6.1.1 The user interface
An interface to a washing machine does not need to be like the interface to a personal computer (a user interface is a display/control panel that enables the user to control a machine or interact with a program). It is specific to the task of washing laundry, which involves two things:
displaying the choices that relate to washing laundry (such as type of laundry to be washed, water temperature, and spin speed);
displaying some indication of the state of the machine and/or the programme selected. On the machine control panel shown in Figure 6.1, the displays on the right show:
the time remaining in the current wash programme;
a series of lights showing which parts of the programme (wash, rinse and spin) remain to be done.
This machine also uses an audible signal (a periodic beep) to tell the user when the washing cycle is complete.