---
title: "Explain I/O interface"
subject: "Computer Organization and Architecture"
chapter: 7
key: "semester_5/computer_organization_and_architecture:io-interface-role"
source: https://www.bctengineer.com/q/semester_5/computer_organization_and_architecture/io-interface-role
site: BCT Engineering
---

# Explain I/O interface

Computer Organization and Architecture · Chapter 7: Input-Output Organization

- Asked in: 2074 Chaitra, 2 marks; 2071 Chaitra, 4 marks; 2068 Baisakh (old course), 6 marks (asked 3 times)
- Video: [I/O Interface in Computer Organization](https://www.youtube.com/watch?v=PM728r4oGcE) — Gate Smashers
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/computer_organization_and_architecture/io-interface-role
- Whole chapter: https://www.bctengineer.com/md/semester_5/computer_organization_and_architecture/chapter-7

## Question

Explain I/O interface.

## Short answer

An I/O interface sits between the system bus and a peripheral, handling signal conversion, speed matching via buffers, control/timing, device selection, status reporting, error detection, and interrupt generation. It decodes addresses and converts data formats.

## Answer

An I/O interface is the hardware between the CPU/system bus and a peripheral device. It converts the signals and data format of the device into those of the computer and controls the transfer.

#### Functions of an I/O interface
- **Speed matching:** a buffer holds data because the device is much slower than the CPU.
- **Data format and code conversion:** serial to parallel and parallel to serial, and voltage level or code differences.
- **Control and timing:** issues the device commands and synchronises the transfer using status flags and handshaking.
- **Device selection:** decodes the address to find which device the CPU wants.
- **Status reporting:** tells the CPU if the device is ready, busy or in error.
- **Error detection:** detects errors such as parity errors.
- **Interrupt generation:** informs the CPU when the device is ready.

```text
  CPU / system bus                       Peripheral
  +---------+     +----------------+     +--------+
  | Address |---->| Interface      |---->| Device |
  | Data    |<--->| Data reg       |<--->|        |
  | Control |---->| Status/Control |<----|        |
  +---------+     +----------------+     +--------+
```

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. I/O interface is?
   A. Hardware between CPU/bus and peripheral converting signals and format
   B. A cache
   C. Memory
   D. Program
   Answer: A. It also controls transfer. (Key point: Definition)

2. How does it handle slow devices?
   A. Buffer
   B. Faster clock
   C. Ignores
   D. Cache
   Answer: A. Buffer holds data. (Key point: Speed matching)

3. Which conversion?
   A. Serial to parallel and back
   B. Decimal to binary only
   C. None
   D. Text to image
   Answer: A. Also code and voltage. (Key point: Format conversion)

4. How is device chosen?
   A. Decoding the address
   B. Random
   C. Tag
   D. Dirty bit
   Answer: A. Address decode. (Key point: Device selection)