Computer interfacing is becoming more and more popular in schools as both pupils and staff find it stimulating and fun. The user-port monitor was designed to fill a gap in the equipment provision at our school and should be viewed in that light. There is no provision for inputs so the monitor serves a very limited function. However, if a pupil grasps the fundamental ideas involved for outputting then an understanding of inputting will come more easily. The cost of the unit is in the order of about £3, which compares favourably with commercial units.