2. Fundamentals of Information
Systems, Second Edition
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Learning Objectives
– Identify and discuss the role of the essential
hardware components of a computer system.
– List and describe popular classes of computer
systems and discuss the role of each.
– Outline the role of the operating system and
discuss how operating systems have evolved
over time.
– Identify and briefly describe the functions of
the two basic kinds of software.
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Computer System Components
Math calculations
Access, decode,
coordinate
instructions
Hold program
instructions and
data
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Hardware Components in Action
• Instruction phase
– Step 1: Fetch instruction
– Step 2: Decode instruction
• Execution phase
– Step 3: Execute the instruction
– Step 4: Store the results
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Processing Characteristics and
Functions
• Machine cycle time: Time to execute the
instruction phase
• Clock speed:
– Rate at which electronic pulses are produces.
– Measured in MHz
• Wordlength
– Bit (Binary digiT): 0 or 1
– Unit for moving data
– Wordlength: The number of bits a CPU can process in
a unit time
– 32-64 bit processors
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Types of Memory (1)
• Random access memory (RAM)
– Volatile
– Extended Data Out (EDO) RAM
– Dynamic Ram (DRAM)
– Synchronous DRAM:
• Faster transfer speed between memory and
processor
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Types of Memory (2)
Read-only memory (ROM)
– Non-volatile
– Permanent data and instructions from
manufacturer
– Types
• PROM: Programmable
• EPROM: Erasable programmable
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Secondary Storage Access Methods
• Sequential access
– Access in the same order it was written
– Ex: Need to access memory location 5. Then, you
need to go through 1, 2, 3, and 4 first.
• Direct access
– Directly access the location
– Faster than sequential access
• Sequential access storage devices (SASD)
• Direct access storage devices (DASD)
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Secondary Storage Devices (1)
• Magnetic tapes: Similar to audio tapes, SASD
• Magnetic discs: Hard disk, DASD
• RAID: Redundant array of independent
inexpensive disks
– Data stored more than once in one of the disks
– Even if one disk fails, data can still be retrieved
• SAN: Storage area network
– Consist of many storage devices
• Optical discs, DASD
– CD-ROM
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Secondary Storage Devices (2)
• Magneto-optical discs
• Digital versatile discs (DVD): Up to 17 GB
storage
• Memory cards
– Installed in a slot
– Portable
• Expandable storage: Removable disk cartridges
– Portable
– Zip drives
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Input Devices
• Personal computer input devices
– Keyboard
– Mouse
• Voice-recognition devices
– Microphone
– Software to convert voice into bits
• Digital computer cameras
– Record images and video
• Terminals
– Connects to a powerful server for computations
• Scanning devices
– Page
– Handheld
• Touch-sensitive Screens
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Overview of Software
• Computer programs: Sequences of instructions
• Documentation: Describe program functions
• Systems software: Coordinate the activities of
the hardware
• Computer system platform:
– Hardware configuration + systems software
• Application software: Programs that help users
with certain tasks
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Operating Systems
• Perform common computer hardware functions
– Ex: Get input from keyboard
• Provide a user interface
– Command-based user interface (ms-dos)
– Graphical-user interface (windows)
• Provide a degree of hardware independence
– Application program interface
• Manage system memory
– Convert logical view to physical view
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Operating Systems
• Manage processing tasks
– Allocate computer resources
– Multitasking (run more than once application at a
time)
– Time-sharing (allow multiple access to a system)
• Provide networking capability
– Enable connection to the Internet
• Control access to system resources
– Authentication
• Manage files
– Access to files
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Workgroup Operating Systems
• Windows 2000 Server
• Unix
• Netware
• Red Hat Linux
• Mac OS X Server
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Consumer Appliance Operating Systems
• Windows CE .NET
• Windows XP Embedded
• Handheld PC
• Pocket PC
• Palm OS
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Summary of Programming Languages
• First: Computer interactions written in machine code
– Machine language
• Second:
– Abbreviations for common operations
– Assembler converts code to machine language
– Assembly language
• Third
– Instructions are English-like
– Compliers convert code to machine language
– Fortran: Good for scientific computing
– Cobol: Good file handling
– Java: Good for Web applications
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Summary of Programming Languages
• Fourth
– Even easy for non-programmers
– Tell what to do, not how to do it
– Focus, Powerhouse
• Visual Programming Languages
– Point-and-click
– Drag-and-drop
– Useful for user interfaces
– Visual Basic, Visual C++
• Object-oriented Languages
– Objects contain data, methods to operate data
– C++, Java
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Summary
• Hardware devices work together to perform input, processing, data
storage, and output.
• There are two main categories of software: systems software and
application software.
• An operating system (OS) is a set of computer programs that
controls the computer hardware to support users’ computing needs.
• Application software may be proprietary or off-the-shelf.
• There are five generations of programming languages, plus object-
oriented programming languages.
