Host device and input-output system

An input-output system comprising:

• multiple guest devices, wherein each guest device of the multiple guest devices, in operation, displays an image in a guest display region of the guest device;
• and
• a host device that, in operation, displays at least two images in a host display region of a host device, and communicates with each of the multiple guest devices,
• wherein:
• the host device, in operation, acquires a first indicated position in the host display region of the host device and transmits, to each of the multiple guest devices, a relative coordinate value that is obtained by normalizing a first coordinate value representing the first indicated position in the host display region of the host device, and
• each guest device of the multiple guest devices, in operation, calculates a second coordinate value representing a second indicated position in the guest display region of the guest device, using display region information relating to the guest display region of the guest device to convert the relative coordinate value received from the host device.