Post on 05-Jan-2016
240-323 OS,2000
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240-323, Part I Operating - System
Structures
Department of Computer Engineering, PSU Wannarat Suntiamorntut
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Components
• Process Management - process : a program in execution, job - process needs certain resources : CPU time, memory file, I/O device - process is not program!!! - program is a passive entity, whereas a process is an active entity. - process is unit of work in system :
--> Operating system process--> User process
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Components
- Os is responsible for the following activities :
* created/deleted processes * mange resource requirements of a process
during its execution : CPU time, memory, I/O, ... * avoid interface between process * achieve cooperation between process
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Components
• Main-Memory Management
- Keep track of which parts of memory are currently being used and by whom.
- Decide which processes are to be loaded into memory when memory space becomes available.
- Allocate and deallocate memory space as needed.
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Components
• File Management
- Created/ deleted files or directories- map files onto secondary storage- backup files on stable storage media- manipulate files or directories
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Components
• I/O System Management
- memory management component includingbuffering, caching, and spooling.
- general device-driver interface- drivers for specific hardware devices
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Components
• Secondary-Storage Management
- Free-space management- Storage allocation- Disk scheduling
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Components
• Networking
Distributed system is a collection of processorsthat has its own local memory and clock, communicatewith one another through various lines.
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Components
• Protection System
Controlling the access of programs, processes or users to the resources defined by computer system.
• Command-Interpreter System- Interface between user and OS.- As same as command-line interpreter (shell).- Get next command statement and execute it.
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
Operating-System Services
OS services are provided for the convenience of programmer.• Program execution
System loads program into main memory,executes, and terminate (abnormal, normal).• I/O Operations
files or I/O devices• File-system manipulation
Copy or delete files• Communication
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
Operating-System Services
OS services are provided for multiusers• Resource allocation
CPU cycle, main memory, file storage, I/O• Accounting
status of user• Protection
Information for each users, Security
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Calls
• System call provided directed access to OS by programmers (assembly).• System call can be used from high level languages suchas copy file use :- Interactive system must be work in sequence.- bath system to define the parameter (file name)
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Calls : Copy file
Start Receive names of files Prompt messg
Read characterPut in parameterPass para.
Open fileError
Loop read input file Write output
Close both fileTerminate normally
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System Calls
• System call can provided into- process control- file manipulation- device manipulation- information manipulation- communications
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
System structure
• Simple Structure : small, simple and limited systems
Application Program
Resident system program
MS-DOS device drivers
ROM BIOS device drivers
240-323 OS,2000
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Department of Computer Engineering, PSU Wannarat Suntiamorntut
UNIX System structure
USERSShell and commands compilers and interpreters system libraries
System call interface to kernel
Signals terminalhandlingcharacter I/O systemterminal drivers
File systemswapping block I/O systemdisk and tape
CPU schedulingpage replacementdemand pagingvirtual memory
Kernel interface to kernel
Terminal controller device controller memory controller disk and tape