The I/O interface required to connect an I/O device to the bus consists of an address decoder, registers, and control circuits.

Address Decoder:
- An address decoder is responsible for decoding the address signals from the bus and selecting the specific I/O device to communicate with.
- It determines which device is being addressed by comparing the address signals with the device's address range.
- The address decoder enables the I/O device to respond only when its address is being accessed on the bus.

Registers:
- Registers are used to store data and control information exchanged between the I/O device and the computer system.
- They act as temporary storage locations for transmitting data between the I/O device and the computer's memory or processor.
- For input operations, data from the I/O device is stored in the registers before being transferred to the memory.
- For output operations, data from memory is first transferred to the registers before being sent to the I/O device.

Control Circuits:
- Control circuits are responsible for managing the overall operation of the I/O device.
- They control the timing and sequencing of data transfers between the I/O device and the computer system.
- Control circuits generate control signals that instruct the I/O device on when to perform specific operations, such as reading or writing data.
- These signals are synchronized with the computer system's clock to ensure proper coordination.

Why address decoder, registers, and control circuits are required?
- The address decoder is necessary to enable communication between the specific I/O device and the computer system.
- Registers are needed to temporarily store data during input and output operations.
- Control circuits are essential for managing the overall operation and timing of the I/O device.

Overall, the combination of address decoder, registers, and control circuits forms the necessary I/O interface that allows the I/O device to connect and communicate with the computer system via the bus.