A/B pin diode switch with VACD-12 distribution amplifier are used for video all-call applications. Video distribution allows the school to interface with local cable television and deliver topical programs to each classroom, originate local programming (either live or playback via a VCR) and provide to every room in the school. Additionally, emergency or general announcement information can be quickly delivered with both audio and video information to each television in the school. Complete line of products for implementing a video all-call system. These systems provide an integrated solution of allowing one channel to override all other channels on all televisions in a school system. In order to integrate all of these components into a complete all-call system, VACD- 12 distribution amplifier and the AB-800 pin diode switch. These two products are used to distribute the alternate audio/video program to each modulator and processor in the system.