ch3 - Operating System Structure.pdf - Chapter 3 Operating System Structure 1 BIC20803 Operating Systems Chapter 3 Chapter 3 Operating-System Structures

ch3 - Operating System Structure.pdf - Chapter 3 Operating...

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Operating System Structure Chapter 3 BIC20803 Operating Systems: Chapter 3 1
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Chapter 3: Operating-System Structures Operating System Services User Operating System Interface System Calls Types of System Calls System Programs Operating System Design & Implementation Operating System Structure Virtual Machines System Boot BIC20803 Operating Systems: Chapter 3 2
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Program What a program is? A set of computer code a specific set of ordered operations for a computer to perform. BIC20803 Operating Systems: Chapter 3 3
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A view of operating system services BIC20803 Operating Systems: Chapter 3 4
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BIC20803 Operating Systems: Chapter 3 5
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Operating System Services One set of operating-system services provides functions that are helpful to the user: 1. User interface - Almost all operating systems have a user interface (UI) Varies between Command-Line (CLI), Graphics User Interface (GUI) BIC20803 Operating Systems: Chapter 3 6
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1. Program execution - The system must be able to load a program into memory and to run that program, end execution, either normally or abnormally (indicating error) 2. I/O operations - A running program may require I/O, which may involve a file or an I/O device. Since user programs cannot execute I/O operations directly, the OS must provide some means to perform I/O. 3. File-system manipulation - The file system is of particular interest. Obviously, programs need to read and write files and directories, create and delete them, search them, list file Information, permission management. BIC20803 Operating Systems: Chapter 3 7
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Operating System Services (Cont.) One set of operating-system services provides functions that are helpful to the user (Cont): 4. Communications Processes may exchange information, on the same computer or between computers over a network Communications may be via shared memory or through message passing (packets moved by the OS) BIC20803 Operating Systems: Chapter 3 8
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5. Error detection OS needs to be constantly aware of possible errors May occur in the CPU and memory hardware, in I/O devices, in user program For each type of error, OS should take the appropriate action to ensure correct and consistent computing. Example of action: halt the system BIC20803 Operating Systems: Chapter 3 9
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Operating System Services (Cont.) Another set of OS functions exists not for helping the user, but rather for ensuring the efficient operation of the system itself via resource sharing . 6. Resource allocation - When multiple users or multiple jobs running concurrently, resources must be allocated to each of them Many types of resources - Some (such as CPU cycles, main memory, and file storage) may have special allocation code, others (such as I/O devices) may have general request and release code. 7. Accounting - To keep track of which users use how much and what kinds of computer resources (see Resource Monitor) 8. Protection and security -
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