Analog passthrough

Analog passthrough is a feature found on some digital-to-analog television converter boxes. Boxes without the analog passthrough feature only allow older, analog-only TVs to view digital TV. Those with analog passthrough allow both digital and analog television to be viewed on older TVs.

Before digital television, passthrough originally existed in VCRs (and later PVRs and DVDRs) that connected to a TV set using RF connector, allowing the TV antenna or cable TV signal to be switched to pass through the VCR, or have VCR output added as an extra channel.