IOControllers

An I/O controller (often written IO controller or input/output controller) is a hardware component that manages communication between a computer system and peripheral devices. It translates high-level bus transactions into device-specific signals and logic, implements protocols, and handles data transfer, error detection, and device status reporting. Typical examples include disk controllers, network interface controllers, USB host controllers, and display controllers.

I/O controllers sit between the CPU/memory subsystem and external hardware. They present a standardized interface to the operating system and device drivers while hiding device complexity. Common interfaces include memory-mapped I/O and port-mapped I/O; controllers often support interrupt signaling and direct memory access (DMA) to move data with minimal CPU intervention.

Controllers vary by functionality and integration. In PCs and servers they may appear as discrete cards or integrated chips on a motherboard (e.g., SATA, NVMe, PCIe host controllers). In embedded systems and microcontrollers, peripheral controllers (UART, SPI, I2C) are built into the same silicon. Modern controllers may include offload capabilities such as TCP/IP checksum processing, encryption, or hardware queue management to improve throughput and reduce latency.

Design considerations include protocol compatibility, throughput, latency, reliability, power consumption, and security. Operating system support is provided via device drivers that configure controllers, manage buffers, and expose device features to applications.