Input Output Organization in Computer Organization

• The input-output (I/O) organization is an important computer component that manages data transfer between the computer's central processing unit (CPU) and peripheral devices.
• This organization is crucial for the seamless flow of data in a computer system, and it involves various components and techniques.

What are Peripheral Devices?

• Peripheral devices are hardware components attached to a computer that extend its capabilities beyond simple computation.
• They serve as the bridge between the physical world and the digital realm, allowing users to interact with the computer and vice versa.

Examples

• Keyboard: A common input peripheral is used to enter text and commands.
• Mouse: An input device that provides a pointing interface.
• Monitor An output device that displays visual information.
• Printer: An output device used to produce hard copies of documents.

Input Output Interfaces

• Input-Output Interfaces are how the CPU communicates with peripheral devices.
• These interfaces define the protocol and data input required for data exchange.

Examples

Universal Serial Bus (USB)

HDMI

Ethernet

Asynchronous Data Transfer

• Asynchronous data transfer is a way to transfer data between the CPU and the device without needing to be completely synchronized.
• This flexibility ensures that data can be transferred at varying speeds.

Example

• Consider a user typing on a keyboard; the data entered is sent to the CPU asynchronously.
• The CPU processes the data at its speed, which may not perfectly align with the user's typing speed.

Modes of Transfer

• Modes of transfer refer to the different ways data can be moved between the CPU and peripheral devices.
• There are various modes, such as program-controlled I/O, interrupt-driven I/O, and DMA.

Example

• In program-controlled I/O, the CPU explicitly manages data transfer, often used in simple devices like serial ports.
• In contrast, interrupt-driven I/O allows the CPU to handle data transfer when a peripheral device generates an interrupt request.

Priority Interrupt

• Priority interrupt is a mechanism that allows the CPU to handle multiple interrupt requests from different devices with varying priorities.
• It ensures that higher-priority tasks are processed before lower-priority ones.

Example

• Imagine a computer with multiple peripherals requesting attention simultaneously.
• The CPU uses priority levels to determine which device's request to process first.
• Critical devices like emergency stop buttons may be prioritized over non-critical devices like a printer.

Direct Memory Access (DMA)

• Direct Memory Access (DMA) is a technique that allows peripheral devices to access the computer's memory directly without CPU intervention.
• This significantly speeds up data transfer and offloads the CPU from handling I/O operations.

Example

Conclusion