I/O Devices Overview

The amount of digital data that is moved from one location to another within a specific time.

The specific use of the device, determined by its purpose.

The level of difficulty in operating the device.

Indicates whether data is transferred as a stream of bytes (character devices) or in large blocks (block devices).

A data encoding scheme used by the device, including character codes and parity conventions.

Involve the nature of errors, their reporting, consequences, and available responses.

Stores data in fixed-size blocks, transferring one block at a time. Examples include hard disks and flash drives.

Data is handled as a continuous stream of bytes. Examples include keyboards and printers.

Hardware components that allow computers to interact with the outside world by accepting input, producing output, or managing data.

A special program that translates instructions from the operating system to a specific I/O device, allowing communication and data transfer.

A dedicated connection point on a computer that allows I/O devices to connect and communicate.

A collection of shared wires with a predefined protocol used for communication between different components within a computer system.

These devices are designed for interaction with human users, providing input or displaying output.

These devices interact with electronic equipment, often used for sensing or controlling machines.

These devices facilitate communication with remote devices, enabling data exchange over long distances.

The process of converting serial bits (a stream of data) into blocks of bytes and vice versa, often including error correction.

This layer interacts with devices as logical resources, using device identifiers and simple commands. It handles general I/O functions for user processes.

A technique used in I/O operations that involves the transfer of data between memory and an I/O device without CPU intervention. This is a dedicated hardware module that manages the transfer.

A key characteristic of DMA that specifies the starting address in memory for reading or writing data. It is stored in the DMA module's address register.

The number of words to be read from or written to memory during a DMA transfer. It's communicated to the DMA module and stored in its data count register.

The process of allocating resources to different tasks within a system, including assigning CPU time, memory, and peripheral device access.

A method of transferring data between two buffers while one is being used and the other is being filled/emptied.

A scheduling policy that prioritizes the oldest request in the queue, ensuring fairness, but potentially leading to poor performance with many competing processes.

A scheduling policy that prioritizes the most recent request in the queue, often used in transaction processing systems.

A disk scheduling policy that divides the disk request queue into sub-queues and processes each sub-queue using SCAN, improving efficiency by reducing the maximum delay.

A disk scheduling policy that uses two sub-queues, placing new requests in the empty sub-queue during a scan, balancing efficiency and fairness.

A disk scheduling policy in which the disk arm moves in one direction, processing all requests encountered until reaching the end, then reverses and repeats the process.

A disk scheduling policy that prioritizes requests based on the proximity of the disk arm to the requested sector, minimizing the time spent moving the arm.

A disk scheduling policy that prioritizes requests based on the distance from the current position of the disk arm, prioritizing requests closer to the current position.

A scheduling policy where the disk arm starts at one end of the disk and moves to the other end, processing every request along the way, before returning to the starting point.

A scheduling policy where jobs are prioritized based on their importance, allowing short jobs to be processed quickly. This results in good response time for shorter tasks but longer jobs may experience significant delays.

A disk scheduling algorithm where requests are processed in the order they arrive, regardless of their location on the disk. This can lead to excessive head movement and slow performance, especially with a high workload.

A disk scheduling algorithm that prioritizes requests based on their proximity to the current disk head position. This minimizes head movement, improving performance by reducing wasted time.

A disk scheduling algorithm that prioritizes requests based on their order in a circular track, aiming to balance head movement across the disk. This helps to prevent starvation of requests located further from the current head position.

A disk scheduling algorithm where requests are processed in a predetermined order, typically starting from the beginning of the disk and moving sequentially to the end. This can improve performance by minimizing head movement and ensuring fairness for all requests.

A disk scheduling algorithm that prioritizes requests based on their estimated completion time, aiming to optimize disk utilization and minimize overall completion time for all requests.

A standardized scheme for multiple-disk database design, offering different levels (0 to 6) with variations in data distribution, redundancy, and performance characteristics.

A feature in RAID systems where data is distributed across multiple disks, improving performance by allowing parallel access to data.

RAID level where data is striped across multiple disks, providing fast read speeds but no fault tolerance.

RAID level where data is striped across multiple disks and parity information is stored on a separate disk, providing both speed and fault tolerance.

A temporary storage area used to speed up data access by holding frequently used data.

A type of cache specifically designed for disk data, improving disk read and write performance by storing frequently accessed disk sectors in memory.

The principle that accessing data that is physically close to previously accessed data is more efficient.

A technique that combines multiple physical disks into a single logical unit, offering improved performance and fault tolerance.