Download IOS101

Week 2 -- Introduction to Operating Systems
Agenda
 Open Source and Closed Source OSs
 Windows family of Operating Systems
 Types of Operating Systems
 Functions of an Operating System
Open and Closed Source OSs
 Open Source – binaries + source code
 Linux, OpenBSD, FreeBSD
 Closed source – binaries only
 Windows, Adobe, IBM, Sun
5/23/2017
3
Windows Family of OSs
 MS-DOS
 Windows 9x (95/98/Me)
 NT\2000\XP\Vista
 Windows CE (Pocket PC)
Microsoft Family of OS’s
& Win32 API
Win 32 API
NT\2000\XP\Vista
Windows 95\98\Me
Windows CE
Current Desktop Usage
Usage Share of Desktop Operating Systems from Wikipedia - Dec. 2008
http://en.wikipedia.org/wiki/Usage_share_of_desktop_operating_systems
Feature Summary
Feature
Windows 9x
NT\2000\XP\Vista
Hardware Requirements
Low, 486 PC with 16MB of
RAM
High, Pentium 800Mhz with
512 MB of RAM
Hardware Compatibility
Supports Legacy devices
Supports most current
devices but is not backward
compatible
Software Compatibility
Full backward compatibility
No support for applications
what require direct access to
hardware
Performance
Runs best on older machines
Runs best on new machines
with high bus speed and lots
of RAM
Reliability
Sometimes not stable
Very stable because all
applications run in protected
memory space
Security
Low to nil security
Very high security down to
the file level
Types of Operating Systems
 Single-User, Single Process
 Single-User, Multi-process
 Multi-user, Multi-process
 Real-Time Operating Systems
Single-User Single Process
 Allows one user at a time
 Allows one process at a time
 E.g. DOS, MacOS, Win3.1
Single-User Multi-process
 Allows one user at a time
 Allows multiple processes to run simultaneously
 E.g. OS/2, Win95/98, WinNT workstation
Multi-user Multi-process
 Allows multiple users simultaneously
 Allows every user to run multiple processes
simultaneously
 E.g. UNIX, Linux, W2K, WinXP
Real Time Operating Systems
 Used with “embedded” applications
 Operate in “real-time” to Control machinery, scientific
instruments and industrial systems
Functions of an Operating System
 The 4 main functions that an operating system
provides us with are:
1. User Interface
2. File System Management
3. Task Management
4. Device Management
User Interface
 The user interface can be command line like UNIX,
providing power and flexibility or
 GUI, like Windows providing ease of use.
 Through the User Interface the user can interact with
the other OS functions, e.g. device management
File Management
 Files are an abstract storage device resource
 Most common method of storing information on a
computer
 Files can be “distributed”
Task Management
 Administers the allocation and use of “primary”
memory
 Uses “virtual memory”
 Uses memory on remote machines
 Tasks are divided into processes
 Processes are the basic units of computation
 Resources are the computer components needed by
the process, CPU, RAM, drives, etc.
Device Management
 Most important aspect of OS
 All devices treated in a similar manner
 All devices require resources to operate
 All require “device drivers”
Operating System Functions
User
Application Program
interfaces
Operating System
Hardware
Overview of OS Functions
Application Program Layer
File Management
User Interface
(shell)
Operating System Layer
Device Management
Hardware Layer
Task Management