Functions of Operating System

 functions of an operating System

·        Memory Management

·        Processor Management

·        Device Management

·        File Management

·        Security

·        Control over system performance

·        Job accounting

·        Error detecting aids

·        Coordination between other software and users

Memory Management

Memory management refers to management of Primary Memory or Main Memory. Main memory is a large array of words or bytes where each word or byte has its own address.

Main memory provides a fast storage that can be access directly by the CPU. So for a program to be executed, it must in the main memory. Operating System does the following activities for memory management.

·        Keeps tracks of primary memory i.e. what part of it are in use by whom, what part are not in use.

·        In multi programming, OS decides which process will get memory when and how much.

·        Allocates the memory when the process requests it to do so.

·        De-allocates the memory when the process no longer needs it or has been terminated.

Processor Management

In multiprogramming environment, OS decides which process gets the processor when and how much time. This function is called process scheduling. Operating System does the following activities for processor management.

·        Keeps tracks of processor and status of process. Program responsible for this task is known as traffic controller.

·        Allocates the processor(CPU) to a process.

·        De-allocates processor when processor is no longer required.

File Management

A file system is normally organized into directories for easy navigation and usage. These directories may contain files and other directions. Operating System does the following activities for file management.

·        Keeps track of information, location, uses, status etc. The collective facilities are often known as file system.

·        Decides who gets the resources.

·        Allocates the resources.

·        De-allocates the resources.

Device Management

OS manages device communication via their respective drivers. Operating System does the following activities for device management.

·        Keeps tracks of all devices. Program responsible for this task is known as the I/O controller.

·        Decides which process gets the device when and for how much time.

·        Allocates the device in the efficient way.

·        De-allocates devices.

Other Important Activities

Following are some of the important activities that Operating System does.

·        Security -- By means of password and similar other techniques, preventing unauthorized access to programs and data.

·        Control over system performance -- Recording delays between request for a service and response from the system.

·        Job accounting -- Keeping track of time and resources used by various jobs and users.

·        Error detecting aids -- Production of dumps, traces, error messages and other debugging and error detecting aids.

·        Coordination between other software and users -- Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.

Memory Measurement Unit in Computer

Memory Measurement  Unit-

Computer only understands the binary language. The information stored in the computer is in the form of 0`s and 1`s called bits.

A bit is the smallest unit of .A bit can have only a single value either 0 or 1. 

Geop Byte is The Highest Memory Measurement Unit

4 bits =1 nibble
8 bits = 1 Byte
1024 Bytes= 1 Kilo Byte
1024 Kilo Bytes = 1 Mega Byte
1024 Mega Bytes = 1 Giga Byte
1024 Giga Bytes = 1 Tera Byte
1024 Tera Bytes = 1 Peta Byte
1024 Peta Byte = 1 Exa  Byte
1024 Exa Byte = 1 ZettaByte
1024 Zetta Byte = 1 Yotta Byte
 1024 YB = 1 Bronto Byte
1024 Bronto Byte  = 1 Geop Byte

Information and Communications Technology (ICT)

Information and Communications Technology (ICT)

 

 ICT is an extension of information technology that include communication devices also. ICT is a term that combined information and communication technology.

ICT = Information Technology + Communication Technology

Information and communications technology (ICT) refers to all the technology used to handle telecommunications, broadcast media, intelligent building management systems, audiovisual processing and transmission systems, and network-based control and monitoring functions.

ICT (information and communications technology ) is  includes any communication device or application like,  radio, television, cellular phones, computer and network hardware and software, satellite systemsetc.

ICT has more recently been used to describe the convergence of several technologies and the use of common transmission lines carrying very diverse data and communication types and formats.

php navigations

PHP navigations

<?php

if($_SERVER['QUERY_STRING'] == "SoD")

 print "owns you!";

else

 print "don't front!";

?>

Description: Instead of calling files like ( index.php?str=blah ) , you could do ( index.php?SoD ) and it would print out "owns you!". You can add more strings in there, this is just an example.

   $vars = explode(",", urldecode(getenv('QUERY_STRING')));

   $v1 = array_shift($vars);

   $v2 = array_shift($vars);

   $v3 = array_shift($vars);

   switch ($v1) {

       case 'first.1': {

           print("This is v1, first string case 'file.php?first.1'.");

           break;

           }

      case 'first.2': {

      switch ($v2) {

           case 'second': {

               switch($v3) {

                   case 'third': {

                     print("This is v3, the last case 'file.php?first.2,second,third'.");

                     break;

                   }

               }

           }

       }

       }

   }

Description: This basically does what the 1st one does but with more strings and a different seperator rather than '&'. I don't really want to go into too much detail on the thread so if people are confused or need explaining, reply or PM me.

That's it for the navigation as I am not going to do the other due to they're everywhere else and I wanted to be different and show everyone this method.