Final answer:
Disk drives, USB keys, sensors, and controllers are examples of external I/O devices, which interact with the computer system. External hard drives encode information magnetically for quick data storage and retrieval, crucial for digital device development.
Step-by-step explanation:
Disk drives, USB keys, sensors, and controllers are examples of external I/O devices. These devices allow a computer system to interact with the outside world. Input devices, such as sensors and keyboards, send data to the computer, while output devices, like monitors and printers, receive data from the computer. In the case of the external hard drive, it utilizes magnetic fields to encode and retrieve information swiftly, contributing to the advancement of digital devices. This ability has been a key idea since the inception of digital storage technologies.
Disk drives store and retrieve data, USB keys allow for portable storage and transfer, sensors capture input from the environment, and controllers manage and regulate external devices.