An input/output apparatus is connected to a plurality of host computers via a network and executes both a scanning function and a printing function. The apparatus includes a portion that generates image data from data input from a first one of the host computers and prints the generated image data by executing the printing function, and further includes an output device that scans image data by executing the scanning function and outputs the scanned image data to a second one of the host computers in response to a request command. As a result, the input/output apparatus may operate in coordination with a plurality of personal computers by using the network to transfer image data therebetween.