Operating Systems
Module G11c
Contents
What is an "OPERATING SYSTEM"?
A group of programs
What for?
- To supervise overall computer operation
- Give basic services to all programs
Like what?
- Microsoft® Windows® (3, 3.1, 95, 98, NT, ME, 2000, XP, ...)
- Macintosh® OS (1,2,3,4,5,6,7,8,9,X)
- Linux® (Redhat®, SuSE®, Debian®...)
- Unix (AT&T®, Berkeley, SunOS®, HP®...)
- PalmOS®
- BeOS®
- ...and many others, older and newer, for larger and smaller computers.
Operating Systems vs. Application programs
Application programs do what the computer was bought for, such as:
- Word processing
- Calculations
- Accounting
- Data management
- Games
- Research
- Engineering
- Design
- Device control
- Education ...
- Operating system makes it practical!
To help understand:
organizations ~ computers
HUMAN ORGANIZATIONS
have people who... |
COMPUTERS
have programs which... |
| Do what the organization is for |
Do what the computer was gotten for
= APPLICATION PROGRAMS |
| Support the active "doers" |
Support the active programs
= OPERATING SYSTEM |
Before Operating Systems (OS):
Only one program in computer at a time
- All input and output handled by individual programs
- All errors handled by individual programs
- Result: All programming concentrated on basic details, so...
- Developing programs was slow
- Programs tended to be limited in what they could do
- Programs didn't work together: copy-and-paste between programs was impossible, sharing settings and information was impractical
Operating systems, introduced in 1964
- Programming: could become more sophisticated
- Standard storage on disk and tape
- Directories to keep track of files for you
- More than one program running at the same time
- More than one person using it at one time
- OS provides security, privacy
and much more (see Module G12c)
Some Operating Systems
Operating systems and processors
- Some are bound to one processor (CPU) family
- Microsoft® Windows® requires Intel-compatible processors for the main versions
- PalmOS® workson Palm Pilot hand-held computers
- Others can be used on several types of computer
- Linux® is designed to operate on a wide variety of processors
Features and Fixes
- Developers are always fixing and improving programs!
- Each release has a name or number, such as 3.1
- Name or first digit is the Major Release number: usually
a significant change from the previous version
Examples: Windows 3, 95, 98, 2000, XP; Mac OS 9, OS X
- Second digit (if there is one) is a Minor Release fixing problems
or adding some useful features
Example: Windows 3.1, Mac OS 10.4
- Instead of a second digit, there may be a Service Pack (SP) number
Example: Windows 98 SP2
Service Pack = collection of new features and fixes
- Many new releases are made to fix security "holes" - to prevent malicious software from getting into computers
- Automatic updates are available in newer OSs.
- Automatic updates fix problems - especially security vulnerabilities.
- Auto-update requires connecting to the Internet and downloading software patches
- Getting a new version:
- Computers always come with an appropriate OS
(unless they're do-it-yourself kits)
- Major version upgrades on an older computer:
- Usually have to be paid for
- May require more computing power than the older machine has
On Intel-based computers ("IBM-compatibles")
- MS-DOS (or PC-DOS): the original, from Microsoft
(MS-Windows 3.1 and earlier were "add-ons" needing DOS
as a starting-point)
- Windows NT, 95, 98, 2000, ME, and XP stand on their own (DOS isn't needed
to start them up)
- Unix (originally from AT&T)
Linux (works just like Unix, originally by Linus Torvalds)
On Macintosh:
- Mac OS 1,2,3,4,5,6,7,8,9 stand-alone proprietary (owned by Apple®) systems
- MAC OS X: Based on Unix, with Macintosh proprietary add-ins
On other brands and types:
- PalmOS on Palm Pilot devices
- BeOS on many hand-held devices
- Windows CE on many hand-held devices
- and many others!
Parts of an Operating System
Start-up
- BIOS read-only memory chip
- Basic Input-Output System
- Part of the computer hardware - not part of Windows, MacOS, etc.
- Instructs computer how to read and write keyboard, memory, disks, screen, and other basic devices
- POST: Power-On Self Test, tests basic functioning of computer as it starts up
Command Interpreter
Command Interpreters interpret your input and command the computer to run an appropriate program. (Maybe it's just showing an error message!)
There are two main types currently used: Command-line and Graphical User Interface
Command-Line
- Input from the keyboard
- Output to screen (or printing device on really old machines)
- Advantage: runs on very simple devices
- Disadvantage: user has to remember the commands to type
- Example: command-line FTP on a Windows computer
Graphical User Interface (GUI)
- Users view options as icons of menus
- Key components: Windows, Images, Menus, Pointer (WIMP)
- Advantage: user need only know the general system; icons and menus provide the options
- Disadvantage: requires more powerful equipment
- Example: Icons in a window
- Example: Menus
Utilities
- Utilities are programs that help you use the computer in different ways, including filing, communicating, troubleshooting and maintaining your computer.
- Many utilities are available on all computers...see module G12c)
Audience:
This is for people who want to learn more about what an "operating
system" is, and already know a little about how computers
operate (Modules G01c, G02c,
G03c, G04c, and
G05c provide background information for
this.)
Objectives:
Upon successful completion of Module G11c, the student will
demonstrate understanding of:
Generally: The role of operating systems in modern computers,
and their major components.
Specifically:
- What an operating system is: a group of programs which provide
supervision and basic services;
- The difference between operating systems and application programs;
- The limitations of running a computer without an operating
system;
- The major services provided by operating systems: Running
and monitoring other programs, I/O, security, directory of files,
coordinating multiple programs and multiple services;
- The parts of a microcomputer operating system: startup, basic
I/O services (BIOS), command language interpreter, utilities.
About this document...
Module G11c: Operating Systems
- Author:
- Laurence J. Krieg
- Institution:
- Department
of Computer Information Systems, Washtenaw
Community College
- Dates:
- Original 29 Mar 1988
Revised 17 Mar 2006
HTML version 13 May 1996
- Copyright:
- Copyright © 1996-2006, Laurence J. Krieg, Washtenaw Community College
Instructors: You may point to this file in your Web-based materials.
Students: you may make a copy for your personal use.
All other uses: contact the author, Laurence J. Krieg,
for permission.