Memory management plays an important part in the operating system. It deals with memory and the moving of processes from disk to primary memory for execution and back again.Some activities of an operating system with regards to memory management are −Memory AllocationA simple way to allocate memory is to provide the empty memory spaces to incoming processes as required. This can be done using the following algorithms −First-FitThe first available memory space that is large enough for the process purposes is allocated. Searching can start at the beginning or at the point where the last first-fit search ended.Best-FitThe smallest memory ... Read More

MS-DOS is an operating system created for personal computers. It was developed by Microsoft. It is a classic example of an operating system with a layered structure. MS-DOS operating system is split into various layers and each of the layers have different functionalities.Layering provides a distinct advantage in the MS-DOS operating system because all the layers can be defined separately and interact with each other as required. Also, it is easier to create, maintain and update the system if it is done in the form of layers. Change in one layer specification does not affect the rest of the layers. ... Read More

A process is an active program i.e a program that is under execution. It contains the program code, program counter, process stack, registers etc. Process Management deals with processes and the various mechanisms to handle them.The various activities that the operating system performs with regard to process management are mainly process scheduling and context switching. Details about these are given as follows −Process SchedulingThere are many scheduling queues that are used to handle processes. When the processes enter the system, they are put into the job queue. The processes that are ready to execute in the main memory are kept ... Read More

System programs provide an environment where programs can be developed and executed. In the simplest sense, system programs also provide a bridge between the user interface and system calls. In reality, they are much more complex. For example: A compiler is a complex system program.The user view of the system is actually defined by system programs and not system calls because that is what they interact with and system programs are closer to the user interface.An image that describes system programs in the operating system hierarchy is as follows −In the above image, system programs as well as application programs ... Read More

A microkernel is the minimum software that is required to correctly implement an operating system. This includes memory, process scheduling mechanisms and basic inter-process communication.A diagram that demonstrates the architecture of a microkernel is as follows −In the above diagram, the microkernel contains basic requirements such as memory, process scheduling mechanisms and basic interprocess communication. The only software executing at the privileged level i.e. kernel mode is the microkernel. The other functions of the operating system are removed from the kernel mode and run in the user mode. These functions may be device drivers, file servers, application interprocess communication etc.The ... Read More

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

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