Operating Systems have become quite complex and multifaceted with the advancement of time. However, that also means it is getting more and more difficult to design operating systems that satisfy all the specifications required these days. There are no complete solutions possible for design problems, but some approaches are more successful than others.Design Requirements in Operating SystemThe design requirements are quite hard to specify in an operating system. They are basically divided into two parts: User design requirements and System design requirements. Details about these are given as follows −User Design RequirementsThe operating system should be convenient, easy to use, ... Read More

A command line interpreter allows the user to interact with a program using commands in the form of text lines. It was frequently used till the 1970’s. However, in modern times many command line interpreters are replaced by graphical user interfaces and menu-driven interfaces.Usage of Command Line InterpretersCommand line interpreters are more useful than graphical user interfaces in some cases. Details about these cases are given as follows:Command line interpreters have a large range of commands and queries available for different operations. Also, it is much faster to type than to click as is done using graphical user interfaces.There are ... Read More

An Application Programming Interface (API) contains software building tools, subroutine definitions as well as communication protocols that facilitate interaction between systems. An API may be for a database system, operating system, computer hardware or a web-based system.An Application Programming Interface makes it simpler to use certain technologies to build applications for the programmers. API can include specifications for data structures, variables, routines, object classes, remote calls etc.A diagram that shows the API in the system is as follows −Uses of Application Programming InterfacesAPI’s are useful in many scenarios. Some of these are given in detail as follows −Operating SystemsThe interface ... Read More

A shell script is a list of commands in a computer program that is run by the Unix shell which is a command line interpreter. A shell script usually has comments that describe the steps. The different operations performed by shell scripts are program execution, file manipulation and text printing. A wrapper is also a kind of shell script that creates the program environment, runs the program etc.Types of ShellsThere are two major types of shells in Unix. These are:Bourne ShellThis is the default shell for version 7 Unix. The character $ is the default prompt for the bourne shell. ... Read More

GUI is an interface that allows users to interact with different electronic devices using icons and other visual indicators. The graphical user interfaces were created because command line interfaces were quite complicated and it was difficult to learn all the commands in it.In today’s times, graphical user interfaces are used in many devices such as mobiles, MP3 players, gaming devices, smartphones etc.The below diagram provides the position of the graphical user interface with respect to the computer system −Elements in Graphical User InterfaceGraphical User Interface makes use of visual elements mostly. These elements define the appearance of the GUI. Some ... Read More

A debugger program is one that allows the user to view another program line by line. This allows the user to identify incorrect code and find out how a program flows. The debugger lets the user see how their program is viewed by the computer.A debugger is very useful to find semantic errors in the program. So, it is necessary as it helps the programmer visualize program flow. A debugger may take practise to use, but it is well worth it as it reduces the time taken to perfect a program.Features of a Debugger ProgramDebugger programs offer basic features such ... Read More

There are mainly two categories of programs i.e. application programs and system programs. A diagram that demonstrates their place in the logical computer hierarchy is as follows −Application ProgramsThese programs perform a particular function directly for the users. Some of the common application programs include Email, web browsers, gaming software, word processors, graphics software, media player etc.All of these programs provide an application to the end users, so they are known as application programs. For example: a web browser is used to find information while a gaming software is used to play games.The requests for service and application communication systems ... Read More

An operating system is a construct that allows the user application programs to interact with the system hardware. Operating system by itself does not provide any function but it provides an atmosphere in which different applications and programs can do useful work.There are many problems that can occur while designing and implementing an operating system. These are covered in operating system design and implementation.Operating System Design GoalsIt is quite complicated to define all the goals and specifications of the operating system while designing it.The design changes depending on the type of the operating system i.e if it is batch system, ... Read More

Modem is an abbreviation of “modulator demodulator”. It is a network device that modulates digital information or bits into analog signals for transmission at the sending end, and demodulates the analog signals to bits at the receiving end. Telephone modems enables data communication between two computers over voice – grade telephone lines. Purpose and Usage The computers are digital devices that are connected via analog local loops of the telephone networks. So, there is a need to convert the bits to analog signals so that they can be transmitted via the physical channels; and conversely convert analog signals in the ... Read More

In a telephone system, the local loop is a two-wire connection between the subscriber’s house and the end office of the telephone company. It is commonly referred to as the “last mile” of the telephone network. The loop may run from 1km to as far as 10 km.CompositionTraditionally, local loops are composed of twisted pair copper cables. The old local loops have several limitations − narrow bandwidth, high attenuation, distortion of symbols, crosstalk's etc.In recent times, copper wires are being replaced by fiber optic cables for faster and more accurate performance. Installation of fiber cables is popularly known as FttH ... Read More