There are two modes of operation in the operating system to make sure it works correctly. These are user mode and kernel mode.A diagram that illustrates the transition from user mode to kernel mode and back again is as follows −The following are the modes −User Mode:The system is in user mode when the operating system is running a user application such as handling a text editor. The transition from user mode to kernel mode occurs when the application requests the help of operating system or an interrupt or a system call occurs.The mode bit is set to 1 in ... Read More

Supervisor mode or privileged mode is a computer system mode in which all instructions such as privileged instructions can be performed by the processor. Some of these privileged instructions are interrupt instructions, input output management etcThe privilege levels of different components in a system is given as follows −The kernel is the most privileged part of the computer system. There are some privileged instructions that can only be executed in kernel mode or supervisor mode. The the privilege reduces for device drivers and applications respectively.Features of Supervisor ModeSome of the important features of supervisor mode are as follows −Supervisor mode ... Read More

An operating system is a construct that allows the user application programs to interact with the system hardware. Since the operating system is such a complex structure, it should be created with utmost care so it can be used and modified easily. An easy way to do this is to create the operating system in parts. Each of these parts should be well defined with clear inputs, outputs and functions.Simple StructureThere are many operating systems that have a rather simple structure. These started as small systems and rapidly expanded much further than their scope. A common example of this is ... Read More

A beowulf cluster is formed using normal computers that are identical. These are arranged into a small local area network (LAN). There are programs that allow these computers to share processing among them.So beowulf clusters form a parallel processing unit using common personal computers.An image that displays the first beowulf cluster at Barcelona Supercomputing Center is as follows −Image Credit − By Vcarceler [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia CommonsFeatures of Beowulf ClustersSome important features of beowulf clusters are as follows −Beowulf clusters are formed using normal computers. There is no software that denoted a cluster as a beowulf cluster.A ... Read More

The hot standby mode is a fail-safe in which a hot standby component is part of an active system. If any component of the system fails, the hot standby component takes its place. In general, a hot standby can refer to any device, system etc. that overtakes operation from a failed device and reduces the startup delay that would otherwise be huge.A figure to further explain the hot standby mode is as follows −In general, it is expected that a system will have some failures. So, a hot standby is necessary to combat these failures.At the extreme, a hot standby ... Read More

Cache is a type of memory that is used to increase the speed of data access. Normally, the data required for any process resides in the main memory. However, it is transferred to the cache memory temporarily if it is used frequently enough.A diagram to better understand the data transfer in cache management is as follows −Cache PerformanceThe cache performance can be explained using the following steps −If a process needs some data, it first searches in the cache memory. If the data is available in the cache, this is termed as a cache hit and the data is accessed ... Read More

Memory management plays an important part in operating system. It deals with memory and the moving of processes from disk to primary memory for execution and back again. Some basic concepts related to memory management are as follows −Virtual Address Space and Physical Address SpaceThe address generated by the CPU is known as the virtual address and the address seen by the memory is known as the physical address. In compile time and load time address binding schemes, both the virtual and physical address are the same. They differ only in the execution time address binding scheme.All the logical addresses ... Read More

A distributed system contains multiple nodes that are physically separate but linked together using the network. All the nodes in this system communicate with each other and handle processes in tandem. Each of these nodes contains a small part of the distributed operating system software.A diagram to better explain the distributed system is −Types of Distributed SystemsThe nodes in the distributed systems can be arranged in the form of client/server systems or peer to peer systems. Details about these are as follows −Client/Server SystemsIn client server systems, the client requests a resource and the server provides that resource. A server ... Read More

Dynamic RAM (DRAM) is a type of semiconductor memory that uses capacitors to store the bits. The charging and discharging of the capacitor represents 0 and 1 i.e. the two possible values that can be stored in a bit.The DRAM is a volatile memory i.e. the data in memory is lost when power is switched off. However, it still displays some data remanence. DRAM is low cost compared to SRAM so it is primarily used in main memory.The following displays a DRAM:Versions of DRAMAsynchronous DRAMThis was the first type of DRAM in use but was gradually replaced by synchronous DRAM. ... Read More

Random access memory (RAM) is a type of primary storage. It allows the user to randomly access any part of the data regardless of its position in roughly the same time. This is not possible using other storage devices such as hard disks, CD’s etc. because they have physical constraints such rotation speeds, arm movements etc.RAM is mostly volatile i.e. the data in RAM is dependent on the power and as lost when power is switched off. However, there are some non - volatile versions of RAM also available.There are mainly two types of RAM available i.e. Static RAM (SRAM) ... Read More