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Chapter 1: Introduction to the
Personal Computer
IT Essentials v6.0
ITE PC v4.1
Chapter 1
© 2007 – 2010, Cisco Systems, Inc. All rights reserved.
Cisco Public
1
CompTIA A+ Certification
An A+ Certification candidate must pass two exams:
1. CompTIA A+ 220-901: Focus on Hardware and Troubleshooting
PC Hardware
Networking
Mobile Devices
Hardware and Network Troubleshooting
2. CompTIA A+ 220-902: Focus on Software and Troubleshooting
Windows Operating Systems
Other Operating Systems and Technologies
Security
Software Troubleshooting
Operational Procedures
Personal Computer Systems
Cases and Power Supplies
 Cases

influences the motherboard form factor choice

must support all internal devices

must allow for good air flow

available in different sizes
 Power Supplies
•
provide power to all computer components so
must be chosen based on current and future
needs

convert AC power from the wall socket into DC, which is a lower voltage

deliver different voltage levels to meet different internal component needs

Cables, connectors, and components are designed to fit together snugly--never force
any connector or component.

Connectors are generally “keyed,” which means they fit in only one way.

Some power supplies are proprietary to be used with proprietary connectors required by
some motherboards.
Power Supplies
 On the back of the power supply is a
small switch called the voltage selector switch.
 This switch sets the input voltage to the power supply to either
110V/115V or 220V/230V. The correct voltage setting is determined by the
country where the power supply will be used.
 Setting the voltage switch to the incorrect input voltage could damage the
power supply and other parts of your computer. If a power supply does not
have the voltage selector switch, your power supply will automatically
detect and set the correct voltage.
 If you suspect the power supply is not functioning, you can test it with a
power supply tester.
 A computer can tolerate slight fluctuations in power, but a significant deviation can cause the
power supply to fail. An uninterruptible power supply (UPS) can protect a computer from
problems caused by changes in power. A UPS provides power for a computer using a power
inverter. A power inverter provides AC power to the computer from a built-in battery by
converting the DC current of the UPS battery into AC power.
Ohm’s Law
 There is a basic equation that expresses how three of the terms
relate to each other. It states that voltage is equal to the current
multiplied by the resistance. This is known as Ohm's Law.
• V = IR
 In an electrical system,
power (P) is equal to the
voltage multiplied by the
current.
• P = VI
If wire from the power supply is carrying
120W of power and 24A of current, which
color(s) of cable is the wire?
• V = P/I
Motherboard Form Factors
 The form factor of motherboards pertains to the size
and shape of the board.
 It also describes the physical layout of the different
components and devices on the motherboard.
 Various form factors exist for motherboards.
Motherboards
 the main printed circuit board
 contains the buses or electrical
pathways found in a computer—
buses allow data to travel
among the various components
 also known as the system board,
the backplane, or the main board
 accommodates CPU, RAM,
expansion slots, heat sink/fan
assembly, BIOS chip, chipset,
sockets, internal and external
connectors, various ports, and the
embedded wires that interconnect the
motherboard components
 The amount of memory that can be
installed and type of connectors
that will be on the motherboard are
determined by the chipset.
• The Northbridge (generally closest to the
CPU) controls access to the RAM, video card,
and the speeds at which the CPU can
communicate with them. The video card is
sometimes integrated into the Northbridge.
• The Southbridge, in most cases, allows the
CPU to communicate with the hard drives,
sound card, USB ports, and other I/O ports.
Motherboards
Motherboards
Let’s see what you have learned . . .
Q: Which chip controls access to the RAM, video card,
and the speeds at which the CPU can communicate
with them?
A: Northbridge
Q: What factors that must be considered when choosing
a computer case?
A: internal drive locations, the size of the
motherboard, the size of the power supply
Q: Where can the input voltage selection be changed
from 110 volts to 220 volts on a computer system?
A: on the back of the power supply
Personal Computer Systems
Internal PC Components
 Motherboards
• backbone of the computer
• interconnects computer components
 CPU (PGA, LGA)
• the brain of the computer
• most processing is done by the CPU
 Cooling Systems
• dissipates the heat generated by computer components
 Memory (ROM and RAM)
• RAM: Stores data temporarily, aiding processing
• ROM: Stores data permanently; often storing
firmware and low level programs
Central Processing Unit (con’t.)
 Some CPUs incorporate hyperthreading or hypertransport (AMD
architecture) to enhance the performance of the CPU.
 The amount of data that a CPU can process at one time depends on the size of
the processor data bus (FSB).
 The front side bus (FSB) or system bus is the physical bi-directional data bus
that carries all electronic signal information between the central processing unit
(CPU) and the Northbridge. Some computers also have a back side bus which
connects the CPU to a memory cache.
 Speed of the CPU is measured in cycles per second-megahertz (MHz) or
gigahertz (GHz).
 Overclocking is a technique used to make a processor work at a faster speed
than its original specification.
 The opposite of overclocking is CPU throttling. CPU throttling is a technique
used when the processor runs at less than the rated speed to conserve power
or produce less heat. Throttling is commonly used on laptops and other mobile
devices.
Central Processing Unit (CPU)
 Two major CPU architectures related to instruction sets:
• Reduced Instruction Set Computer (RISC)
• uses a small, highly optimized set of instructions, rather than a more
specialized set of instructions
• Complex Instruction Set Computer (CISC)
• uses a broad set of instructions, resulting in fewer
steps per operation
Central Processing Unit (con’t)

The latest processor technology has resulted in CPU
manufacturers finding ways to incorporate more than one
CPU core onto a single chip.
Dual Core CPU - two cores inside a single CPU
Triple Core CPU - three cores inside a single CPU
Quad Core CPU - four cores inside a single CPU
Hexa-Core CPU - six cores inside a single CPU
Octa-Core CPU - eight cores inside a single CPU
ROM and RAM
 Programmable Read-only memory (PROM)
 Basic instructions for booting the computer and
loading the operating system are stored in ROM.
 ROM chips retain their contents even when the
computer is powered down.
 Information is written to an EEPROM chip after it is
manufactured. EEPROM chips are also called
Flash ROMs. An EEPROM chip can be erased and re-written without having
to remove the chip from the computer. EPROM chips can be erased by
exposure to UV light.
 Random-access memory (RAM)
 RAM is temporary storage for data and programs that are being accessed by
the CPU.
 RAM is volatile memory, which means that the contents are erased when the
computer is powered off.
 More RAM means more capacity to hold and process large programs and files,
as well as enhance system performance.
Memory Modules
 Memory modules are memory chips that have
been soldered on to a special circuit board for
easy installation and removal.
 Dual Inline Memory Module (DIMM) is a circuit
board that holds SDRAM, DDR SDRAM, and
DDR2 SDRAM chips.
 RAM Bus Inline Memory Module (RIMM) is a
circuit board that holds RDRAM chips.
 Small Outline DIMM (SODIMM) is a smaller,
more condensed version of DIMM which provides
random access data storage that is ideal for use
in laptops, printers, and other devices where
conserving space is desirable.
 The speed of memory has a direct impact on how
much data a processor can process because
faster memory improves the performance of the
processor. As processor speed increases,
memory speed must also increase.
Cache and Error Checking
 Cache
• SRAM is used primarily as cache memory to store the most
frequently used data.
• SRAM provides the processor with faster access to the data than
retrieving it from the slower DRAM or main memory.
 Error Checking
• Memory errors occur when the data is not stored correctly in the
RAM chips.
• The computer uses different methods to detect and correct data
errors in memory:
• nonparity (no error-checking bit)
• parity (extra error-checking bit)
• ECC most often used in server
environments
Let’s see what you have learned . . .
Q: Which component controls the communications and
interactions between the CPU and other components on
the motherboard?
A: chipset
Q: Which type of memory is primarily used as cache
memory?
A: SRAM
Q: What type of chip can be erased and re-written without
having to remove the chip from the computer?
A: EEPROM
Q: What is this process called?
A: flashing
Personal Computer Systems
Internal PC Components (cont.)
 Adapter Cards and Expansion Slots
• adapter cards extend computer functionality
• adapter cards connect to the motherboard
through expansion slots
 Storage Devices
• designed to permanently store user data,
user applications and the operating system (PATA,
SATA, Hybrid or SSD)
• Solid state drives (SSDs) do not have moving parts, which results in faster access to data,
higher reliability, reduced power usage.
• can be internal or external to the computer
• generally measured in RPM (revolutions per minute)
 Video Ports
• connects a video system to an external display device such as a monitor or projector
• Video systems are often designed as an adapter card.
 General Ports
• provide connectivity between the motherboard and various external devices such as printers,
external storage and video cameras
Personal Computer Systems
Internal PC Components (cont.)
 Thunderbolt is an
interconnect technology
developed by Intel in
cooperation with Apple.
 Thunderbolt combines
PCI Express and
DisplayPort into a single
connection, allowing for
a combination of up to
six peripherals, like
storage devices and
monitors, to be daisychained together.
RAID Levels
 RAID provides a way to store data across
multiple hard disks for redundancy.
RAID Min # of
Level Drives
Description
0
2
Data striping without redundancy (i/o improvement)
1
2
Disk mirroring (high performance with data protection)
2
2
Error-Correcting Coding
3
3
Byte-level data striping with dedicated parity
4
3
Block-level data striping with dedicated parity
5
3
Block-level data striping with distributed parity
6
4
Independent Data Disks with Double Parity
0/1
4
Combination of data striping and mirroring
10
4
Mirrored set in a striped set
Raid 0 and 1
Raid 5 and 10
Adapter Slots
Size Matters
• PCI—shared bandwidth, which is slower
• PCI-x—uses a 32-bit bus and is 4 times fast than PCI
• PCI-e—point-to-point, serial connection, which allows slots to be
linked together for a faster connection
Ports
• PCI – 133 Mbps, 32 bits,
33 MHz
• AGP – 266 Mbps, 32 bits
wide, 66 MHz
• PCI-e – x1 equates to
1 lane of data transfer
• x16 equates to 16 lanes
of data transfer
Personal Computer Systems
External Ports and Cables
 Video Ports and Related Cables
• A few different standards govern video traffic between the
computer and external video devices.
• HDMI and DisplayPort are examples of video ports that require a specific cable to
operate and are usually connected to high-definition TVs or computers with audio
video devices.
 Other Ports and Related Cables
• Motherboards have a number of other ports used for device
connectivity; USB is a common example.
 Adapters and Converters
•
Adapters and converters can be a solution if a motherboard does not have the proper
port to connect to a device.
•
Adapters do not usually process the signal; they simply redirect it to another pin.
•
Converters are more likely to process and transform the signal, converting
it to be accepted by an existing port.
Select Computer Components
Select PC Components
 Select the Motherboard, CPU, Case and Memory
• CPU, memory, motherboard and case choices are interrelated.
• The motherboard should support all customer
required applications and still fit properly in the case.
• The case should host the motherboard, the proper
power supply and provide good airflow for the
internal components.
• The CPU must be compatible with motherboard CPU
slot and voltage; it should be compatible with the
chosen memory speed for maximum
performance.
• The memory must also be compatible with motherboard
memory slots and voltage. The speed of the RAM must be supported
by the chipset.
• The amount of memory will depend on the type of applications
requested by the customer.
Select Computer Components
Select PC Components (cont.)
 Select the Case and Fans
• Case and fans must be chosen to maximize internal airflow.
• The fans must fit the case and be within the power limits provided by
the power supply.
 Select the Power Supply
• The power supply should be selected based on the maximum amount of
power required by all the internal components.
• Remember that some components will draw more power while under
heavy load.
 Select Adapter Cards
• Make sure the motherboard has compatible expansion slots to
support the adapter cards.
• The motherboard must also have enough expansion slots to
receive all the required adapter cards.
• Customer needs will define what adapter cards must be procured
and installed.
Select Computer Components
Select PC Components (cont.)
 Select Hard Drives
• Important hard drive factors to be considered are speed,
storage space and communication interface type.
• The drive’s underlying technology (HDD vs Hybrid vs
SSD) directly impacts speed.
 Select a Media Reader
• The media reader must be compatible with customer
media.
 Select Optical Drives
• Make sure the drive is compatible with customer media.
• Other factors to consider are speed, communication
interface type and the ability to write to the media.
Hard Drive Connectors
 PATA (Parallel ATA) hard drives:
• originally called ATA (Advanced Technology Attachment)
• with the introduction of SATA, ATA was renamed to PATA
• can use a 40-pin / 80-conductor cable or a 40-pin / 40conductor cable
 SATA (Serial ATA) hard drives:
• connect to the motherboard using a serial interface
• have a higher data-transfer rate than PATA drives
• smaller data cable allows for improved airflow
• eSATA (external SATA)
 SCSI (Small Computer Systems Interface) hard drives:
• use a 50-pin, 68-pin, or 80-pin connector
• Up to 15 SCSI drives can be connected to a SCSI drive
controller.
Select Computer Components
Select PC Components (cont.)
 Select External Storage
• Important factors when selecting external storage are
storage space, speed and communication interface.
• Make sure the computer has enough ports to
accommodate the external devices and peripherals.
• Note: Some external devices do not require an external
power supply but rely on a second USB port for power.
 Select I/O Devices
• The selection of I/O devices is application specific and
will depend on customer requirements.
• Make sure the computer has enough communication
ports and that they are compatible with the types
required by the I/O devices.
Ports and Cables
 Serial ports transmit one bit of data at a time.
 A telephone cable (RJ11) is used to connect a
modem to a telephone outlet.
 USB is a standard interface for connecting hotswappable peripheral devices to a computer.
Some devices can also be powered through the
USB port. A single USB port in a computer can
support up to 127 separate devices with the use of
multiple USB hubs.
• USB 1.0 (12 Mbps), 2 (480 Mbps), 3 (4.8 Gbps)
 FireWire is a high-speed, hot-swappable interface
that can support up to 63 devices. Some devices
can also be powered through the FireWire port.
• The IEEE 1394a standard supports data rates up to 400
Mbps and cable lengths up to 15 feet (4.5 m). This
standard uses a 6-pin connector or a 4-pin connector.
• The IEEE 1394b standard supports data rates in excess
of 800 Mbps and uses a 9-pin connector.
 A parallel cable (IEEE1294) is used to connect
parallel devices, such as a printer or scanner, and
can transmit 8 bits of data at one time.
Input Devices
 Input devices are used to enter data or
instructions into a computer:
• mouse and keyboard
• KVM switch
• gamepad and joystick
• digital camera and digital video camera
• biometric authentication device
• touch screen
• scanner
Output Devices
 Monitors and Projectors:
• Liquid crystal display (LCD) is commonly
used in laptops and some projectors. LCD
comes in two forms, active matrix and
passive matrix.
• A light-emitting diode (LED) display is an
LCD display that uses LED backlighting to
light the display.
• An Organic LED (OLED) display uses a
layer of organic material that responds to
electrical stimulus to emit light.
Output Devices (Terms)
 Pixel - The term pixel is an abbreviation for picture element. Pixels are the tiny dots
that comprise a screen. Each pixel consists of red, green, and blue (RGB).
 Dot pitch - Dot pitch is the distance between pixels on the screen. A lower dot pitch
number produces a better image.
 Contrast ratio - The contrast ratio is a measurement of the difference in intensity of
light between the brightest point (white) and the darkest point (black). A 10,000:1
contrast ratio shows dimmer whites and lighter blacks than a monitor with a contrast
ratio of 1,000,000:1.
 Refresh rate - The refresh rate is expressed in Hertz (Hz) and refers to how often per
second the image is rebuilt. A higher refresh rate produces a better image.
 Aspect ratio - Aspect ratio is the horizontal to vertical measurement of the viewing
area of a monitor. For example, QSXGA measures 2,560 pixels horizontally by 2048
pixels vertically which creates an aspect ratio of 5:4. If a viewing area was 16 inches
wide by 12 inches high, then the aspect ratio would be 4:3. A viewing area that is 24
inches wide by 18 inches high also has an aspect ratio of 4:3.
 Native resolution - Native resolution is the number of pixels that a monitor has. A
monitor with a resolution of 1280x1024 has 1280 horizontal pixels and 1024 vertical
pixels. Native mode is when the image sent to the monitor matches the native
resolution of the monitor.
Configurations for Specialized Computer Systems
Specialized Computer Systems
 Thick and Thin Clients
• Thin clients have little processing power and are designed to act as a terminal to a
server (thick client).
• Thick clients have more powerful CPUs, more memory and their own storage. They
serve as processing stations for thin clients.
 CAx Workstations
• designed to support CAD and CAM applications
• plenty of RAM, fast disks, powerful CPU and special
input devices are common resources.
 Audio and Video Editing Workstations
• common editing workstation resources include
much RAM, fast disks, powerful CPU and
special adapter cards such as audio and video capture.
Configurations for Specialized Computer Systems
Specialized Computer Systems (cont.)
 Virtualization Workstations
• These workstations are designed to run virtual computers
• Virtual computers use and share the workstation’s physical resources such as CPU,
memory and disks.
• The selection of physical resources will depend on the number and purpose of the
virtual machines. Powerful CPU and sufficient RAM are suggested.
 Gaming PCs
• Due to high resource requirements of modern games, gaming PCs are very resource
demanding.
• A few requirements of gaming PCs are: top end CPU, lots of
fast RAM, fast disks, high performance input devices and audio
systems.
 Home Theatre PCs
• These computers must be able to play various media formats
and, in some cases, receive TV signals.
• Common HTPC requirements include powerful CPU, fast RAM, large disks,
fast NIC and video card with TV input.
Let’s see what you have learned . . .
Q: Name a storage device that uses magnetic medium
for storing data.
A: hard drive
Q: Which two pieces of information are needed before
selecting a power supply?
A: the form factor of the case and the total wattage of
all the components
Q: Which RAID level has the highest performance
without redundancy?
A: RAID 0
Chapter Summary
Summary
 This chapter introduced the components that comprise a personal computer system and
what to consider when choosing upgrade components.
 Information technology encompasses the use of computers, network hardware, and
software to process, store, transmit, and retrieve information.
 A personal computer system consists of hardware components and software applications.
 The computer case and power supply must be chosen carefully to support the hardware
inside the case and allow for the addition of components.
 The internal components of a computer are selected for specific features and functions. All
internal components must be compatible with the motherboard.
 Use the correct type of ports and cables when connecting devices.
 Typical input devices include the keyboard, mouse, touch screen, and digital cameras.
 Typical output devices include monitors, printers, and speakers.
 Cases, power supplies, the CPU and cooling system, RAM, hard drives, and adapter
cards, must be upgraded when devices fail or no longer meet customer needs.
 Specialized computers require hardware specific to operate. The type of hardware used in
specialized computers is determined by how a customer works and what a customer wants
to accomplish.
Assignments
 Carefully read Chapter 1 completing any interactive activities
included and watching any embedded videos.
 View the 2 NewEgg videos and complete the quiz
 Go to http://www.professormesser.com/free-a-plus-training/220801/an-overview-of-motherboard-types/. Watch the video about
motherboard types. Write up a summary that includes your name,
the name of the video (“An Overview of Motherboard Types”), and a
five- to six-sentence paragraph summarizing the video. Save as
Professor Messer Video No. 1.
 Complete worksheet 0.2.2.2—Job Opportunities
 Complete worksheet 1.1.1.4—Ohm’s Law
 Complete worksheet 1.2.1.13—Research Computer Components
 Complete worksheet 1.3.1.7—Build a Specialized Computer System