Management information system ralp 7e ch03

Principles of Information Systems, Seventh Edition 4Computer Systems: Integrating the Power of Technology • Computer system • Special subsystem of an organization’s overall information

Principles of Information Systems, Seventh Edition 2

• Assembling an effective, efficient computer system requires an

understanding of its relationship to the information system and the organization The computer system objectives are subordinate to, but supportive of, the information system and the needs of the

organization

• Describe how to select and organize computer system components

to support information system (IS) objectives and business

organization needs

• When selecting computer devices, you also must consider the

current and future needs of the information system and the

organization Your choice of a particular computer system

device should always allow for later improvements

• Describe the power, speed, and capacity of central processing and

Principles of Information Systems, Seventh Edition 4

Computer Systems: Integrating the

Power of Technology

• Computer system

• Special subsystem of an organization’s overall information

system

• Integrated assembly of devices used to input, process,

store, and output data and information

• Hardware

• Any machinery—most of which use digital circuits—that

assists in the input, processing, storage, and output

activities of an information system

Hardware Components

• Central processing unit (CPU)

• Input devices

• Output devices

Principles of Information Systems, Seventh Edition 6

Hardware Components (continued)

• Communications devices

• Primary storage devices

• Secondary storage devices

Figure 3.1: Computer System

Components

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Hardware Components in Action

• Step 1: Fetch instruction

• Step 2: Decode instruction

• Step 3: Execute instruction

• Step 4: Store results

Figure 3.2: Execution of an Instruction

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Processing and Memory Devices:

Power, Speed, and Capacity

• System unit: houses the components responsible for processing—

the CPU and memory

• All other computer system devices are linked either directly or

indirectly into the system unit housing

Processing Characteristics and

Functions

• Machine cycle time is measured in:

• Microseconds (1 millionth of a second)

• Nanoseconds (1 billionth of a second)

• Picoseconds (1 trillionth of a second)

• MIPS (Millions of Instructions Per Second)

Principles of Information Systems, Seventh Edition 12

Processing Characteristics and

Functions (continued)

• Clock speed: electronic pulses that affect machine cycle time

• Hertz (Hz): one cycle (pulse) per second

• Megahertz (MHz): millions of cycles per second

• Microcode: elementary circuits and logical operations a processor

performs when executing instructions

Figure 3.3: Clock Speed and the

Execution of Microcode Instructions

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Wordlength and Bus Line Width

• Bit: a binary digit (0 or 1)

• Wordlength: number of bits the CPU can process at any one time

• Bus line: physical wiring that connects the computer system

components

Physical Characteristics of the CPU

• CPU: collection of digital circuits

• Electrical current flows through silicon

• Moore’s Law: transistor densities on a chip double every 18 months

• Superconductivity: property of certain metals that allows current to

flow with minimal electrical resistance

• Optical processors: computer chips that use light waves instead of

electrical current to represent bits

Principles of Information Systems, Seventh Edition 16

Figure 3.4: Moore’s Law

Complex and Reduced Instruction Set

Computing

• Complex instruction set computing (CISC): chip design that

places as many microcode instructions into the central processor as possible

• Reduced instruction set computing (RISC): chip

design that involves reducing the number of microcode instructions built into a chip to an essential set of common microcode

instructions

Principles of Information Systems, Seventh Edition 18

Memory Characteristics and Functions:

Storage Capacity

Types of Memory

• Random access memory (RAM): temporary and volatile

• Types of RAM

• EDO (Extended Data Out)

• DRAM (Dynamic RAM)

• SDRAM (Synchronous DRAM)

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Types of Memory (continued)

• ROM (read-only memory): usually nonvolatile

• Types of ROM

• PROM (programmable read-only memory)

• EPROM (erasable programmable read-only memory)

• Cache memory

• High-speed memory that a processor can access more

rapidly than main memory

Figure 3.5: Basic Types of Memory Chips

Principles of Information Systems, Seventh Edition 22

Figure 3.6: Cache Memory

• Multiprocessing: the simultaneous execution of two or more

instructions at the same time

• Massively parallel processing

• Speeds processing by linking hundreds or thousands of

processors to operate at the same time, or in parallel

• Can coordinate large amounts of data and access them

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Figure 3.7: Massively Parallel Processing

Secondary Storage

• Secondary storage: offers advantages of nonvolatility, greater

capacity, and greater economy

• Access methods, storage capacities, and portability required are

determined by the information system’s objectives

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Table 3.1: Cost Comparison for Various

Forms of Data Storage

Access Methods

• Sequential access: retrieval method in which data must be retrieved

in order; devices used are called sequential access storage devices (SASDs)

• Direct access: retrieval method in which data can be retrieved in

any order; devices used are called direct access storage devices

(DASDs)

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Secondary Storage Devices

• Magnetic tapes

• Magnetic disks

• Virtual tape

• Optical discs

Secondary Storage Devices

(continued)

• Digital versatile disk (DVD)

• Magneto-optical (MO) disks

• Memory cards

• Flash memory

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Enterprise Storage Options

• Attached storage

• Network-attached storage (NAS)

• Storage area network (SAN)

Figure 3.12: Storage Area Network

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Input and Output Devices: The Gateway to Computer Systems

• Through input and output devices, people provide data and

instructions to computer and receive results from it

• Selection of input and output devices depends on organizational

goals and information systems objectives

Characteristics and Functionality

• Data: can be human- or machine-readable

• Data entry: process of converting human-readable data into

Principles of Information Systems, Seventh Edition 34

Input Devices (continued)

• Scanning devices

• Optical data readers

• Magnetic ink character recognition (MICR) devices

• Point-of-sale (POS) devices

• Automated teller machine (ATM) devices

Principles of Information Systems, Seventh Edition 36

Input Devices (continued)

• Pen input devices

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Output Devices (continued)

• Organic light-emitting diodes (OLEDs)

• Printers and plotters

• Computer output microfilm (COM) devices

• Music devices

Computer System Types, Selecting,

and Upgrading

• Computers can be classified as either special purpose or general

purpose

• Special-purpose computers: used for limited applications by

military and scientific research groups

• General-purpose computers: used for a wide variety of

applications

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Computer System Types

• Handheld computers

• Portable computers

• Thin client

• Desktop computers

Computer System Types (continued)

• Workstations

• Servers

• Mainframe computers

• Supercomputers

Principles of Information Systems, Seventh Edition 42

Selecting and Upgrading Computer

Systems

• Hard drive considerations

• Main memory considerations

• Printer considerations

• DVD burners

• Hardware: machinery that assists in the input, processing, storage,

and output activities of an information system

• Hardware components include central processing unit (CPU), input

and output devices, communications devices, primary storage

devices, and secondary

storage devices

• Random access memory (RAM): temporary and volatile

• Read-only memory (ROM): usually nonvolatile

Principles of Information Systems, Seventh Edition 44

Summary (continued)

• Multiprocessing: simultaneous execution of two or more

instructions at the same time

• Sequential access: records must be retrieved in order

• Direct access: records can be retrieved in any order

• Examples of secondary storage devices: magnetic tapes and disks,

optical disks, and DVDs

• Enterprise storage options: attached storage, network-attached

storage (NAS), and storage area network (SAN)

Summary (continued)

• Examples of input devices: keyboards, mice, voice-recognition

devices, terminals, scanning devices, and touch-sensitive screens

• Examples of output devices: display monitors, liquid crystal

displays (LCDs), printers, and plotters

• Computers can be classified as either special purpose or general

purpose

• Computer system types: handheld computers, portable computers,

desktop computers, workstations, servers, etc