Interface circuits

• An I/O interface consists of the circuitry required to connect an input/ output device to a computer system.

• On one side of the interface have bus signals for address, data and control.

• On the other hand data path with its associated controls to transfer data between the interface and the input/ output device.

• This side is called a port.

• It can be classified as

– Serial port

– Parallel port

Parallel Port• It transfers data simultaneously to (or) from the device.

• It uses multiple pin connector.

• Circuit is simple.

Serial port1. It transmits and receives data one bit at a time.

2. For long distance, it is convenient and cost effective.

1. I/O interface1. It provides a storage buffer for atleast one word of data.

2. Contains status flags that can be accessed by the processor to determine whether the buffer is full (or) empty.

3. Address decoding circuitry to determine when it is being addressed by the processor.

4. Performs any format conversion that may be necessary to transfer data between the bus and the input/ output device such as parallel – serial conversion in the case of a serial port.