The word is interfacing generally (or programming for some) but it's just not commonly used for general users. I’d say this is probably because the activity of focus for general users is in use of the applications, not the computer itself despite being instanced with a computer. Thus a computer is commonly less the user’s object of activity, and more commonly the setting for activity.

Similarly using our homes are an extremely common ‘activity’, yet the object-activities that get special words commonly used are the ones with specific user application.