Physical devices and communication interfaces
I/O hardware encompasses the physical devices and communication interfaces that allow computers to interact with the external world. Computer systems support a wide variety of I/O devices including storage devices (hard drives, SSDs, optical drives), display devices (monitors, graphics cards), input devices (keyboards, mice, touchscreens), network interfaces (Ethernet cards, Wi-Fi adapters), and specialized devices (sensors, actuators, scientific instruments). These devices connect to the computer system through various interfaces and buses such as PCI Express (high-speed expansion bus), USB (Universal Serial Bus for peripherals), SATA (Serial ATA for storage devices), Thunderbolt (high-speed interface), and legacy interfaces like Parallel ATA and Serial ports. Each device is controlled by a device controller that contains registers for command, status, and data transfer. The operating system communicates with these controllers through device drivers that translate high-level commands into device-specific operations. Understanding I/O hardware is essential for system designers, device driver developers, and hardware engineers to create efficient and compatible systems that can effectively utilize the capabilities of modern peripheral devices.