Abstract: A display apparatus: a display screen on which a display drive generates a picture in response to picture information (R,G,B,H.V) from a video source connected via a releasable connector to the display apparatus. User controls adjust the picture generated by the display drive in response to a manual input. Selection controls are included for selecting one of a plurality of sets of control data for communication to the video source in response to a configuration code input via the user controls.

Abstract: Synchronization apparatus comprising a phase-locked loop for generating an output signal and for synchronizing the output signal to an input signal, characterized in that the apparatus comprises a controller for iteratively determining whether the output signal is synchronized to the input signal by the phase-locked loop and adjusting the frequency of the output signal to bring the output signal within the capture range of the phase-locked loop if the output signal is not synchronized to the input signal.

Abstract: An interrupt-driven processor system comprising a processor connected via a plurality of processor input and output lines to a keypad or keyboard. Actuation of one of the keys of the keypad or keyboard generates an interrupt signal on one of the input lines which invokes an interrupt service routine in the processor. A secondary interrupt source can be attached via an interrupt line to each of the input lines with the interrupt service routine being designed to discriminate between an interrupt signal generated by actuation of a key and an interrupt signal generated by a secondary source. Using this technique, further interrupts can be added to an off-the-shelf processor including keypad interrupts without the need for additional interrupt controlling hardware. Furthermore, a custom-built microprocessor can be designed with fewer interrupt pins.