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

A computer system is basically a machine that simplifies complicated tasks. It should maximize performance and reduce costs as well as power consumption. The different components in the Computer System Architecture are Input Unit, Output Unit, Storage Unit, Arithmetic Logic Unit, Control Unit etc.A diagram that shows the flow of data between these units is as follows −The input data travels from input unit to ALU. Similarly, the computed data travels from ALU to output unit. The data constantly moves from storage unit to ALU and back again. This is because stored data is computed on before being stored again. ... Read More

Clustering systems are similar to parallel systems as they both have multiple CPUs. However a major difference is that clustered systems are created by two or more individual computer systems merged together. There are two types of Clustering systems i.e. asymmetric and symmetric clustering systems. Details about these are given as follows −Asymmetric Clustering SystemIn this system, one of the nodes in the clustered system is in hot standby mode and all the others run the required applications. The hot standby mode is a failsafe in which a hot standby node is part of the system . The hot standby ... Read More

Clustered systems are similar to parallel systems as they both have multiple CPUs. However a major difference is that clustered systems are created by two or more individual computer systems merged together. Basically, they have independent computer systems with a common storage and the systems work together.Clustered System StructureThe structure of a clustered system is given as follows −Some details about the above structure are −The clustered system contains tightly couples individual nodes. However, the degree of coupling in the system may vary. Some jobs may require constant communication between the nodes while there are also jobs that may only ... Read More