Download Systems Software

Systems Software / The
Operating System
CSC 101
1.0
October 14, 2010
What is Software?
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Intangible
A file
Performs tasks / jobs
A set of instruction
Run/executed by the Central
Processing Unit (CPU)
• Must be in the computer’s
memory to run
Two Types of Software
Systems Software
Applications Software
What is Systems Software
• Controls the system
– Hardware
– Software
– Input / Output (I/O)
• Middle man
• Comprised of
– Operating system (OS)
– Utility Programs
Platform
Computer processor & operating
system
Flavor
Version of an operating system
Systems Software Programs
• Mainframe computers
– Unix
• Desktop / Laptop computers
– Windows
– Mac OSX
– Linux
Unix
• Bell AT&T labs - 1969
• Runs on large computers
Windows
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Microsoft
Bill Gates
Leading market share
Windows 3.1
Windows 9
Windows 98
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Windows ME
Windows 2000
Windows NT
Windows XP
Windows Vista
Windows 7
Mac OSX
• Apple
Computers
• Steve Jobs
• Control
hardware &
software
• Based on Unix
Linux
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Linus Tovalds - 1991
Open source
Based on Unix
Free
Distros
Operating System Parts
• Kernel
– Heart of the operating system
– Must be in memory while the
computer is running
– All the important tasks the OS must
do
• User Interface
– How a human gives commands to
the OS
Types of Operating Systems
• Classify by Users
– Single User
– Multiple User
• Classify by Task
– Single Task
– Multitasking
• Real-time Systems
Operating System Jobs
• Controls the
hardware
• Controls all the other
software programs
Managing the Processor
• Controls the timing of events the processor
works on
REQUEST
Operating
System
Managing Memory
• The operating system allocates space in RAM for
instructions and data
RAM
Operating
System
Managing Peripheral Devices
• Co-ordinates system hardware
• Device drivers
– Small programs
– How to communicate with a device
• Plug and Play
– Device device drivers included with systems
software
– Makes devices immediately usable
Managing Storage
• Handles where files are
placed on a storage
device
• Retrieves files from
storage device & puts
them in memory
• Remembers file details
• File allocation table / File
allocation system
Application Software Interface
• Requests made by application programs to the
OS
– Save a document
– Print a document
– Open a document
– Send an e-mail
– Play a song
User Interface
• Enables you to interact
with the computer
• Types of interfaces:
– Command-driven
interface
– Menu-driven interface
– Graphical user interface
Utility Programs
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Additional small programs
Maybe added on later
Help with maintenance
Make the computer easier to use
– Task Scheduler
– Defrag
– Screen savers
– Install/ uninstall wizard
The Boot Process
• Step 1: The basic input/output system (BIOS)
is activated
• Step 2: A power-on self-test (POST) checks
attached hardware
• Step 3: The operating system loads into RAM
• Step 4: Configuration and customization
settings are checked