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Articles by Bhanu Priya
Page 52 of 106
Differentiate between programmed I/O and interrupt driven I/O.
The differences between programmed (Input/Output) I/O and interrupt-driven I/O are as follows −Programmed I/OThis I/O technique is the simplest to exchange data between external devices and processors. In this technique, the processor or Central Processing Unit (CPU) runs or executes a program giving direct control of I/O operations.Processor issues a command to the I/O module and waits for the operation to complete. Also, the processor keeps checking the I/O module status until it finds the completion of the operation.The processor's time is wasted, in case the processor is faster than the I/O module. Its module is considered to be a ...
Read MoreWhat is buffering and spooling in a batch processing operating system?
To improve the performance and to avoid the CPU idle time the operating system uses two approaches which are explained below in detail.BufferingIt is a method of overlapping input, output and processing of a single job.After reading the data, the CPU is about to start operating on it, the input device is instructed to begin the next input immediately. The CPU and the input device are both busy. By the time the CPU is ready for the next data item the input device will have to finish its reading.The CPU then begins processing the next data while the input device ...
Read MoreWhat is the computer architecture that supports the operating system?
There are different operating systems for different kinds of computers and processors. They are divided into different categories.Single processor systemSingle CPU or processor that manages the computer and it runs on a different operating system, and performs a number of tasks using one processor called a single processor system.In a single processor system different types of tasks can be performed like disk control, user control, system control etc.The figure given below depicts the single processor system −Multiprocessor systemWhen one task can be performed by using multiple processors then it is called a multiprocessor system.In a multiprocessor system a number of ...
Read MoreWhat are the user and system goals of Operating Systems?
The design of the operating system should be defined by the goals and specifications which are affected by hardware and systems. Thus there would be user goals and system goals for an OS.User GoalsThe user goals or requirements should be as follows −The OS usage should be convenientShould be easy to use and easy to learnShould be safe and secure to use and information handling, and security should be robustShould be fast in response to the user requestsSystem GoalsThe system design requirements should be as follows −The OS should be easy to design, maintain and also to implement.Updates should be ...
Read MoreWhat is a system call?
System call provides an interface between user program and operating system. It is represented as follows −When the user wants to give an instruction to the OS then it will do it through system calls. Or a user program can access the kernel which is a part of the OS through system calls.It is a programmatic way in which a computer program requests a service from the kernel of the operating system.Program executes in two modes as follows −User mode − Cannot access any hardware resources, which perform only the user operations.Kernel mode − Can access hardware resources like RAM, ...
Read MoreWhat are the different system calls in the operating system?
The different system calls are as follows −System calls for Process managementSystem calls for File managementSystem calls for Directory managementLet us understand them one by one.System calls for Process managementA system is used to create a new process or a duplicate process called a fork. The duplicate process consists of all data in the file description and registers common. The original process is also called the parent process and the duplicate is called the child process.The fork call returns a value, which is zero in the child and equal to the child’s PID (Process Identifier) in the parent. The system ...
Read MoreWhat are the interrupt stages and processing?
Instruction cycle consists of fetch, execute and interrupt stage show in below diagram −If any interrupt occurs, it is indicated by an interrupt flag. The CPU will go to interrupt handler routine. Interrupt handler then checks the type of interrupt and executes the appropriate function. It involves overhead but still better than the CPU waiting for I/O completion or other activities.Interrupt handler activates most prior able activity first and later deferrable part will be handled.ExampleBlock of data arrives on the network line.Kernel marks the presence of data (urgent part) and gives the CPU back to the process that was running ...
Read MoreWhat is the purpose of a register in a CPU and what are special purpose registers?
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 MoreDifferentiate between user and control register in CPU.
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 MoreWhat is the CPU control register?
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 ...
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