MANAGING INFORMATION TECHNOLOGY
7th EDITION
CHAPTER 2
COMPUTER SYSTEMS
-HARDWARE
-SOFTWARE
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HARDWARE
Building Blocks of Information Technology
Hardware Software Networks Data
Chapter 2 Chapter 2 Chapter 3 Chapter 4
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COMPUTER SYSTEMS
• Hardware:
Physical pieces of a computer system
• Software:
Set of programs that control the operations of a computer
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BASIC COMPONENTS OF COMPUTER SYSTEMS
• All computers made up of the
same set of six building blocks:
input, output, memory,
arithmetic/logic unit, control
unit, and files
• Control unit and
arithmetic/logical unit together
known as the central processing
unit (CPU)
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BASIC COMPONENTS OF COMPUTER SYSTEMS
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Input:
• Device(s) needed to enter
data into the computer for it
to use in computations and
comparisons
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Input: What is the difference between a terminal
and a PC?
• Terminal
- Designed strictly for input and output
- Has keyboard and screen
- Does not have a processor
- Connected to a computer with a processor via
telecommunications
- Examples: point-of-sale terminal, ATM
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Common Input Methods:
- Keyboard: input entered by user through keystrokes
- Mouse, stylus, touchpad: alternative to keystrokes
- Disk drive or flash drive: data on disk read into memory
- Magnetic ink character recognition (MICR): used to process
bank checks
- Barcode labeling: scans barcodes on packages or products, and
reads into computer
- Optical character recognition (OCR): directly scans typed,
printed, or handwritten material
- Imaging: inputs digital form of documents and photos
Keyboard
Disk Drive
Barcode
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Output:
• Device(s) needed to produce
results in a usable format
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Common Output Methods:
- Video display unit: displays output on a screen
- Disk drive or flash drive: output written to disk for storage
- Printer: output to paper (various types of printers)
- Computer output microfilm (COM): microfilm generated
for archive copies in small space
- Voice response units: computer-generated verbal response
messages
Video Display
Disk Drive
Microfilm
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Memory:
• Referred to as main memory or
primary memory
• All data flows to and from
memory
• Divide into cells
- Each has a unique address
- Can only store limited amount
of data
-Byte: stores one character of data
-Word: stores two or more
characters of data
Memory
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Memory:
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Memory:
• Each memory cell is a set of circuits
• Each circuit is on or off (represented by 1 or 0)
• Each circuit corresponds to a bit (binary digit)
• Most computers – 8 bits (circuits) represents a character (byte)
• 2 common bit coding schemes used today:
- ASCII (American Standard Code for Information
Interchange)
- EBCDIC (Extended Binary Coded Decimal Interchange
Code)
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Arithmetic/Logical Unit:
• Carries out:
- Mathematical operations
(addition, subtraction,
multiplication, division)
- Logical operations
(number comparisons)
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Arithmetic/Logical Unit:
• Consists of VLSI (Very-Large Scale Integration) circuits on a
silicon chip
• Can perform up to billions of operations per second
• Numbers are taken from memory as input and results are
stored in memory as output
ALU Circuits
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Computer files:
• File devices used to store vast
quantities of data
• Main memory is limited,
volatile and expensive
• Advantages:
- File devices or secondary memory
are used to store additional data that
is non-volatile
• Disadvantages:
- It has relatively slow speed
• Storage Devices:
- Magnetic tape drives, disk drives,
floppy drives
- Optical CD or DVD drives
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Types of Computer files:
• Sequential Access Files
- Records are stored in sequence according to file’s control
key
- Usually stored on magnetic tape
• Direct Access Files
- Records can be accessed immediately, without regard to
physical location
- Stored on Direct Access Storage Devices (DASD)
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DIRECT ACCESS STORAGE DEVICES
• Types of DASD:
• Fixed (hard) drives
• Optical disk storage
- CD-ROM - DVD-ROM
- CD-R - DVD-R
- CD-RW - DVD-RW
• Removable drives
- Floppy Drives
- Zip Drives
- Flash (keychain) Drives
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BASIC COMPONENTS OF COMPUTER SYSTEMS
Control unit:
• Controls the other five
components of the computer
system
• Used to take advantage of speed
and capacity of other
components
• List of operations, called a
program, tells the control unit
what to do
• These operations are read from
memory, interpreted, and
carried out one at a time
(stored- program concept)
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STORED-PROGRAM CONCEPT
• Computer Program
- A list of what is to be done for an application
- Each step or operation is called an instruction
• Machine Language
- Computer program written for specific computer model
- Program executed by control unit; consists of operation code and
addresses
• Measure of Computer Power
- Millions of instructions per second (MIPS)
- Millions of floating point operations per second (MFLOPS)
• Benchmarking is used to compare speed for running a set of jobs on
different machines
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TYPES OF COMPUTER SYSTEMS
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TYPES OF COMPUTER SYSTEMS
Microcomputers:
• For personal computing
• Can generally be carried or moved by one person and only
have one keyboard and display unit
• Examples:
- Desktop PC
- Laptop or notebook
- Handheld or personal digital assistant (PDA)
- Tablet PC
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TYPES OF COMPUTER SYSTEMS
Microcomputers:
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TYPES OF COMPUTER SYSTEMS
Microcomputers, continued:
• Two major microcomputer platforms
- IBM-compatible PCs (personal computers)
- Apple microcomputers (does not use Windows OS)
• Have been put to a myriad of uses
- Record-keeping
- Word processing
- Presentations
- Programming
- and a “client” in a client/server system
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TYPES OF COMPUTER SYSTEMS
Midrange systems:
• In 1980s, included 2 types of computer systems
1. Workstations
- Microcomputers with more powerful chips than PCs
- Reduced instruction set computing (RISC) chip yielded
greater performance because it was specialized
2. Minicomputers
- Less powerful and less expensive than mainframe systems
- Used for departmental computers & office automation
Midrange Systems
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TYPES OF COMPUTER SYSTEMS
Midrange systems - today:
• Servers for client/server applications, Web server, etc.
- Low-end
- Essentially high-powered PCs
- Typically built on Intel Pentium, Celeron, Xeon or AMD
processors
- Often run Windows Server software
- High-end
- Powered by RISC processors or top-of-the-line Intel or
AMD processors
- Usually run Linux or some variation of UNIX
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TYPES OF COMPUTER SYSTEMS
Mainframe Computers:
• Computer platforms for most major corporations and
government agencies
• Major strength is versatility in application processing
- Online and batch processing
- Integrated enterprise systems
- Engineering and scientific applications
- Network control
- Systems development environment (not production)
- Web server
• Major players today: IBM, Fujitsu, Unisys
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TYPES OF COMPUTER SYSTEMS
Supercomputers:
• “Number-crunchers” at 250K MFLOPS (millions of floating
point operations per second)
• Handle problems generated by research scientists
• High-end supercomputers located in government, R&D labs,
major universities
• Cost: $1 - $100 million
• One of fastest supercomputers (IBM Blue Gene/P):
294,912 processors and can achieve speed of 1 petaflop
(One thousand million million (10^15) floating-point operation
per second)
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