Transcript
Operating Systems
Course: B.Sc-CSSubject: Fundamental Of Information Technology
Unit: 3
Operating System Software• Operating System (OS) – Software that controls the overall operation of a
computer
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What is an operating system (OS)?Operating System Software
Software which manages the overall operation of the computer system including:• hardware (CPU, RAM, I/O)• security• system interface• application interface
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The functions of an operating system
1. Manages and Interacts with Computer Hardware
2. Provides and Manages System Security
3. Provides the System Interface
4. Provides the Interface for Application Software
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1. Manages and Interacts with Computer Hardware
• Manages the CPU- What software programs the
CPU works on and when
• Manages RAM- What is stored in RAM and where it is stored- Virtual memory- OS will send message when RAM is full
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1. Manages and Interacts with Computer Hardware (continued)
• Provides the interface for storage devices and manages how data is stored on those devices- in charge of formatting disks- creates sectors and clusters- creates F.A.T. or V.T.O.C.- sends message when disk is full or there is some other problem with writing data to the disk
- virtual memory - CD-ROM, DVD-ROM - Flash drive
1. Manages and Interacts with Computer Hardware (continued)
• Provides the Interface for Input and Output Devices– keyboard, mouse, printer, – device drivers = software
programs which allow the hardware device to be used by the operating system and by application software
Rick Graziani graziani@cabrillo.edu 7
2. Provides and Manages System Security
Single-user Operating Systems• minimal security• user has full authority
Server Operating Systems• login and password capability• protection of user’s data stored
on the server’s central hard disk drives
• protection and security for software programs
Rick Graziani graziani@cabrillo.edu 8
3. Provides the System Interface
System Interface or shell = the interface between the user and the computer
Command Line Interface (CLI)
• Linux, UNIX, DOS, older OS’s
Graphical User Interface (GUI)
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4. Provides the Interface for Application Software
• Operating systems are software
• Operating systems are designed and developed for a specific CPU or “family of CPUs”– Macintosh OS: Motorola 680xx,
PowerPC Gx, Intel– DOS: Intel CPUs– Windows 9x and XP: Intel
80386, 80486, and Pentium CPUs
– Linux: Intel CPUs– MS NT & 2000: Intel CPUs
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4. Provides the Interface for Application Software (continued)
• Application software is developed for an operating system
MS Word for Windows XP• Windows XP• Intel CPU
MS Word for the Macintosh• Macintosh OS X• Gx CPU or Intel CPU
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Order of Development
1. The CPU
2. Other Hardware Components
3. Operating System Software
4. Application Software12
Types of Operating System
Architecture of Computer System
Hardware
Operating System (OS)
Programming Language (e.g. PASCAL)
Application Programs (e.g. WORD, EXCEL)
Operating System
• a collection of programs which control the resources of a computer system
• written in low-level languages (i.e. machine-dependent)
• an interface between the users and the hardware
• when the computer is on, OS will first load into the main memory
OperatingSystem
Device configurationControls peripheral devices connected to the computer
File managementTransfers files between main memory and secondary storage, manages file folders, allocates the secondary storage space, and provides file protection and recovery
Memory managementAllocates the use of random access memory (RAM) to requesting processes
Interface platformAllows the computer to run other applications
Basic functions of the operating system
Other function of Operating System
• best use of the computer resources• provide a background for user’s programs to
execute• display and deal with errors when it happens• control the selection and operation of the
peripherals• act as a communication link between users• system protection
Common Operating Systems and Their Differences
• Network Operating System– UNIX / Linux / MS Windows2000 Server
• Desktop Operating System– MS Windows 9X/Me / Mac OS / DOS
• Mobile Operating System– Palm OS and Pocket PC
Different Features of Operating System
Type of Operating System
• Batch processing• Real time processing• Time sharing processing
Batch processing
• Jobs, together with input data, are fed into the system in a batch.
• The jobs are then run one after another.• No job can be started until previous job is
completed
Real time processing
• immediate response is needed.
• For example – anti-missile defense system– airplane landing control system– interrupt error in computer system
Time sharing processing
• Each user is given a time slice to interact with the CPU.
• The size of the time slice will depend on the system.
• Each user is served in sequence.
Special Features of OS
• multi-tasking• multi-programming• parallel processing• buffering• spooling
Multi-tasking
• to handle 2 or more programs at the same time from a single user ‘s perception– CPU can only perform one task at a time, however,
it runs so fast that 2 or more jobs seem to execute at the same time
Multi-programming
• 2 or more programs store in the main memory at the same time
• when one job reeds to wait (e.g. I/O operation), CPU switch to another job to execute
• when the first job finishes waiting, CPU will get back the first job to execute
Parallel Processing
• use 2 or more CPUs to handle jobs• computer networking
Job 1 Job 2
Job 3
Job 4
Job 1
Job 2
Job 3
Job 4
CPU 1 CPU 2 CPU 1
time time
without multiprocessing
with multiprocessing
Buffering
• A temporary storage area (buffers) to read data from input device or send data to the output device
• keep CPU busy– because I/O operation is slow
Reference
Book Reference1. Operating System Concepts by Abraham Silberschatz,
Peter B. Galvin, Greb Gagne2. Operating System Concepts by James Lautor
Peterson, Abrahamautor Silbeschatz3. Database System Concepts by Abraham Silberschatz,
Henry F. Korth, S.SudarshanImage Reference4. https://www.google.co.in/search?q=database+Manage
ment+system+books&hl=en-IN&biw=1517&bih=714&tbm=isch&source=lnms&sa=X&ei=9MCjVLPGIdTmuQTen4HQCQ&ved=0CAYQ_AUoAQ&dpr=0.9#hl=en-IN&tbm=isch&q=database+Management+system
5. https://www.google.co.in/search?q=database+Management+system+books&hl=en-IN&biw=1517&bih=714&tbm=isch&source=lnms&sa=X&ei=9MCjVLPGIdTmuQTen4HQCQ&ved=0CAYQ_AUoAQ&dpr=0.9#hl=en-IN&tbm=isch&q=operating+system
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