We know that an operating system is a resource allocator and it manages all the resources which are associated with the system.Let us see how operating system design is related to basic elements of a computer systemRegistersRegisters are available in the processor. These registers are used for storage and data transfer in the processor.There are registers which perform the operation of storage of data. It is known as data register (DR) and the register which stores the address known as address register (AR) and program counter (PC) register which is used for storing the address of next instruction.After the instructions ... Read More

An instruction is a set of codes that the computer processor can understand. The code is usually in 1s and 0s, or machine language. It contains instructions or tasks that control the movement of bits and bytes within the processor.Example of some instruction sets −ADD − Add two numbers together.JUMP − Jump to designated RAM address.LOAD − Load information from RAM to the CPU.Types of Instruction SetGenerally, there are two types of instruction set used in computers.Reduced Instruction set Computer (RISC)A number of computer designers recommended that computers use fewer instructions with simple constructs so that they can be executed ... Read More

A CPU register is a small and temporary storage containing a set of data holding places that are part of the computer processor. A register holds an instruction, a storage address, or any kind of data.Before trying to understand some special purpose registers, let us try to understand the difference between General purpose and special purpose registers.Special purpose registers hold the status of a program. These registers are designated for a special purpose. Some of these registers are stack pointer, program counter etc.General purpose registers hold the temporary data while performing different operations. Some of these registers are accumulator, BX ... Read More

User registers can read or write by machine instructions. The user registers are divided into data registers and address registers.Data registersThese registers hold the numeric data values like integers and, in some architectures, hold floating-point values, characters, small bit arrays and other data. In low end CPUs, a special data register, called the accumulator, is used implicitly for many operations.Address registersThese registers hold addresses and are used by instructions to indirectly access primary memory.Some of the processors contain registers that are used to hold an address or to hold numeric values. In some cases, it is used as an index ... Read More

Control register is called a processor register that changes or controls the general behaviour of a CPU or other services in the system.The common tasks performed by control registers are interrupt control, switching the addressing mode, paging control, and coprocessor control.Types of CPU Control RegisterThe different types of CPU control register are as follows −The control registers are those extra registers that are visible only in kernel mode.CR0 - Reads as 0, read-onlyCR1 - For general-purpose useCR2 - For general-purpose useCR3 - For general-purpose use and TLB interfaceCR4 - Processor Status RegisterCR5 - Interrupt Status RegisterCR6 - Interrupt Mask RegisterCR7 ... Read More

General purpose registers are additional registers that are present in CPU which is used for either memory address or data whenever needed. For example, storing current register content when there is an interruption.8086 processorLet us consider an 8086 processor. There are eight general purpose register in 8086 microprocessor which are explained below −AXThis is the accumulator of 16 bits and is separated into two 8-bits registers AH and AL to likewise perform 8-bits instruction. It is usually utilized for arithmetical and logical directions, yet in 8086 chips it isn't required to have an accumulator as the objective operand.Example − ADD ... Read More

I/O Structure consists of Programmed I/O, Interrupt driven I/O, DMS, CPU, Memory, External devices, these are all connected with the help of Peripheral I/O Buses and General I/O Buses.Different types of I/O Present inside the system are shown below −Programmed I/OIn the programmed I/O when we write the input then the device should be ready to take the data otherwise the program should wait for some time so that the device or buffer will be free then it can take the input.Once the input is taken then it will be checked whether the output device or output buffer is free ... Read More

Let us learn about machine virtualization.Machine VirtualizationThe diagram given below shows the machine virtualization −Operating system virtualizationThe diagram given below shows the operating system virtualization −DifferencesThe major differences between Machine virtualization and operating system virtualization are as follows −Machine virtualizationOperating system virtualizationIt refers to the creation of a virtual machine that acts like a real computer.It is a part of virtualization and is a type of server virtualization.It can be done by extracting the physical hardware with the help of VVM (Virtual Machine Monitor).With OS virtualization nothing is pre installed/ permanently loaded on the local device & no hard-disk drive ... Read More

Let us understand what multiprogramming is.MultiprogrammingIt is the ability of an operating system which executes more than one program on a single processor machine. More than one task or program can store or reside into the main memory at one point of time.In this concept the CPU executes some part of one program, and then continues with another part of the program, and so on. Because of this process, the CPU will never go into the idle state unless there is no process ready to execute at the time of Context Switching.The diagram given below depicts the multiprogramming −AdvantagesThe advantages ... Read More

In embedded system, real time means the following −The system responds to an event or request within timing constraints.System must use a real time operating system, that system can interrupt a running task.The system must be predictable. The system guarantees that important tasks get run in fixed time constraints.Real time systems work in time constraints and provide estimated time for critical situations.Embedded systems provide specific functions in a large operating system.TasksGenerally, the tasks in the system are said to be fully pre-emptive and that are used to communicate with the rest of the system via data read at the beginning ... Read More