Programmed I/O
Programmed I/O (PIO) is a method of data transfer between a computer's central processing unit (CPU) and peripheral devices, where the CPU directly controls the I/O operations by executing instructions to read from or write to device registers. It involves the CPU polling device status and handling data byte-by-byte or word-by-word, making it simple but CPU-intensive. This approach is commonly used in early or embedded systems where hardware simplicity is prioritized over performance.
Developers should learn Programmed I/O when working on low-level system programming, embedded systems, or legacy hardware where direct CPU control over I/O is necessary, such as in microcontrollers or simple peripherals like keyboards. It is useful for scenarios requiring precise timing or minimal hardware complexity, but it can lead to high CPU overhead, so it's best suited for low-bandwidth or infrequent I/O tasks.