Found 691 Articles for Computer Science

Many operating systems are not based on one model of the operating system. They may contain multiple operating systems that have different approaches to performance, security, usability needs etc. This is known as a hybrid operating system.The Hybrid operating system may allow one operating system to fulfil one set of requirements and the other operating system to fulfil the rest. For example, one of the operating systems may provide user interface, applications monitoring etc. while the other operating system may be a high-performance operating system that does not provide the same services as the first operating system.Features of Hybrid Operating ... Read More

Solaris is a Unix based operating system that was developed by Sun Microsystems and after its acquisition by Oracle, it is known as Oracle Solaris. It is known for its scalability and its innovative features such as DTrace, ZFS, Time Slider etc. Solaris is a microkernel design and it is not possible to create a monolithic Solaris kernel.A diagram demonstrating the structure of the Solaris operating system is as follows −The different components in the Solaris operating system structure are −HardwareThis includes the physical components of the computer system such as monitor, keyboard, data storage etc.I/O BufferI/O devices are very ... Read More

The interface between a process and an operating system is provided by system calls. In general, system calls are available as assembly language instructions. They are also included in the manuals used by the assembly level programmers.Unix System CallsSystem calls in Unix are used for file system control, process control, interprocess communication etc. Access to the Unix kernel is only available through these system calls. Generally, system calls are similar to function calls, the only difference is that they remove the control from the user process.There are around 80 system calls in the Unix interface currently. Details about some of ... Read More

iOSThe iOS is the operating system created by Apple Inc. for mobile devices. The iOS is used in many of the mobile devices for Apple such as iPhone, iPod, iPad etc. The iOS is used a lot and only lags behind Android in terms of popularity.The iOS architecture is layered. It contains an intermediate layer between the applications and the hardware so they do not communicate directly. The lower layers in iOS provide the basic services and the higher layers provide the user interface and sophisticated graphics.The layered architecture of iOS is given as follows −AndroidAndroid is an operating system ... Read More

The GRUB (Grand Unified Bootloader) is a bootloader available from the GNU project. A bootloader is very important as it is impossible to start an operating system without it. It is the first program which starts when the program is switched on. The bootloader transfers the control to the operating system kernel. GRUB Features GRUB is the default bootloader for many of the Linux distributions. This is because it is better than many of the previous versions of the bootloaders. Some of its features are: GRUB supports LBA (Logical Block Addressing Mode) which puts the addressing conversion used ... Read More

The Erasable Programmable Read Only Memory is a memory chip that does not lose data even when the power is switched off. This is a non-volatile memory type i.e. it retains data even when the power is switched off. Each EPROM is individually programmed by an electronic device. After that, the data can be erased by exposing the EPROM to strong ultraviolet light.An EPROM contains a transparent fused quartz window at the top of the package which allows exposure to ultraviolet light. The silicon chip is visible from this window.EPROM OperationA single field effect transistor constitutes a storage location. This ... Read More

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