Operating System

Operating System:-

An operating system is a program that manages the computer hardware.

It also provides a basis for application programs and acts as a intermediary between computer user and computer hardware.

Some Operating Systems

Windows
Linux
Ubuntu
Mac OS X
IOS
Android

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Main goals of Operating System

Convenience-Provides convenient to user
Efficiency-Operating system allows the computer system resources to be used in an efficient manner
Ability to evolve:- An operating system should be constructed in such a way as to permit the effective development, testing, and introduction of new system functions without interfering with service.

Operating System Basics

A modern general purpose computer system consists of one or more central processing unit(CPU s) and a number of device controller connected through a common bus that provides access to shared memory.

Each device controller is in charge of a specific type of device.

The central processing unit (CPU) and the device controller can execute concurrently, competing for memory cycles.
To ensure orderly access to the shared memory, a memory controller is provided whose function is to synchronize access to the memory.

Important Terminology :-

Bootstrap Program

The initial Program that runs when a computer is powered up or rebooted.
It is stored in ROM.
It must know how to load the operating system and start executing that system.
It must locate and load into memory the Operating System kernel.

Interrupt :-

The occurrence of an event is usually signaled by an interrupt from hardware or software.
Hardware may trigger an interrupt at any time by sending a signal to the CPU , usually by the way of the system bus.

System Call

Software may trigger an interrupt by executing a special operation called system call.
When the CPU is interrupted, it stops what it is doing and immediately transfers execution to a fixed location
The fixed location usually contains the starting address where the service routine of the interrupt is located.
The interrupt service routine executes on completion, the CPU resumes the interrupted computation.

Read Basic elements of computer

Read operating system services

Comments

Types of Operating System Batch Operating system Time sharing Operating system Distributed Operating system Network Operating system Real Time Operating system Multi programming/Processing/Tasking Operating system Mobile Operating System Batch Operating System In a Batch operating system the similar jobs are grouped together into batches with the help of some operators and these batches are executed one by one. For example, suppose we have ten programs, some are written in c++ programming language, Some are written in c programming language and the rest are written java programming language. Now, every time we run these programs one by one, we have to load the compiler of that particular language and then run the code. But if we do a batch of these ten programs, The advantage with this approach is that for the c++ batch, you only need to load the compiler once. Similarly, for Java and C , the compiler only needs to load once an...

Python Variables

variables,the name itself implies that a variable is something which can change. Variables are like containers for storing our data values in memory. we can change the data in variables, in python everything is an object and variables are like names given to the object, by labeling them we can easily access them. In other high level languages like C programming language, c++ programming language, and java programming language. etc., we need to declare the datatype of the variable , but in python it will automatically recognize the type of data you are storing in a variable. ** Remember that a variable is a name which is given to a value not to the memory. Declaring a variable is very easy you need to assign a value or a string using '=' operator. >>> p=9 >>> print(p) 9 Assigning a single value to multiple variables We can assign a single value to multiple variables. >>> a=b=c=56 >>> a 56 >>> b 56 >>> c 5...

Even or Odd Number and Factorial of a Number in Python Programming

1. To Check if the given number is even or odd If a number is completely divided by 2 then it is even number. When the number is divided by 2, we use the remainder operator % to calculate the remainder. If the remainder is not zero, the number is odd. SOURCE CODE:- n= int ( input ( "enter any number:- " )) if (n% 2 == 0 ): print (n , 'is even number' ) else : print (n , 'is odd number' ) OUTPUT 1st Run enter any number:- 2 2 is even number 2nd Run enter any number:- 3 3 is odd number In the above code we use "Simple if" statement. In the above program, we ask the user for input and check if the number is odd or even. 2.Factorial number Factorial of a number defined as the product of all numbers from 1 to given number. For example 5!(5 factorial)=5*4*3*2*1 is 120. Note = factorial of 0 is 1 SOURCE CODE n= int ( input ( "Enter any number:- " )) fact= 1 for i in range ( 1 , n+ 1 ): fact=fact*i print ( 'factorial of' , ...

DATA TYPES IN PYTHON | (Numeric,Boolean, Dictionary)

Previous Variables in Python In python programming language everything is an object and data type tells us which types of value the object is. Data types are classified into five types in Python programming language, they are:- Best Laptop for Web Development in 2021. NUMERIC DATATYPES BOOLEAN DATATYPES DICTIONARY SEQUENCE DATATYPE SET type() method Type method is used to know what type of data we are using. Numeric Data Types Numeric type consists of numerical value data types for example whenever we assign a decimal value or numbers to variables then it comes under numeric data types. It contains : int float complex type Int or Integer It is a data type where the value given by the user can be positive or negative and can be of any length that means it can be a big integer or small integer but it should not be a fraction or a decimal value. #Python Program to # demonstrate int value p= 5556677 print ( type (p)) q=- 45 print ( type (q)) #output < class 'int' >...

Functions of Operating System

Operating System is an interface between the user and the hardware and enables the interaction of a computer's hardware and software. Also, an operating system is software that performs all the basic functions of file management, storage management, process management, managing input and output, and controlling peripherals such as disk, drivers and printers. Functions of Operating System Device Management File Management Memory Management Process Management Mastermind Storage Management Handling input/output operations Security Functions of Operating System Device Management Operating system manages device communication via their respective drivers. It does the following activities for device management: Keeps tracks of all devices, input/output controller is responsible for this task. Decides which process gets the device when and for how much time Allocates the device in an efficient way. De-allocates dev...

Computer System Architecture

Based on number of general purpose processors computer systems are classified into three types.They are: Single Processor Systems. Multiprocessor Systems. Clustered Systems. Single Processor Systems From the name it is very clear that it has only single processor. A major central processing unit that can execute a set of general utility instructions, including user process instructions. There are some other special purpose processors present that performs device specific task. In the single processor system apart from the main central processing unit(CPU) there are also other processors which are present which does not do the general purpose task but it performs some device specific task. It means that we have a certain devices in our computers like keyboard, disk, etc. for all this they may be some microprocessor which is specified to do a specific task related to that device like for example keyboard, when we press a key on our keyboard the keystroke has to be converted to...

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