I have just aquired a P3 printer its silver in colour so appears to be manufactured before 86. It appears not to compatable with the S4, when plugged in to the S4 printer port the S4 beeps continually and the pointer on the S4( if that is what it is called) goes to the left. If not compatable can it be easily made compatible or what am I doing wrong?

Make sure that your S4 timer has a power supply attached to it. The P3 printer draws a great deal of power and usually shuts the S4 down and the "END" message appears. Ideally the S4 should have nicad or nimh batteries installed. The little red jumper next to the on/off toggle switch needs to be moved to the outside position so that the batteries will charge. NEVER put alkaline batteries in the timer once the change has been made.