7 Input and Output Free Online FlashCards

What does input/output (I/O) mean?

Input/output (I/O) is the exchange of data between a computer and devices outside its main processor and memory.

How do input and output devices differ?

Input devices send data into the computer; output devices receive data from it.

Can a peripheral act as both input and output?

Some devices, such as storage drives and network adapters, both send data to and receive data from the computer.

What does a device controller do?

A device controller manages a peripheral, handles device-specific tasks, and provides an interface for communicating with the computer.

What are the three common types of controller registers?

Data registers exchange device data; status registers report device conditions; command registers let the CPU request operations.

How does memory-mapped I/O expose device registers?

In memory-mapped I/O, device registers occupy addresses in the memory address space, which the CPU accesses to communicate with the controller.

What is polling in I/O?

Polling is when the CPU repeatedly reads a device’s status register to check whether it needs attention or has completed an operation.

What is a key trade-off of polling?

Polling is straightforward, but checking too often consumes CPU time. It can be useful when the wait is very short or a device needs frequent attention.

How does interrupt-driven I/O coordinate with the CPU?

With interrupt-driven I/O, the CPU starts an operation and continues other work; the controller signals an interrupt when attention is needed or the operation finishes.

What happens when the CPU handles an interrupt?

The processor temporarily saves enough information to resume its current work, runs an interrupt handler, and then continues.

What is one efficiency benefit and one cost of interrupts?

An interrupt avoids constant status checking, but handling many frequent interrupts also consumes processing time.

What does direct memory access (DMA) do?

Direct memory access (DMA) lets a DMA-capable controller move data between a device and main memory without the CPU copying every byte or word.