unit Definition Example

Bit 0 or 1 1

Byte eight bits 01011110

Word 1 to 8 bytes 10010010 11110000 00110011

10101010


Serial and Parallel Data Transfer

• Data is transferred in one of two modes in a

computer system: series or parallel.

• Ports in a computer are classified as serial or

parallel.

– In a serial transfer, data is sent through a port one

bit at a time in successive order.

– In parallel transfer, more than one bit is sent side

by side, eight bits at a time.


Serial and Parallel Data Transfer (Continued)

Serial and Parallel Data Transfer



Computer Numerical Values

• Metric prefixes are used to express the speed and

size of computer systems and hardware.

• Prefixes are used in combination with the word bit

(b) or byte (B).

– Speed is usually expressed in bits.

– Storage is usually expressed as bytes.


Computer Numerical Values (Continued)

Metric Prefix Chart


Computer Numerical Values (Continued)

Comparison between Base 2 and Base 10 Number Systems


The binary system consists of the decimal

numbers ____ and ____.

0,1

There are eight ____ in one____.

bits, byte

Describe the difference between serial data

transfer and parallel data transfer.

In a serial transfer, data is sent through a port

one bit at a time in successive order; in parallel

transfer, more than one bit is sent side by side.

Review


Take a Tour Outside the Computer Case

• A minimal workstation consists of a computer and

input and output devices.

– The computer is a case that houses the

motherboard, CPU, memory, and hard drive.

– Typical input devices include the keyboard and

mouse.

– Typical output devices are the monitor, printer, and

speakers.


Take a Tour Outside the Computer Case (Continued)

• Peripherals are optional pieces of equipment used

to display data or to input data.

– Monitor displays data as words or pictures.

– Printer displays data in printed form.

– Speakers convert data into sound.

– Keyboard is used to enter data.

– Mouse is used to interact with coordinates on the

display.

– Touch screen can be both input and output.



• There are many different case styles used to

contain and protect the electronic part of a

computer.

• Most common case styles

– Desktop

– Tower

– Mini tower

– Micro tower

– Laptop

– Notebook



• Exterior of the computer allows access to the

electronic parts inside.

• Data can be entered through the hard drive,

optical drive, keyboard, mouse, or one of the ports

in the back.



• Mini-DIN is an exterior connection used for the

mouse and the keyboard that may not be

interchangeable.

• FireWire is an exterior connection also known as

the IEEE-1394 connector.

– Made to allow hot swaps, meaning a device

can be plugged in or unplugged while the PC is

running

– Made for very high-speed data transfers



• Universal Serial Bus (USB) is a multipurpose

exterior connection that allows many different

devices to connect to a PC.

– Connects up to 127 devices in a daisy-chain

fashion

– Eliminates the need to open the PC case to

connect some peripherals



• A device bay is a drive bay designed to

accommodate the easy hot swap of devices such

as hard drives, tape drives, and optical drives.

– Prewired for either USB or FireWire

– Eliminates the problem of running long cords

across work surfaces



• There are two types of RJ connectors commonly

used: RJ-11 and RJ-45.

– RJ-11 for telephone connections

– RJ-45 for network connections

• DB connector looks similar in shape to the letter

D.

– Options include a 9-, 15-, or 25-pin

– Current computers have no DB connections,

replaced by USB



• VGA, DVI, and HDMI are used as monitor

connections.

– VGA is used for analog connections.

– DVI and HDMI are used for digital connections.

• External SATA devices require two connections.

– External SATA port provides a data connection to

an external SATA device.

– Power eSATA port, also called the eSATAp,

provides data connection and electrical power.



Typical Exterior Connections



Take a Tour Inside the Computer Case

• The inside of a PC has several standard components.

– Central processing unit (CPU)

– Power supply

– Hard drive

– Motherboard

– RAM

– Firmware

– Battery

– Expansion cards

– Expansion card slots

– Cooling fan

– Cables


Take a Tour Inside the Computer Case (Continued)

• The central processing unit (CPU) is the brain

of the computer.

– Intel® Core® i7, Intel® Pentium® , Intel® Celeron®,

AMD FV 8-Core, and AMD Phenom™ are various

models of CPUs.

– All other components depend on the CPU.

– CPU controls the data in the computer.

– The CPU translates commands into actions.

– CPU carries out the program codes written in the

software program.



AMD Athlon™ 64 FX-70 series processor. Courtesy of Advanced Micro

Devices, Inc.

One CPU Model



• The power supply converts the 120-volt ac

power from the wall outlet to dc voltage levels

used by the various computer components.

• The hard drive is where computer programs and

data are stored.

– The hard drive is also called the internal hard drive

or hard disk drive.

– Programs and data are stored as magnetic

patterns on the hard drive.



Goodheart-Willcox Publisher Goodheart-Willcox Publisher

Hard Drive Power Supply



• The motherboard is usually a rectangular piece

of circuit board covered with many conductors

that provide electrical energy paths to the

computer components and expansion slots.

– The motherboard provides a way to distribute the

digital signals.

– The motherboard is an electrical system of

pathways referred to as the computer bus.




Motherboard



• Random access memory (RAM) is where

computer programs are loaded to and from the

hard drive.

– RAM is classified as volatile memory, meaning that

data is lost when the power is turned off.

– The amount of RAM required to run applications

will vary.

– RAM is where data is temporarily stored.

– RAM is emptied when a computer is turned off.




Three Difference Types of RAM Modules



• Firmware is hardware-specific software required

to boot the computer and support communication

between the operating system and hardware

devices.

– Interprets commands of higher-level software

programs, such as operating systems.

– Translates the commands into actions hardware

devices, such as the hard drive, can understand.



• Firmware and drivers work hand in hand.

– A driver is a small software program written

specifically for a hardware device.

– Drivers allow operating system to properly

communicate with a device.

– Without the driver, the device will not function

properly.



• CMOS, and BIOS are distinctly different from

firmware.

– CMOS is where the Setup utility stores information

about the computer’s hardware, date, and time.

– BIOS is a type of firmware written in machine

language.

• Machine language uses hexadecimal codes to write

a program.

• Because there is no single BIOS standard, BIOS

systems are diverse.

• BIOS soon will be replaced by UEFI.



• The battery supplies voltage to the CMOS, which

contains the firmware setup data.

– Without the battery, the computer would lose the

date, time, and all important information about the

hardware components when the power switch is

turn off.

– The battery allows information to be saved while

the PC is powered down.




Computer Battery



• An expansion card is a board that can be easily

installed in a computer to enhance or expand its

capabilities.

– An expansion card is also called an interface card

or host adapter.

– This component is used for such devices as TV

tuners, video cards, sound cards, and modems.

– Many devices designed to be added to expansion

cards have been redesigned as exterior devices

that connect typically through a USB port.




Expansion Card



• An expansion card slot is a receptacle for an

expansion card, which allows the card to connect

to the motherboard’s circuitry.

• The cooling fan supplies a constant stream of air

across the computer components.

• Cables, such as the SATA and the PATA, connect

the motherboard to devices such as the hard drive

and optical drive.




SATA and PATA Cables


Expansion Card Slots


How the Major Parts Work Together

1. Power switch is turned on and electrical power

goes from the wall outlet into the computer

system.

2. Firmware system is activated and performs a

power-on self-test (POST), checking the RAM,

ROM, hard drive, and keyboard.

3. Operating system takes control of the system.

4. CPU waits for activity to be generated by the

mouse, keyboard, modem, or other input device.


How the Major Parts Work Together (Continued)

5. Mouse pointer is moved to an icon and the mouse is clicked to activate a program, such as a word-processing program.

6. Some typing is done, and the save command is issued by clicking the save icon. The operating system takes over to interpret the command.

7. The firmware translates the instructions from the operating system to the storage media, activating the hard drive motor and actuator arm.

8. Control is returned to the program, so long as an error had not occurred.


Integrated Circuits

• The term chip is often used in the computer

industry and is the final product of the

manufacturing of an integrated circuit.

• An integrated circuit (IC) is a collection of

transistors, resistors, and other electronic

components reduced to an unbelievable small

size.

• Over six million transistors manufactured as an

integrated circuit can fit into an area the size of a

dime.


Integrated Circuits (Continued)

• Manufacturing an integrated circuit takes many

hundreds of steps.

– The circuit is drawn on a very large scale and

drawings are photographed.

– The negative of the photograph is used as a

template.

– An ingot of pure silicon is made and sliced into thin

wafers to serve as the base.

– A series of layers are produced over the silicon

wafer using a process called photolithography.




Manufacture of Integrated Circuits



• A coating of a chemical called photoresist is laid

over the entire surface of the wafer, which will

react when exposed to UV light.

• Ultraviolet light is shone through the negative,

causing the photoresist to leave a pattern of soft

and hard surfaces in the exact pattern of the

designed circuit.



• The soft photoresist is washed away, leaving an

etched pattern of valleys and ridges on the

surface of the wafer.

• The valleys are filled in with conductive material,

called doping or implantation.

• The process is repeated multiple times until 20 or

more layers are developed over the entire wafer.

• Single wafer is cut into several individual circuits.



• Electrostatic discharge (ESD) is best defined in

the world of computer maintenance as the

transfer of static electrical energy from one object

to another.

– An ESD will damage the circuits of a microchip.

– Technicians wear an anti-static wrist strap, which

connects the technician to ground and bleeds off

any electrostatic charge.

– Electronic parts and devices are shipped inside

anti-static bags to prevent ESD.



Anti-Static Kit




• Electromagnetic Interference (EMI) is

interference or damage to components caused by

magnets and magnetic fields.

– Any device that operates on magnetic principles

should not come in contact or close proximity to a

magnetic field.

– Most common source of a magnetic field is

magnetic tools.

– Some computer chips can be damaged by strong

magnetic force, but most are designed with

magnetic shielding.



• Radio frequency interference (RFI) is

interference produced by electronic devices that

use radio waves.

– Wireless network devices can fail or operate

erratically because of radio frequencies broadcast

by other devices.

– Common devices that generate RFI are cell

phones, cordless phones, wireless network

components, and microwave ovens.


What components are found in a typical computer

workstation?

Some common PC components are CPU, cooling

fan, motherboard, RAM power supply, hard drive,

expansion cards, and cables.

What is the purpose of the battery mounted on the

motherboard?

The battery supplies voltage to the CMOS chip that

contains the firmware setup data.

Describe the difference between ESD, EMI, and RFI.

ESD is a static charge of electricity; EMI is

interference or damage to components caused by

magnets and magnetic fields; and RFI is interference

produced by electronic devices that use radio waves.

Review


Tool Kit

• Computer repair requires a minimum number of

tools and can vary.

– A variety of screwdrivers are needed, a chip

puller, anti-static wrist strap, multimeter, extra

screws, and an extraction device are helpful.

– Canned compressed air may be necessary.


Tool Kit (Continued)

• A software tool kit is important as well.

– Software will be used to troubleshoot,

diagnose, and repair PCs.

– Many software tools can be found as

shareware, which is software that is freely

distributed, usually via the Internet.


Safety

• Safety is the responsibility of everyone.

• Precautions should be taken to ensure physical

safety.

– Cables, such as power cords or network cables,

should be properly secured to avoid causing a

tripping hazard.

• Tape the cable to the floor

• Use a cable floor runner

– Avoid touching electronic components while the

computer is energized.


Safety (Continued)

• Other steps should be taken to ensure physical

safety of computer technicians and users.

– Loose clothing and inappropriate footwear should

not be worn in the computer repair environment.

– When the weight of an object exceeds 50 pounds,

two or more people should lift it or special

equipment designed for lifting and hauling heavy

objects should be used.


Safety (Continued)

• Electrical hazards in a computer lab should be

understood.

– Do not attempt to open, inspect, or repair any electronic

device that you have not been trained on by your

instructor or if you have nor received your instructor’s

permission.

– Disconnect electrical power before opening any

computer case.

– Remove jewelry before working inside a computer

case.


Safety (Continued)

• The possibility of fire is always a threat in a

computer laboratory.

• The acronym PASS is used to remember the

proper procedure for using a fire extinguisher

P = Pull the pin.

A = Aim at the base of the fire.

S = Squeeze the handles together slowly to discharge the fire extinguisher.

S = Sweep the nozzle from side to side moving carefully toward the fire while keeping the discharge aimed at the base of the fire.


Safety (Continued)

Five Classes of Fire Extinguishers



Safety (Continued)

• Computer technicians come into contact with hazardous materials and thus, need to practice chemical safety.

– A Material Safety Data Sheet (MSDS) is required by federal law for hazardous materials.

– An MSDS includes proper handling, storage, and disposal of the material, and health effects or harmful effects from breathing and contact with skin or eyes.

– The Environmental Protection Agency (EPA) provides information about how to properly dispose of and recycle electronic equipment.


What does the fire protection acronym PASS

represent?

Pull the pin. Aim at the base of the fire.

Squeeze the handles. Sweep the nozzle side to

side at the base of the fire.

What government organization is responsible

for safety education and enforcement in the

work area?

The Occupational Safety and Health

Administration (OSHA) is responsible for safety

education and enforcement in the work area.

Review

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