Chapter 1
Computer Hardware
1
What’s inside and on the CD?
•
In this chapter, you will:
– Gain an overview of computer equipment and
terminology
– Learn how computers are classified
– Learn how personal computers fit into the gamut of
machines from PDAs to supercomputers
– Review basics components of a typical personal
computer system
– Look inside the system unit
– Explore advantages and disadvantages of several
computer storage devices
– Learn some basics about maintaining your
computer and troubleshooting problems
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What is a computer?
• A device that:
– Accepts input
– Processes data
– Stores data
– Produces output
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What is a computer?
• Computer input is whatever is typed, submitted, or
transmitted to a computer system
• Data refers to symbols that represent facts, objects, and
ideas
• Processing is manipulation of data
– Most takes place in central processing unit (CPU), a
computer’s “brain”
– Computer programs are instructions that tell
computers how to process
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What is a computer?
• An operating system is software that helps a computer
operate efficiently and keep track of data
• Application software helps users “apply” computers to
specific tasks
• Memory is temporary storage
• Storage is permanent
• Computer output is results produced by computer
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What is a computer?
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How are computers classified?
• Computers are divided into five categories:
– Handheld computers
– Personal computers
– Servers
– Mainframe computers
– Supercomputers
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How are computers classified?
• Handheld computer (PDA) features include:
–
–
–
–
Small keyboard or touch-sensitive screen
Designed to fit in your pocket
Runs on batteries
Used while holding it
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How are computers classified?
• A personal computer is designed to meet
the computing needs of an individual
• Desktop computers fit on desks and run
on power from wall outlets
• A Notebook computer (laptop)
incorporates screen, keyboard, storage,
and processing
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How are computers classified?
• A tablet computer is portable, featuring
a touch-sensitive screen used for
writing or drawing
•
A server is to serve data to computers
connected to a network
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How are computers classified?
• A mainframe computer is capable of
simultaneously processing data for hundreds
or thousands of users
• A supercomputer is one of the fastest
computers in the world and can tackle
complex tasks
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Can computers connect to each other?
• A PDA can connect to desktop with a cable or wireless
link
• Personal computers can connect to each other or larger
computers via wired or wireless computer networks
• A computer network can be as few as two or as many as
thousands of computers
• The Internet is the world’s largest network, connecting
millions of computers
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Can computers connect to each other?
• Computers can be connected using a centralized model
or a distributed model
• A Centralized computing system depends on a
centrally-located computer for processing and storage
• A distributed computer network spreads the
processing and storage tasks among many computers
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Can computers connect to each other?
Centralized computer
system
Distributed computer
network
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Can computers connect to each other?
• Large-scale centralized and distributed computer
systems are used for many tasks:
– Government applications include tax roles, census
records, and vehicle registration
– Commercial applications include inventory, payroll,
and point-of-sale
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Can computers connect to each other?
• Large-scale centralized and distributed computer
systems are used for many tasks (cont’d):
– Hospital and healthcare organizations applications
include patient records, integrated diagnostic tools,
patient billing, and health insurance claims
processing
– In education, applications include course registration,
student records, budgeting, and payroll
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What are the components of a
personal computer system?
• Included in a typical personal computer system are:
• System unit
• Display device
• Keyboard
• Mouse
• Storage devices
• USB ports
• Sound card and speakers
• Modem
• Network card
• Printer
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What are the components of a
personal computer system?
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What’s inside the system unit?
• The System contains storage devices, a power supply,
and main circuit board (motherboard)
• “Computer chip”, “microchip”, and “chip” are technical
jargon for an integrated circuit
• An integrated circuit is a super-thin slice of semiconducting material packed with microscopic circuit
elements
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What’s inside the system unit?
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How do computer circuits manipulate
data?
• Most computers are electronic, digital devices
– Digital devices work with discrete data, such as
digits 1 and 0, or like a light switch – on or off
– Analog devices work with continuous data, like a
dimmer switch with continuous range
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How do computer circuits manipulate
data?
• Most computers use simplest technology of two possible
states, like on-off switch
• Usually we indicate “on” state as 1 and “off” state as 0
• These 1s and 0s are referred to as binary digits or
shortened to bits
• Computers use sequences of bits to digitally represent
numbers, letters, punctuation marks, music, pictures,
and videos
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How do computer circuits manipulate
data?
• Computers employ several codes to represent character
data, including:
– ASCII – requires only seven bits for each character
– Extended ASCII – requires eight bits for each
character
– EBCDIC – is eight-bit technology used on older, IBM
mainframe computers
– Unicode uses sixteen bits and provides code for
65,000 characters
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How do computer circuits manipulate
data?
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What factors affect computer speed,
power and compatibility?
• Computers have three major components:
– Processor
– Memory
– Storage
• When a program is started, it is moved from storage to
memory
• The processor fetches program instructions from
memory, then begins to execute
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What factors affect computer speed,
power and compatibility?
• If instructions require data, the processor fetches it from
memory, loads it into memory, then transfers it to the
processor
• The results are sent back to memory
• The results can be stored or sent to output printer or
screen
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What factors affect computer speed,
power and compatibility?
• Speed and efficiency of processing cycle can be affected
by factors such as:
– Microprocessor type and speed
– Memory capacity
– Hard disk drive speed and organization
– Display capability and video memory
– Network and modem connection speed
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What factors affect speed and power?
• Bit is abbreviated as lowercase “b”
• Byte is composed of eight bits and is abbreviated by
uppercase “B”
• These abbreviations combined with kilo produce
specifications such as KB (kilobyte) and Kb (kilobit)
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What factors affect speed and power?
• In world of computers kilo means 1024, not 1000
• Kilobit is 1024 bits and kilobyte is 1024 bytes
• Kilobytes is often used when referring to size of small
computer files
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What factors affect speed and power?
• Prefix “mega” means a million, or in context of bits and
bytes, 1,048,576
• Megabits is used when referring to speed of data
transmission
• Megabytes is used when referring to file size, CD
capacity, or video card memory capability
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What factors affect speed and power?
• Giga refers to a billion or 1,073,741,824
• Gigabytes are used to describe RAM, DVD, and hard
disk capacity
• Mainframe and supercomputers use tera- (trillion), peta(quadrillion), and exa- (quintillion)
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What factors affect speed and
power?
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What factors affect speed and power?
• The three most popular personal computer platforms are
PCs, Macs, and Linux
• The PC platform is based on the design of the IBM PC
• The Mac platform is based on a proprietary design for the
Macintosh
• The Linux platform is a standard PC with the Linux
operating system
• Compatible computers operate in essentially the same
way
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What’s important about
microprocessors?
• The most important, and usually the most expensive,
component of a computer
• Circuitry is grouped into important functional areas
– ALU ( arithmetic logic unit) performs arithmetic
operations
• Uses registers to hold data that is being
processed
– Control unit fetches each instruction
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What’s important about
microprocessors?
• Microprocessor speed is measured in megahertz (MHz)
or gigahertz (GHz)
– MHz = 1 million cycles per second
– GHz = 1 billion cycles per second
• During each cycle the microprocessor executes
instruction
• The faster the clock speed, the more instructions
executed per second
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What’s important about
microprocessors?
• Microprocessors are also rated by word size
– Many process a 32-bit word
– 64-bit available, and are faster then 32-bit units
• Microprocessors manufactured by several companies:
– Intel
– AMD
– Motorola
– IBM
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What’s important about
microprocessors?
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What’s important about computer
memory?
• RAM (random access memory) is temporary holding
area for data, application programs instruction, and
operating system
• RAM is “waiting room” for processor
• When program is started, it is held in RAM until needed
and remains there until program is closed
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What’s important about computer
memory?
• RAM also holds data
• Most RAM is volatile, which means it needs electrical
power to hold data
• If power goes out, or computer is turned off, data stored
in RAM is instantly and permanently lost
• It is important to frequently save work to a permanent
storage area, such as hard disk, as you work
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What’s important about computer
memory?
• RAM also holds operating system instructions, loaded
each time you turn on your computer and held until it is
turned off
• RAM capacity is measured in megabytes or gigabytes
• Today’s computers have between 512 megabytes and 4
gigabytes of RAM
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What’s important about computer
memory?
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What’s important about computer
memory?
• Most computers also contain ROM (read only
memory) – a type of memory that holds the computers
startup routine
• Whereas RAM is temporary and volatile, ROM is
permanent and non-volatile
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Why do computers use multiple
storage devices?
- Computers feature multiple storage devices such as:
- Hard disk drive is the main storage device in most
computers
• Provides lots of storage capacity
• Provides fast access to files
• Economical
• Capacity is measured in gigabytes and speed in
milliseconds (ms) or revolutions per minute (RPM)
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Why do computers use multiple
storage devices?
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Why do computers use multiple
storage devices?
• A CD (compact disk) provides 650-700 MB of storage
• A DVD (digital video disk or digital versatile disk) is a
variation with a capacity of 4.7 GB
– CDs and DVDs are durable storage
– Unaffected by magnetic fields
– Dust and dirt can be cleaned off
– Biggest threat are scratches
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Why do computers use multiple
storage devices?
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Why do computers use multiple
storage devices?
• CDs and DVDs come in several varieties:
– Read only (ROM) – permanent data stored during
manufacturing
– Recordable (R) – A writable drive can store data but
it can’t be changed
– Rewritable (RW) – can be changed many times,
much like a hard drive but much slower
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Why do computers use multiple
storage devices?
• A USB flash drive is a popular removable,
portable storage device
– About the size of a highlighter pen
– Very durable
– Open, edit, delete, and run files just as if
they were on hard drive
– Plugs into USB port
– Provides fast access to data and uses
little power
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Why do computers use multiple
storage devices?
• In addition to storage devices connected to computer,
data can be stored on online storage
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What kind of protection and
maintenance does a computer require?
• Large organizations protect equipment from theft with
high-tech security systems
• Protect personal computer by locking to desk or locking
room
• When traveling by air, carry it in your carry-on bag
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What kind of protection and
maintenance does a computer require?
• Make sure computer is balanced safely on desk or
resting on floor
• When carrying notebook computer, use padded carrying
case
• When transporting desktop, use original box or protect it
with foam padding
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What kind of protection and
maintenance does a computer require?
• Environmental factors can do damage
– Excess heat can damage circuitry
– Excess humidity combined with salt air can corrode
contacts
– Magnetic fields can erase data
– Dust and dirt can cause overheating and clog up
mechanical parts
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What kind of protection and
maintenance does a computer require?
• Routine cleaning of mouse and keyboard can keep them
working smoothly
• Follow manufacturer’s instructions for cleaning to keep
printer from jamming and print head from smearing
• Keep floppy disks and hard disks away from strong
magnetic fields
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What kind of protection and
maintenance does a computer require?
• Computers are vulnerable to power irregularities
– Make sure power cable is positioned so it can’t be
accidentally disconnected
– When going to another country, ensure your
equipment conforms to power systems
– Use surge strips to protect against power spikes
and surges
– To protect against power outages, you can connect to
uninterruptible power supply
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What kind of protection and
maintenance does a computer require?
• Owners should periodically make backups of data, run a
defragmentation utility, and update virus checking
software
• Consider following guidelines when troubleshooting:
– Make sure equipment is plugged in
– Check all cables
– Get clear idea of problem by trying to isolate
malfunctioning device or replicating steps
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What kind of protection and
maintenance does a computer require?
– Attempt basic solutions, such as restart device or
rebooting
– Look for information in manuals, the Web, or
manufacturer’s support line
– When communicating with technicians, explain problem
accurately and prepare to answer questions about
brand, model, operating system, and application
software
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What kind of protection and
maintenance does a computer require?
– Follow instructions carefully and completely
– Before you resume normal operations, make sure
problem is fixed
– If possible, take steps to avoid similar problems in the
future
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