CHAPTER 2
Computer Hardware
2 Chapter Contents
Section A: Data Representation and Digital
Electronics
Section B: Microprocessors and Memory
Section C: Storage Devices
Section D: Input and Output Devices
Chapter 2: Computer Hardware
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2
SECTION
Section A: Data Representation and Digital
Electronics
A
Data Representation
Quantifying Bits and Bytes
Digital Electronics
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2 Data Representation
Process of transforming diverse data into a
form computers can use for processing
Digital devices work with distinct and
separate data
Analog devices work with continuous data
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2 Data Representation
Numeric data
– Binary number system
Character data
– ASCII, Extended ASCII, and Unicode (not used in
arithmetic operations)
Digitizing is the process of converting analog
data into digital format
File headers contain information about the
code used to represent file data
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2 Data Representation
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2 Quantifying Bits and Bytes
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2 Digital Electronics
Bits take the form of electrical pulses that can
travel over circuits
System unit
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2 Digital Electronics
An integrated circuit (computer chip) is a
super-thin slice of semiconducting material
packed with microscopic circuit elements
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2 Digital Electronics
The computer’s main circuit board is called
the system board, or motherboard
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2
SECTION
B
Section B: Microprocessors and Memory
Microprocessor Basics
Microprocessor Performance Factors
Today’s Microprocessors
Random Access Memory
Read-only Memory
CMOS Memory
Buying a Computer
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2 Microprocessor Basics
A microprocessor is an integrated circuit
designed to process instructions
– ALU
– Registers
– Control unit
– Instruction set
(list of instructions
a microprocessor
can perform)
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2 Microprocessor Performance Factors
 Microprocessor clock (sets pace for executing instructions)
– Megahertz (millions of cycles per second)
– Gigahertz (billions of cycles per second)
 Word size (# of bits a processor can manipulate at a time)
 Cache (high speed memory where a processor can access data
quicker than memory located elsewhere)
– Level 1 cache (L1)
– Level 2 cache (L2)
 CISC vs. RISC technology
– CISC- complex instruction set computer
– RISC- reduced instruction set computer. RISC is faster than CISC
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2 Microprocessor Performance Factors
Serial processing- processor completes all
steps in the instruction cycle before it begins
to execute the next instruction
– Pipelining
Parallel processing
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2 Microprocessor Performance Factors
Dual core processors contain the circuitry for
two microprocessors
Benchmark tests gauge the overall speed of
a microprocessor
A microprocessor can operate at full
efficiency only if all components in the
computer can handle the faster speeds.
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2 Today’s Microprocessors
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2 Random Access Memory
Random Access Memory is a temporary
holding area for data, application program
instructions, and the operating system
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2 Random Access Memory
Microscopic capacitors hold the bits that
represent data
Most RAM is volatile
– Requires electrical power to hold data
– Usually consists of several chips
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2 Random Access Memory
RAM capacity is expressed in megabytes or
gigabytes
Personal computers typically feature between
128 MB and 2 GB of RAM
An area of the hard disk, called virtual
memory, can be used if an application runs
out of allocated RAM
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2 Random Access Memory
RAM speed is often expressed in nanoseconds or
megahertz
SDRAM is fast and relatively inexpensive
– DDR
RDRAM is more expensive, and usually found in
high-performance workstations
“Waiting room” for the processor
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2 Read-Only Memory
ROM is a type of memory circuitry that holds
the computer’s startup routine
– Permanent and non-volatile
The ROM BIOS tells the computer how to
access to hard disk, find the operating
system, and load it into RAM
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2 CMOS Memory
Stores basic system information
More permanent than RAM, and less
permanent than ROM
Requires very little power to hold data
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2 Buying a Computer
Assess your budge
Think about how you plan to use your
computer
Look at ads and visit online computer stores
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2
SECTION
C
Section C: Storage Devices
Storage Basics
Floppy Disk Technology
Hard Disk Technology
Tape Storage
CD and DVD Technology
Solid State Storage
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2 Storage Basics
A storage medium contains data
A storage device records and retrieves data
from a storage medium
– Data gets copied from a storage device into
RAM, where it waits to be processed
– Processed data is held temporarily in RAM
before it is copied to a storage medium
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2 Storage Basics
Magnetic storage stores data by magnetizing
microscopic particles on the disk or tape
surface
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2 Storage Basics
Optical storage stores data as microscopic
light and dark spots (land and pits) on the
disk surface
– CD and DVD storage technologies
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2 Storage Basics
Solid state storage technology stores data in
a non-volatile, erasable, low-power chip
– Some solid state storage requires a card reader
to transfer data to or from a computer
– Faster than optical or magnetic storage
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2 Storage Basics
Most desktop computers have
several drive bays, some
accessible from outside the
case, and others—designed for
hard disk drives—without any
external access. Empty drive
bays are typically hidden from
view with a face plate.
CLICK TO START
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2 Storage Basics
Versatility
Durability
Speed
– Access time (often measured in milliseconds and is how
long it takes a computer to locate data on storage
medium and read it)
– Random vs. sequential access
– Data transfer rate
Capacity
– Kilobytes (KB), megabytes (MB), and gigabytes
frequently used today
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2 Floppy Disk Technology
Used for standard HD DS disks and Zip disks
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2 Hard Disk Technology
Hard disk platters are sealed
inside the drive case or
cartridge
to prevent dust and other
contaminants from interfering
with the read-write heads.
CLICK TO START
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2 Hard Disk Technology
A controller positions the disk and read-write
heads to locate data
– SATA
– Ultra ATA
– EIDE
– SCSI
Not as durable as many other storage
technologies
– Head crash
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2 Tape Storage
A tape backup stores a copy of the data on a
hard disk on a magnetic tape
A tape is a sequential storage medium
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2 CD and DVD Technology
A CD can hold up to 80 minutes of music or
700 MB of data
A DVD can hold about 4.7 GB of data
A double-layer DVD can store 8.5 GB of data
HD-DVDs can store 15 GB
Blu-ray DVDs can store 25 GB
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2 CD and DVD Technology
CD-DA
DVD-Video
CD-ROM
DVD-ROM
CD-R
DVD+R or DVD-R
CD-RW
DVD+RW or DVD-RW
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2 CD and DVD Technology
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2 Solid State Storage (Portable)
USB flash drive
CompactFlash (CF) cards
MultiMedia cards (MMC)
SecureDigital (SD)
SmartMedia (least durable)
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2
SECTION
D
Section D: Input and Output Devices
Basic Input Devices
Display Devices
Printers
Installing Peripheral Devices
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2 Basic Input Devices
Keyboard
Pointing device
– Pointing stick
– Trackpad
– Trackball
– Joystick
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2 Display Devices
 A CRT display device uses
a bulky glass tube (least
expensive)
 An LCD manipulates light
within a layer of liquid
crystal cells
 Plasma screen technology
illuminates lights arranged
in a panel-like screen
 On most monitors, the
viewable image does not
stretch to the edge of the
screen
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2 Display Devices
Viewable image size
Dot pitch
Viewing angle width
Refresh rate
Color depth
Resolution
– VGA, SVGA, XGA, SXGA, and UXGA
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2 Display Devices
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2 Display Devices
Graphics circuitry generates the signals for
displaying an image on the screen
– Integrated graphics
– Graphics card
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2 Printers
An ink-jet printer has a nozzle-like print head
that sprays ink onto paper
A laser printer works like a photocopier
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2 Printers
Laser printers are a popular
technology when high-volume
output or good-quality printouts
are required.
CLICK TO START
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2 Printers
Dot matrix printers produce characters and
graphics by using a grid of fine wires
– The wires strike a ribbon and the paper
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2 Printers
Other printer technologies include solid ink printers,
thermal transfer printers, and dye sublimation
printers
Printer features
–
–
–
–
–
–
Resolution
Print speed
Duty cycle
Operating costs
Duplex capability
Memory
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2 Installing Peripheral Devices
The data bus moves data within the computer
The expansion bus is the segment of the data bus
that extends between RAM and peripheral devices
Expansion cards are small circuit boards that give
the computer additional capabilities
– Expansion slot
• ISA (Old technology. Slower devices, not found on most new
computers)
• PCI (32 or 64 bit. Graphics cards, network cards, and more)
• AGP (Primarily used for graphics cards)
• PCMCIA (Used in notebook computers)
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2 Installing Peripheral Devices
An expansion card simply slides
into an expansion slot and is
secured with a small screw. Before
you open the case, make sure you
unplug the computer and ground
yourself—that’s technical jargon
for releasing static electricity by
using a special grounding wristband
or by touching both hands to a metal
object.
CLICK TO START
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2 Installing Peripheral Devices
An expansion port
passes data in and out
of a computer or
peripheral device
Peripheral device may
include the Plug and
Play feature, or require
a device driver
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2 Installing Peripheral Devices
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CHAPTER 2 COMPLETE
Computer Hardware