Cabrillo College
CIS 172 Survey of
Operating Systems
Chapter
1
Introduction to Operating Systems
An Overview of Microcomputers
What’s Contained in and Attached to a
Microcomputer?
Purpose, Types, and Functions of Microcomputer
Operating Systems
Yesterday’s Operating Systems
Desktop OSs Available Today
Learning Objectives
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Describe the microcomputers in use today
Identify common computer hardware components
Describe the purpose and functions of
microcomputer operating systems
Describe major events in the evolution of
microcomputer operating systems
List and compare the common microcomputer
operating systems
An Overview of Microcomputers
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What is a Microcomputer?
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A computer built around a microprocessor
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Microprocessor performs calculations or processing
A personal computer (PC) is a microcomputer
that complies with hardware standards set and
supported by Microsoft and Intel
An Overview of Microcomputers
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What Types of Microcomputers Are Used
Today?
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Desktops and laptops
Servers – provide services to other computers
Handheld devices – designed for a specific
purpose
What’s Contained in and
Attached to a Microcomputer?
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Microprocessor
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Also known as the CPU or processor
Central component of a microcomputer
Performs calculations
One or more per microcomputer
What’s Contained in and
Attached to a Microcomputer?
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Microprocessor (continued)
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Since the 386DX, Intel Microprocessors support
three modes:
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Real mode
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286 protected mode
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386 protected mode
What’s Contained in and
Attached to a Microcomputer?
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Microprocessor (continued)
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Real mode
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Intel processors power up in this mode
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Total address space = 1MB
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640KB limit for OS and application
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Single-tasking
What’s Contained in and
Attached to a Microcomputer?

Microprocessor (continued)
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286 protected mode
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Total address space = 16 MB
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Can multitask certain applications
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Does not support virtual machines
What’s Contained in and
Attached to a Microcomputer?
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Microprocessor (continued)
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386 protected mode
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Total address space = 4GB
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Supports the use of virtual machines
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Multitasking
What’s Contained in and
Attached to a Microcomputer?
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Microprocessor (continued)
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Processors can work with 8-bit, 16-bit, 32-bit,
and 64-bit chunks of data
The number of bits (binary digits) is the size
of data that can be processed at one time
What’s Contained in and
Attached to a Microcomputer?
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Motherboard and Chipset
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Motherboard – central circuit board
Contains one or more CPU slots or sockets into
which the processor is plugged
Chipset, memory slots, voltage regulator module
(VRM), ROM BIOS, and the expansion bus slots
are components of a motherboard
Chipset controls the flow of signals to and from
the processor and other components
What’s Contained in and
Attached to a Microcomputer?
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Memory
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Chips that store programs and data
Random-access memory (RAM)
Read-only memory (ROM)
What’s Contained in and
Attached to a Microcomputer?
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Memory (continued)
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RAM
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System, main, or physical memory
Used by active programs
One or more circuit cards with memory chips
Volatile – all is lost when the computer is powered
off
What’s Contained in and
Attached to a Microcomputer?
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Memory (continued)
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ROM BIOS
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Stores programs permanently
Called ‘firmware’ since it is non-volatile
ROM BIOS contains:
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Code for starting the computer
Code for controlling communications between
the processor and other components
A setup program for configuring system options
Configuration information stored in a special kind
of non-volatile RAM called the CMOS RAM
What’s Contained in and
Attached to a Microcomputer?
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ROM BIOS configuration information
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Disk drive types and capacity
Disk boot order
System memory
Connectors (ports)
Power management
Other information determined by
motherboard and ROM BIOS manufacturers
What’s Contained in and
Attached to a Microcomputer?
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Video Adapter and Display
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Video adapter – circuitry that sends the controlling
output signals to the display screen
Display screen – a monitor or a flat panel display
(FPD) for visual output from the computer
What’s Contained in and
Attached to a Microcomputer?
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Keyboard
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An input device with a typewriter style layout
of alphanumeric and punctuation keys
Includes additional function, control, arrow,
and editing keys
What’s Contained in and
Attached to a Microcomputer?
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Pointing Device
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Required to move a graphical pointer (cursor)
around in a GUI
Mouse is the most common pointing device –
connects via a physical cable or a wireless
connection.
Other pointing devices: touch pad, track ball,
joystick, and light pen
What’s Contained in and
Attached to a Microcomputer?
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Disk Drives
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Store data and programs
Encoded on surface of small spinning platters
Magnetic or optical technology
Floppy drives and hard disk drives use magnetic
technology
Compact disk (CD) and digital versatile disk
(DVD) drives use optical technologies
What’s Contained in and
Attached to a Microcomputer?
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Peripheral Devices
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Broad term for nonessential add-on devices
Includes printers, scanners, pointing devices,
digital cameras, external modems, and disk
drives
Purpose, Types, and Functions
of Microcomputer Operating Systems
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What is an Operating System?
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An Operating System is:
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The central control program for a computer
The intermediary between applications &
hardware
Purpose, Types, and Functions
of Microcomputer Operating Systems
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Operating System Functions
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User interface
Job management
Task management
Memory Management
File management
Device management
Security
Purpose, Types, and Functions
of Microcomputer Operating Systems
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User Interface
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AKA the ‘shell’
A software layer for user interaction
Includes the command processor
Includes the visual components of the OS
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Character-based command line
GUI
Purpose, Types, and Functions
of Microcomputer Operating Systems
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Job management
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Controls the order and time in which
programs are run
Task management
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Found in multitasking operating systems
Controls the focus
Allows user to switch between tasks
Purpose, Types, and Functions
of Microcomputer Operating Systems
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Memory Management
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Manages placement of programs and data
in memory
Virtual memory manager moves code and
data to virtual memory (file on hard drive)
Purpose, Types, and Functions
of Microcomputer Operating Systems
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File Management
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AKA data management
Allows the OS to read, write, and modify data
Data is organized into files
Allows users to organize their files into
containers called folders or directories
Purpose, Types, and Functions
of Microcomputer Operating Systems
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Device Management
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Controls hardware through device drivers
A device driver is unique to a device
Created by the manufacturer of the device to
work with a specific operating system
Purpose, Types, and Functions
of Microcomputer Operating Systems
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Security
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Provides password-protected authentication
of the user before allowing access
Checks user name and password
Restricts the actions that can be performed on
a computer, customized for each user
Purpose, Types, and Functions
of Microcomputer Operating Systems
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Categories of Operating Systems
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Single-User/Single-tasking
Single-User/Multitasking
Multi-User/Multitasking
Real-Time
Yesterday’s Operating Systems
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First the machines…
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Charles Babbage designed the first computer in
the 1820s
Apple II was the first microcomputer to combine
critical elements like keyboard, monitor, operating
system, and desirable and useful applications
Yesterday’s Operating Systems
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Then the Operating Systems
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Early single-purpose computers included
system functions
OSs did not exist as separate entity
OSs evolved from need for multipurpose
computers
Yesterday’s Operating Systems
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DOS, CP/M, Apple, and the Killer App
– To be widely accepted a computer needed a
‘killer app’
– VisiCalc was the killer app of 1970’s microcomputers
– VisiCalc ran under the CP/M OS
– VisiCalc contributed to the success of the
Apple II
– Both PC DOS and a version of CP/M were
available for the IBM PC
Yesterday’s Operating Systems
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The Second Wave (second killer app)
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Lotus 1-2-3 – a DOS spreadsheet application
that is fast and provides added functionalities
Lotus 1-2-3 became the killer app for the
IBM-PC/PC DOS combination.
Yesterday’s Operating Systems
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OS/2 (Operating System/2)
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Version 1.0 introduced in 1987
Developed by Microsoft and IBM
1.0 had costly memory and disk requirements
IBM introduced OS/2 Warp in 1990’s
IBM has ended development of new versions
Yesterday’s Operating Systems
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Microsoft Windows
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1985 first version – GUI on top of DOS
Windows 3.0, introduced in 1990, provided better
support for legacy DOS applications
Windows 3.x works in real mode, standard mode,
and 386 enhanced mode
1992 Windows 3.1 successful with MS Office
Yesterday’s Operating Systems
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Windows for Workgroups
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DOS and earlier versions of Windows had no
networking
Windows for Workgroups 3.1 and 3.11 enabled
peer-to-peer networking
Desktop OSs Available Today
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DOS from Microsoft
Windows NT
Windows 98
Windows ME
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Windows 2000
Windows XP
Macintosh OSs
UNIX
Linux
Desktop OSs Available Today
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DOS from Microsoft
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DOS provides support for interaction with
disk drives
Microsoft’s first version of DOS, called PC
DOS
Introduced with the first IBM-PC in 1981
Each major version of DOS supported new
disk capacities
DOS has a text-mode command line interface
Desktop OSs Available Today
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Windows NT
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First Microsoft OS to take full advantage of the
capabilities of the Intel’s 386 protected mode
Two main versions of NT – one for servers and
another for desktop computers
Windows NT 4.0, introduced in 1996, has a GUI
similar to Windows 95
Desktop OSs Available Today
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Windows 98
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An evolutionary development compared to
the earlier Windows operating system in
terms of GUI and integrated components
New options for customizing the GUI,
including tighter integration with Microsoft’s
Web browser, Internet Explorer (IE)
Desktop OSs Available Today
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Windows 98 (continued)
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Comes with drivers and support for devices
like DVD drives
It was the choice for PCs with plug and play
(PnP) hardware, not supported by Windows NT
Desktop OSs Available Today
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Windows Me
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Introduced in 2000 as an upgrade to Windows 98
Improved music, video, and home networking
support
Provides utilities as well as applications for
dealing with PC software configuration, digital
music, and video
Desktop OSs Available Today
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Windows 2000
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Family of OS products, introduced in 2000
Combines the best of Windows 98 and
Windows NT
Windows 2000 Professional, Windows 2000
Server, Windows 2000 Advanced Server, and
Windows 2000 Enterprise Edition
Desktop OSs Available Today
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Windows XP
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Several products, but no server version
Most common are Windows XP Home Edition
and Windows XP Professional
Improved GUI as well as several network- and
security-related features
Default desktop only contains the Recycle Bin
Windows Vista
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http://en.wikipedia.org/wiki/Windows_Vista
What is a Wiki?
Can we trust it?
Desktop OSs Available Today
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Macintosh Operating Systems
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Only run on Apple Macintosh computers
Mac OS 9 and Mac OS X common today
Desktop OSs Available Today
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Macintosh Operating Systems (continued)
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Macintosh hardware and software are proprietary
products of Apple Computer Company
Macintosh computers generally use the PowerPC
chip with an architecture that is enhanced for
graphics and multimedia
Desktop OSs Available Today
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UNIX
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Introduced by Bell Labs Computing Science
Research Center (Bell Labs) as UNIX Version 6
in 1975
A portable operating system for mini-computers
and mainframe computers
Supports timesharing and multi-user systems
An excellent server operating system as it utilizes
resources carefully, allowing only the required
services to be loaded
Desktop OSs Available Today
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UNIX (continued)
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The current commercial versions of UNIX
include Sun Microsystems’ Solaris, HewlettPackard’s HP-UX, IBM’s AIX, and Compaq’s
Tru64 UNIX
Many open source versions of UNIX are also
available, which can be changed according to
requirements
Desktop OSs Available Today
Linux
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Modeled on UNIX
Named for original developer, Linus Benedict
Torvalds
Begun in 1991 by Torvalds and others as opensource for modern computers.
Written in the C language using GNU C Compiler
(GCC)
Desktop OSs Available Today
Linux (continued)
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Distributed free
Vendors sell bundles with extras (utilities,
GUIs, manuals)
Novell, Red Hat, and others distribute such
bundles
Fastest-growing computer server OS
Making inroads on desktop computers
Chapter Summary
Microcomputers Today
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A computer consists of hardware, applications
software, and operating system software
The operating system allows the user to interact
with the computer hardware
Chapter Summary
Common Microcomputer Hardware
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The basic components of a microcomputer are
processor, motherboard, memory, video adapter
and display, keyboard, pointing device, disk
drives, and peripheral devices
You can identify hardware components by a
visual inspection, by observing information
displayed during the boot up process, and by
accessing a ROM BIOS setup program
Chapter Summary
Purpose and Functions of Microcomputer
Operating systems
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Certain functions are provided by most, if not
all, current operating systems. These functions
include a user interface, job management, task
management, memory management, file management, device management, and security.
The operating system makes everything work
together
Chapter Summary
Purpose and Functions of Microcomputer
Operating systems
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You can identify most of the functions provided
by your operating system by careful observation.
For instance, evidence of support of the security
function includes a required logon procedure
when you start your computer, and the need for
authorization to access resources on your local
computer.
Chapter Summary
Purpose and Functions of Microcomputer
Operating systems
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There are four categories of operating systems:
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Single-User/single-tasking
Single-User/multitasking
Multi-User/multitasking
Real-Time
A Single-User/single-tasking operating system
is one that allows only a single user to perform a
single task at a time
Chapter Summary
Purpose and Functions of Microcomputer
Operating systems
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An operating system that allows a single user to
perform two or more functions at once is a SingleUser/multitasking operating system
A Multi-User/multitasking operating system is
an operating system that allows multiple users to
run programs simultaneously on a single network
server, called a terminal server
Chapter Summary
Purpose and Functions of Microcomputer
Operating systems
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Real-time operating systems are defined by
their speed and ability to work with special
real-time applications programs. A Real-time
operating system is a very fast, relatively small
OS that is often embedded, meaning it is built
into the circuitry of a device and not normally
loaded from a disk drive
Chapter Summary
Major Events in the Evolution of
Microcomputer Operating Systems
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The history of current microcomputers and their
OSs involved many technical advances and the
imagination of a multitude of innovative people
You can find many accounts of the history of
computers and operating systems by searching
the Internet
Chapter Summary
What OSs Are Available Today?
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The microcomputer operating systems common
today include MS-DOS, several versions of
Windows (Windows 98, Windows 2000, and
Windows XP), Mac OS 9, Mac OS X, and several
versions of UNIX and Linux
Each of today’s common operating systems is
best suited for certain uses
Chapter Summary
What OSs Are Available Today?
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Microsoft desktop OSs are common in the
business environment
Both UNIX and Linux can be found on highend servers and on desktop computers. The use
of Linux is growing on all types of systems
The Mac OSs are commonly used in education
and in graphic workstations