Definition:- The interface between the operating system and the user programs in defined by the set of  "extended instruction" that the operating system provides. These extended instructions are known as system calls. User programs communicate with the operating system and request services from it by making system calls. There exists a library procedure  corresponding to each system call that user program can call. This procedure puts the parameters of the system call in a specific place, such as the machine registers, and then issues a TRAP instruction to start the operating system. When the operating system gets control after the TRAP, it examines the parameters to see if they are valid, and if so, performs the work requested. When it is finished, the operating system puts a status code in a register, telling whether it succeeded of failed, and executes a RETURN FROM TRAP instruction, to return control back to the library procedure. the library procedure then returns to th

Machine Learning is a tool for turning information into knowledge. Machine learning techniques are used to automatically find the valuable underlying patterns within complex data that we would otherwise struggle to discover. The hidden patterns and knowledge about a problem can be used to predict future events and perform all kinds of complex decision making. Tom Mitchell gave a "well-posed" mathematical and relational definition that " A computer program is said to learn from experience E with respect to some task T and some performance measure P, if  its performance on T, as measured by P, improves with experience E ". For example :- A checkers learning problem:                        Task(T): Playing checkers.                         Performance measures (P): Performance of games won.                         Training Experience (E): Playing practice games against itself. Need for Machine Learning:- Ever since the technical revolution, we've been generating an

 The various types of operating systems are as follows - (i) Desktop system  (ii) Multiprocessor system (iii) Clustered system (iv) Handheld system  (v) Real-time system  (vi) Multitasking  (vii) Multiprogramming  (viii) Distributed system (i) Desktop system :- Personal computers PCs introduced in the 1970s. During their first decade, the CPUs in PCs lacked the features needed to protect an operating system from use programs. Therefore, PC operating systems were neither multiuser nor multitasking. However, PC operating systems have changed with time; instead of maximizing CPU and peripheral utilization, the systems opt for maximizing user convenience and responsiveness. These systems include PCs running Microsoft Windows and the Apple Macintosh. The MS-DOS operating system from Microsoft has been superseded by multiple flavors of Microsoft Windows, and IBM has upgraded MS-DOS to the OS/2 multitasking system. The Apple Macintosh operating system has been ported to more advanced hardwar

Protect our data from Cyber Crime:- some easy tips to protect computer from the growing theats:- 1) Create backup of important data 2) Keep your software updated 3) Use security programs 4) Protect your password 5) Participation in social networking 6) Strengthen your home network 1) Create backup of important data:- Backup of all the important files whether personal or professional should be created. Getting used to back up your files regularly is the first step towards security of your personal computer.  2) Keep your software updated:- This is especially important with your operating system and Internet security software. Cyber criminals frequently use known exploits, of flaws, in your software to gain access to your system. 3) Use security programs:- If your system does not have data protection software to protect online, then by all means buy Internet security programs for your computer. 4) Protect your password:- Try creating a password that consists of a combination of letters (

Web Browser   A web browser is the program you use to view web pages & navigate the world wide web. Large variety of web browsers are available for every computer platform links. It is a client / program / software / tool through which we sent HTTP request to web server. Main purpose of web browser is to locate the current on the www & display in the form of webpage, image, audio or video on client computer. It is called as client because it connect the web server for desired information & if the requested data is available in the webserver then it will send back the requested information to web browser. Web browsers are capable to understand the HTML, JAVASCRIPT, AJAX etc. Web browser for mobile are called as Micro browsers.  

  HTTP  It is stands for Hypertext Transfer Protocol. It is a protocol used by WWW for data communication between web client (browser) & web server. HTTP protocol defines how messages are prepared & transmitted during web client & web server communication. It also defines what actions web server browser should take in response to various commands. HTTP is a TCP/IP based communication protocol, that is used to deliver data which may be HTML files, image files, query results, etc. On the world wide web(www). The defaults port is TCP 80, but other ports can be used as well. Basic Features of HTTP :- There are three features that make HTTP a simple but powerful protocol. 1. Connectionless Protocol :- HTTP is a Connectionless protocol. HTTP client initiates a request and waits for a response from the server. When the server receive the request, the server processes the request and sends back the response to the HTTP client after which the client disconnecteds the connection. Th

HTTP Request and Response Methods:-  The operation of Hypertext Transfer Protocol(HTTP) involves the communication between a Hypertext Transfer Protocol(HTTP) client application (Usually web browser) and a Hypertext Transfer Protocol (HTTP). Server application (Web server like IIS). Hypertext Transfer Protocol (HTTP) uses Transmission Control Protocol (TCP) as the Transport Layer Protocol at well known port number 80. Once the TCP connection is established, the two step in Hypertext Transfer Protocol (HTTP) communication are - 1. HTTP Client Request :-  Hypertext Transfer Protocol (HTTP) client sends an Hypertext Transfer Protocol (HTTP) Request to the Hypertext Transfer Protocol. Hypertext Transfer Protocol (HTTP) sever acooding to the HTTP standard, specifying the information the client like to retrieve from the Hypertext Transfer Protocol (HTTP) server. 2. HTTP Server Response :- Once the Hypertext Transfer Protocol (HTTP) Request arrived at the Hypertext Transfer Protocol (HTTP) se