The document discusses the major components of computer systems, including different types of computers, hardware components, and storage devices. It defines what a computer is and describes the functions of input, processing, output, storage, and control. It also covers topics like computer processing speeds, memory types, storage media, and optical disks.

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Computer Hardware
Chapter
3

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1. Identify the major types and uses of
microcomputer, midrange, and
mainframe computer systems.
2. Outline the major technologies and uses
of computer peripherals for input, output,
and storage.
Learning Objectives

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Learning Objectives
3. Identify and give examples of the
components and functions of a computer
system.
4. Identify the computer systems and
peripherals you would acquire or
recommend for a business of your
choice, and explain the reasons for your
selections.

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What is a Computer?
Definition:
• All computers are systems of input,
processing, output, storage, and control
components.

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Types of Computer Systems

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Microcomputer Systems
• Personal Computer (PC) – microcomputer
for use by an individual
• Professional Workstation – a powerful,
networked PC for business professionals
• Laptop – small, portable PC

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Microcomputer Systems
• Network Server – more powerful
microcomputers that coordinate
telecommunications and resource sharing
in small local area networks and Internet
and intranet websites
• Computer Terminals – depend on servers
for software, storage and processing
power

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Microcomputer Systems
• Network Computers – low-cost, sealed
microcomputers with no or minimal disk
storage that are linked to the network
• Information Appliances – hand-held
microcomputer devices

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PC Features

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Midrange Systems
Definition:
• Primarily high-end network servers and
other types of servers that can handle the
large-scale processing of many business
applications.

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Mainframe Systems
Definition:
• Large, fast, and powerful computer
systems

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Supercomputer Systems
Definition:
• Extremely powerful computer systems
specifically designed for scientific,
engineering, and business applications
requiring extremely high speeds for
massive numeric computations

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Hardware Organized by System Functions
• Input Devices convert data into electronic
form for direct entry or through a
telecommunications network into a
computer system
• Processing Components primarily the
Central Processing Unit (CPU)
• Arithmetic-Logic Unit (ALU) - perform
arithmetic and logic functions required to
execute software instructions

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Hardware Organized by System Functions
• Output Devices convert electronic information
produced by the computer system into human-
intelligible form for presentation to end users
• Storage Devices store data and software
instructions needed for processing
• Control Components primarily the CPU’s
Control Unit which interprets software
instructions and transmits directions that control
the activities of the other components of the
computer system

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Computer Processing Speeds
• Millisecond – thousandth of a second
• Microsecond – millionth of a second
• Nanosecond – billionth of a second
• Picosecond – trillionth of a second

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Computer Clock Speeds
• MIPS – million instructions per second
• Megahertz (MHz) – millions of cycles per
second
• Gigahertz (GHz) – billions of cycles per
second

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Throughput
Definition:
• Ability of a microprocessor to perform useful
computation or data processing assignments
during a given period of time
Depends on:
• Buses – size of circuitry paths that interconnect
microprocessor components
• Registers – that process instructions
• Cache – high-speed memory
• Specialized Processors

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Computer Peripherals
Definition:
• Generic name given to all input, output,
and secondary storage devices that are
part of a computer system, but are not
part of the CPU.

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Peripherals Advice

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Online vs. Offline
• Online – devices are separate from but
can be electronically connected to and
controlled by a CPU
• Offline – devices are separate from and
not under the control of the CPU

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Input Technologies
• Keyboard
• Pointing Devices
• Pen-Based Computing
• Speech Recognition Systems
• Optical Scanning

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Graphical User Interface (GUI)
Definition:
• Icons, menus, windows, buttons, bars, etc
used for user selection

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Pointing Devices
• Electronic Mouse – Moving mouse on pad
moves cursor on screen. Pressing buttons on
mouse activates activities represented by
selected icons.
• Trackball – Stationary device with a roller ball
on top used to move cursor on screen.
• Pointing Stick – Small button-like device which
moves cursor in direction of pressure placed on
stick.

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Pointing Devices
• Touchpad – Small rectangular touch-
sensitive surface which moves the cursor
in the direction of finger moves on the
pad.
• Touch Screen – Video display screen that
emits a grid of infrared beams, sound
waves, or a slight electric current that is
broken when the screen is touched.

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Pen-based Computing
Definition:
• Pressure-sensitive layer under slate-like
liquid crystal display screen and software
that digitizes handwriting, hand printing,
and hand drawing

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Speech Recognition Systems
• Discrete – user must pause between each
spoken word
• Continuous – software can recognize
conversationally-paced speech

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Optical Scanning
Definition:
• Devices that read text or graphics and
convert them into digital input for your
computer

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Optical Character Recognition (OCR)
Definition:
• The machine identification of printed
characters through the use of light-
sensitive devices

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Other Input Technologies
• Magnetic Stripe – devices that read data
stored in the magnetic stripe on the back
of cards
• Smart Cards – devices that read a
microprocessor chip embedded in a card

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Other Input Technologies
• Digital cameras – devices that allow you
to capture, store, and download still
photos and full motion pictures
• Magnetic Ink Recognition (MICR) –
devices that can read characters printed
on source documents with an iron oxide-
based ink

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Output Technologies
• Video Output
• Printed Output
• Voice Response

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Video Output
• Cathode Ray Tube (CRT) – similar to
vacuum tubes in television
• Liquid Crystal Display (LCD) – electronic
visual displays that form characters by
applying an electrical charge to selected
silicon crystals

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Printed Output
• Inkjet Printers – spray ink onto the page
• Laser Printers – use an electrostatic
process similar to a photocopying
machine

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Storage Trade-Offs

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Binary Representation
Definition:
• Data are processed and stored in a
computer system through the presence or
absence of electronic or magnetic signals
in the computer’s circuitry or in the media
it uses

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Bit vs. Byte
• Bit – binary digit, which can have a value
of either zero or one
• Byte – basic grouping of bits that the
computer operates as a single unit,
typically eight bits

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Storage Capacities
• Kilobyte (KB) – one thousand bytes
• Megabytes (MB) – one million bytes
• Gigabytes (GB) – one billion bytes
• Terabytes (TB) – one trillion bytes
• Petabytes (PB) – one quadrillion bytes

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ASCII Codes

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Binary Number System
Definition:
• Number system used by computers to
perform computations since it has only
two digits

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Binary Number System

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Direct vs. Sequential Access
• Direct (or Random) Access – Each
storage position has a unique address.
Each storage position can be individually
accessed without having to search
through other storage positions.
• Sequential Access – Data are recorded
one after another in a predetermined
sequence. Locating an individual item of
data requires searching the recorded data
until the desired item is located.

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Direct vs. Sequential Access

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Semiconductor Memory
Characteristics:
• Small
• Fast
• Shock Resistant
• Temperature Resistant
• Volatile – contents of memory is lost when
power is interrupted
• Used for Primary Storage

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RAM vs. ROM
• Random Access Memory (RAM) – each
memory position can be both sensed and
changed
• Read Only Memory (ROM) – can be read
but not erased or overwritten

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Firmware
Definition:
• Frequently used programs which are
permanently burned into ROM during
manufacture

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Magnetic Disks
Characteristics:
• Fast
• Large
• Reasonably Priced
• Used for Secondary Storage

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Types of Magnetic Disks
• Floppy Disks – single disk inside a
protective jacket
• Hard Disk Drives – several disks, access
arms and read/write heads in a sealed
module
• Redundant Arrays of Independent Disks
(RAID) - disk arrays of interconnected
microcomputer hard disk drives

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Formatting Disks

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Hard Disk Drives

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Magnetic Tape
Definition:
• Read/write heads of magnetic tape drives
record data in the form of magnetized
spots on the iron oxide coating of the
plastic tape

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Optical Disks

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Optical Disks

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Business Applications of Optical Disks
• Long-term archival storage of historical
files of document images
• Publishing medium for fast access to
reference materials in a convenient
compact form
• Computer video games, educational
videos, multimedia encyclopedias and
advertising presentations

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Summary
• Major types of computers include
microcomputers, midrange computers,
mainframe computers and
supercomputers.
• A computer is a system of information
processing components that perform
input, processing, output, storage, and
control functions.

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End of Chapter
Chapter
3