Computer Hardware
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In this lecture, we will study:
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The hardware components of an
information system:
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CPU (central processing unit)
Memory (primary and secondary storage)
Input devices
Output devices.
The classification of computers by power.
Strategic issues regarding hardware.
1
The Central Processing Unit
(CPU)
The CPU
Input
Devices
Control
ALU
Unit
Registers
Primary
Storage
Output
Devices
Communication
Devices
Secondary
Storage
2
The CPU (continued)
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A microprocessor that executes
instructions to perform processing
tasks. Component parts are:
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Control Unit
Arithmetic-Logic Unit
Registers
Primary Storage
The CPU
Control
ALU
Unit
Registers
Primary
Storage
3
The CPU (continued)
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Control Unit
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Access program
instructions
Decode (interpret)
instructions
Control flow of data
throughout system
Data flows through paths
called buses
The CPU
Control
ALU
Unit
Registers
Primary
Storage
4
The CPU (continued)
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Arithmetic-Logic Unit
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Perform computations on data
Perform comparisons on data
The CPU
Control
ALU
Unit
Registers
Primary
Storage
5
The CPU (continued)
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Registers
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High speed storage areas
Hold data and instructions
The CPU
Control
ALU
Unit
Registers
Primary
Storage
6
The CPU (continued)
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Primary Storage (Main Memory)
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Stores instructions from programs
Stores data to be processed
The CPU
Control
ALU
Unit
Registers
Primary
Storage
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The CPU (continued)
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Machine Instruction Cycle
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An instruction is fetched from primary
storage by the Control Unit
The Control Unit decodes the instruction
The ALU receives the data and the
instruction and performs the calculation
or comparison
The result is stored in primary storage.
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The CPU (continued)
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Computer performance is measured in part
by the number of Machine Instruction Cycles
performed per second.
Factors affecting this performance include:
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Clock Speed
Word Length
Bus Width
Line Width
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The CPU (continued)
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Microprocessors evolved rapidly due
to
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Miniaturation of transistors
Decreasing distance between transistors
on the chip (decreasing line width)
Improved conductivity (flow) of electricity
Improved instruction sets programmed
into the chip.
Smaller, faster, cheaper, more
powerful chips with each generation.
10
Computer Memory
The CPU
Input
Devices
Control
ALU
Unit
Registers
Primary
Storage
Output
Devices
Communication
Devices
Secondary
Storage
11
Computer Memory Basics
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Computers are digital, and represent data in
bit patterns
Bit is shorthand for Binary digIT. The binary
system consists of two values: 0 & 1
8 bits = byte
Bytes are the basic measure of storage in
computers
ASCII Code assigns a unique character to
each pattern of 0s &1s in a byte.
Kilobytes, Megabytes, Gigabytes, Terabytes
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Primary Storage (Main
Memory)
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Main memory is a temporary storage
area that holds three things…
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information you are working with
the application software you are using
the operating system software
Increasing memory capacity increases
the performance of the system
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Primary Storage (Main
Memory)
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Types of Primary Storage
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Registers – part of the CPU; very fast; very limited
capacity
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Random Access Memory (RAM) – memory chips
on motherboard; general storage of program instructions
and data; volatile
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Cache Memory – faster than RAM; used to provide
intermediate storage between secondary storage and
RAM
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Read-only Memory (ROM) – chips storing
permanent instructions needed by computer; non-volatile
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Secondary Storage
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Non-volatile storage of data and
instructions
Huge storage capacity
Cheaper than Primary Storage
Slower than Primary Storage
Magnetic and optical storage media
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Secondary Storage Types
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Magnetic tape
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Cheap, slow, sequential access: good for backup
Magnetic Disk
 Floppy
 Hard disk
 Zip drive
Memory Cards and Cartridges
Optical
 CD-ROM, CD-RW
 DVD
 FMD-ROM
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Storage for the Enterprise
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Enterprise Storage Systems – provide
coordinated, secure, managed storage for
all enterprise data.
 Redundant array of independent disks
(RAID)
 Storage area network
 Network-attached storage
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Storage Service Providers – third party
storage utilities
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Computer Classifications
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Computers are commonly classified by their
processing power:
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Supercomputers
Mainframes
Midrange
Workstations
Microcomputers
Computing appliances
Classification boundaries are blurred.
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Computer Classifications
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Input Technology
The CPU
Input
Devices
Control
ALU
Unit
Registers
Primary
Storage
Output
Devices
Communication
Devices
Secondary
Storage
20
Input Technologies
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Human-oriented
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Keyboard
Mice / trackball
Touch screens
Stylus
Joystick
Microphone
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Automated
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ATMs
POSs
Optical Scanners
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OMR
MICR
OCR
Voice recognition
Sensors
Cameras
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Output Technology
The CPU
Input
Devices
Control
ALU
Unit
Registers
Primary
Storage
Output
Devices
Communication
Devices
Secondary
Storage
22
Output Technologies
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Monitors
Printers
Voice
Multimedia
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Strategic Hardware Issues
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Productivity
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Changing Work Styles
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Will new work styles will benefit employees and the firm as
a whole?
New Products and Services
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Will employees’ personal productivity increase as
microprocessor power and speed increases?
Is the organization ready and able to take advantage of
the new products and services that hardware advances
may make possible for the business?
Improved Communication

Is the organization ready to use multimedia for knowledge
sharing?
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Lecture Summary
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Basic role and function of the CPU
Primary and secondary storage
Classifications of computers based on
processing power
Variety and purpose of input devices
Variety and purpose of output devices
Consideration of strategic issues raised by
the advances in hardware technology
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