Technical Questions

A shell is an interactive user interface to an operating system services that allows an user to enter commands as character strings or through a graphical user interface. The shell converts them to system calls to the OS or forks off a process to execute the command. System call results and other information from the OS are presented to the user through an interactive interface. Commonly used shells are sh,csh,ks etc.

The data bus is Bi-directional because the same bus is used for transfer of data between Micro Processor and momory of input / output devices in both the direction.

Multi programming: Multiprogramming is the technique of running several programs at a time using timesharing. It allows a computer to do several things at the same time. Multiprogramming creates logical parallelism. The concept of multiprogramming is that the operating system keeps several jobs in memory simultaneously. The operating system selects a job from the job pool and starts executing a job, when that job needs to wait for any i/o operations the CPU is switched to another job. So the main idea here is that the CPU is never idle. 

Multi tasking: Multitasking is the logical extension of multiprogramming .The concept of multitasking is quite similar to multiprogramming but difference is that the switching between jobs occurs so frequently that the users can interact with each program while it is running. This concept is also known as time-sharing systems. A time-shared operating system uses CPU scheduling and multiprogramming to provide each user with a small portion of time-shared system. 

Multi threading: An application typically is implemented as a separate process with several threads of control. In some situations a single application may be required to perform several similar tasks for example a web server accepts client requests for web pages, images, sound, and so forth. A busy web server may have several of clients concurrently accessing it. If the web server ran as a traditional single-threaded process, it would be able to service only one client at a time. The amount of time that a client might have to wait for its request to be serviced could be enormous. So it is efficient to have one process that contains multiple threads to serve the same purpose. This approach would multithread the web-server process, the server would create a separate thread that would listen for client requests when a request was made rather than creating another process it would create another thread to service the request. To get the advantages like responsiveness, Resource sharing economy and utilization of multiprocessor architectures multithreading concept can be used.

A real time process is a process that must respond to the eventswithin a certain time period. A real time operating system is an operating system that can run realtime processes successfully.

In Computers ::

A network is a collection of computers, servers, mainframes, network devices, peripherals, or other devices connected to one another to allow the sharing of data.

An excellent example of a network is the Internet, which connects millions of people all over the world. Below is an example image of a home network with multiple computers and other network devices all connected to each other and the Internet.

Ex:: LAN, WAN, MAN, WLAN,...

In Business view::

Networking is defined as the act of making contact and exchanging information with other people, groups and institutions to develop mutually beneficial relationships.

Distributed systems work in a network. They can share the network resources, communicate with each other.

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol