Principles of Information Systems, Seventh Edition2 Assembling an effective, efficient computer...

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 memory devices

• Describe the access methods, capacity, and portability of secondary storage devices

• Discuss the speed, functionality, and importance of input and output devices

• Identify popular classes of computer systems and discuss the role of each


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


Hardware Components (continued)

• Communications devices

• Primary storage devices

• Secondary storage devices


Figure 3.1: Computer System Components


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


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)


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


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


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


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)


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


Figure 3.6: Cache Memory


Multiprocessing

• 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 with greater speed


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


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)


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

• Expandable storage


Enterprise Storage Options

• Attached storage

• Network-attached storage (NAS)

• Storage area network (SAN)


Figure 3.12: Storage Area Network


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 machine-readable form

• Data input: involves transferring machine-readable data into the system

• Source data automation: involves capturing and editing data where the data is initially created and in a form that can be directly input to a computer


Input Devices

• Personal computer input devices

• Keyboard

• Mouse

• Voice-recognition devices

• Digital computer cameras

• Terminals


Input Devices (continued)

• Scanning devices

• Optical data readers

• Magnetic ink character recognition (MICR) devices

• Point-of-sale (POS) devices

• Automated teller machine (ATM) devices


Input Devices (continued)

• Pen input devices

• Light pens

• Touch-sensitive screens

• Bar-code scanners

• Radio-frequency identification (RFID)


Output Devices

• Display monitors

• Liquid crystal displays (LCDs)

• Active-matrix

• Passive-matrix


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


Computer System Types

• Handheld computers

• Portable computers

• Thin client

• Desktop computers


Computer System Types (continued)

• Workstations

• Servers

• Mainframe computers

• Supercomputers


Selecting and Upgrading Computer Systems

• Hard drive considerations

• Main memory considerations

• Printer considerations

• DVD burners


Summary

• 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


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.

Principles of Information Systems, Seventh Edition2 Assembling an effective, efficient computer...

Documents

Transcript of Principles of Information Systems, Seventh Edition2 Assembling an effective, efficient computer...