Introduction to Operating Systems
General Definition An OS is a program which acts as an interface between computer system users and the computer hardware. It provides a user-friendly environment Read More »
Operating Systems
History of Operating Systems
It all started with computer hardware in about 1945s. Computers were using vacuum tube technology. Programs were loaded into memory manually using switches, punched cards, or paper Read More »
Basic Concept of Processes
Definition: A process is an executing program, including the current values of the program counter, registers, and variables.The subtle difference between a process and a program Read More »
Process States
we have already read the concept of process ,not let us see what it is process states, please check the below figure States Read More »
Process Scheduler
What is Scheduler in Operating System ? If we consider batch systems, there will often be more processes submitted than the number of processes that can Read More »
Operating System Performance Criteria
In order to achieve an efficient processor management, OS tries to select the most appropriate process from the ready queue. For selection, the relative importance of Read More »
Processor Scheduling algorithms
Now, let’s discuss some processor scheduling algorithms again stating that the goal is to select the most appropriate process in the ready queue. For the Read More »
Memory Management-Fixed Partitioning,Variable Partitioning
In a multi-programming system, in order to share the processor, a number of processes must be kept in memory. Memory management is achieved through memory management algorithms. Read More »
OS Memory Management – Paging
Why Paging is Required ? Paging permits a program to allocate noncontiguous blocks of memory. The OS divide programs into pages which are blocks of small Read More »
How to Implement The Page Table?
Every access to memory should go through the page table. Therefore, it must be implemented in an efficient way. a. Using fast dedicated registers Keep Read More »
Memory Management – Segmentation
Concept Of Segmentation in Operating System In segmentation, programs are divided into variable size segments, instead of fixed size pages. Every logical address is formed Read More »
OS Virtual Memory-Demand Paging
Lets Discuss Virtual Memory Over here ,All the memory management policies we have discussed so far, try to keep a number of processes in the memory Read More »
Performance Calculation of Demand Paging System
If there is no page fault, effective access time is effective memory acces time is eatNO-PF = emat If there is a page fault, Read More »
OS Dirty bit
Why Dirty Bit? What is Dirty Bit? In order to reduce the page fault service time, a special bit called the dirty bit can be associated Read More »
Page Replacement Algorithms
A page replacement algorithm determines how the victim page (the page to be replaced) is selected when a page fault occurs. The aim is to minimize Read More »