Programmed I/O
Programmed I/O (PIO) is a method of data transfer between a computer's CPU and peripheral devices, where the CPU directly controls the I/O operations by executing instructions to read from or write to I/O ports. It involves the CPU polling device status registers to check for data readiness, making it a simple but inefficient approach for high-speed data transfers. This method is often contrasted with interrupt-driven I/O or direct memory access (DMA), which offload work from the CPU.
Developers should learn about Programmed I/O when working on low-level systems programming, embedded systems, or operating system development, as it provides foundational understanding of how CPUs interact with hardware. It is useful in scenarios where simplicity and direct control are prioritized over performance, such as in basic microcontroller applications or legacy systems. However, for modern high-performance computing, alternatives like DMA are preferred to avoid CPU bottlenecks.