Programmed I/O Programmed I/O is a technique used to control the flow of data between a computer and external devices like sensors, actuators, and printers....
Programmed I/O is a technique used to control the flow of data between a computer and external devices like sensors, actuators, and printers. Instead of relying solely on predefined hardware interrupts or polling, this method allows the program to actively request and receive data when needed.
This approach offers several advantages:
Efficiency: It reduces unnecessary overhead, eliminating the need to constantly check for device availability.
Flexibility: Programs can be designed to handle various devices and data types with minimal code modifications.
Responsiveness: The program can be instructed to interrupt execution when data is available, ensuring timely responsiveness to changes.
Here are some key elements of programmed I/O:
Device Driver: A program must first establish a connection with the external device through a dedicated driver. This driver acts as an intermediary, managing data transfer and device control.
Buffering: Data is often stored in memory (buffer) before being sent or received. This allows for efficient handling of large amounts of data and reduces communication overhead.
Completion Handler: A designated function is called when data transfer is complete. This handler typically performs data processing or presents the received information to the user.
Examples:
A keyboard scan in a computer is controlled by a program through programmed I/O. The keyboard driver acts as the device driver, and the program uses a buffer to store and send keypresses to the computer.
A temperature sensor connected to a microcontroller uses programmed I/O to report the sensor's reading to the microcontroller's operating system.
A graphical user interface (GUI) on a computer uses programmed I/O to receive and respond to user input from a keyboard or mouse.
By understanding and implementing programmed I/O, developers can create efficient and responsive solutions for interacting with external devices and data sources