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CHAPTER 1 : INTRODUCTION OF OPERATING SYSTEM, CHAPTER 2 : MEMORY…
CHAPTER 1 : INTRODUCTION OF OPERATING SYSTEM
WHAT IS A OPERATING SYSTEM ?
An operating system (OS) is software that manages computer hardware and software resources and provides common services for computer programs.
DEFINITION OF OPERATING SYSTEM
-A group of program that acts as an intermediary between a user and the computer hardware .
-Allow the program to communicate with one another
-user -application -operating system - hardware
CHAPTER 2 :
MEMORY MANAGMENT
Memory Management Goals
Allocating space
available pool of memory
Function of Memory Manager
preserve the space in main memory occupied by the operating system
in charge of main memory
reclaim the memory, memory manager deallocate memory
Memory Management Strategies in Memory Allocation
Fetch
-virtual memory manager to determine when a page is copied from disk to memory
Placement
-The rules used by virtual memory manager to determine where the virtual pages to be loaded
Replacement
-VM manager to determine which virtual page must be removed from memory to make room for new page.
-First fit -Best fit -Worst fit
Process Management
The computer system today allow multiple programs to be loaded into memory and to be executed concurrently but at one point of time only one program is in execution or rather at most one instruction is executed on behalf of the process.
INTERRUPT
-An interrupt is an electronic signal.
-The operating system then handles the interrupt
-after the interrupt is processed, the dispatcher starts an application program.
Method for handling deadlock
. Prevention and avoidance of deadlock
Ignore the deadlock
Avoid the deadlock
. Detect and Recover from Deadlock
Scheduling Concept
-The basis of multitasking is scheduling
-given process is to be run, within a multitasking environment called scheduling
Process Scheduling
-need for schedule processes on your system
-process to run first if there have more than one process is run able.
-Scheduler is part of O/S which make this decision.
Scheduling Creteria
CPU utilization (Penggunaan CPU)
Throughput (Daya Pemprosesan)
Turnaround time (Masa pusingan)
Waiting time ( Masa menunggu)
Response time (Masa tindakbalas)
CPU Scheduler
-None - Preemptive
-Preemptive
Purpose of CPU Scheduler
Long term scheduler / Job Scheduler
Medium Term Scheduler
Short term scheduler/ CPU scheduler/ Dispatcher
CHAPTER 3 : FILE MANAGEMENT
Concept of the File
-be define as a system that an operating system uses to keep track of different files.
-file management aims to provide a convenient programming environment for the users of the system.
File Access Techniques
-Sequential
-Direct
-Indexed
4 Types of Directory Structure
-Storage structure
-Directory structure
-Single-level directory
-Two-level directory
Methods of File Allocation
-how to allocate space to these files so that disk space is utilized effectively and files can be accessed quickly
a.Contiguous file allocation
b.Linked file allocation
c.Indexed file allocation
Free Space Management
a.Using bitmaps
b.Linked List