The 3-to-1 ZV switch is a companion chip to the PCI1220/1221 PC Card controllers; however, it can be used in other applications where multiple ZV sources require external buffering. The ZV switch is a 3:1 multiplexer for the 23 pins defined in the PCMCIA zoomed video interface. The ZV interface includes both the video and audio data as defined by the Zoomed Video Specification. The three ZV source interfaces are referred to as A, B, and C. ZV sources A and B are intended for use with the PCI1220/1221 PC Card zoom video outputs. The third source, C, may be from a variety of external ZV sources.