I can remember it, I think in setups where the TV signal was passed through a VCR (so it could be recorded) and then into the TV. If the VCR detected there was

I can remember it, I think in setups where the TV signal was passed through a VCR (so it could be recorded) and then into the TV. If the VCR detected there was no useful signal it would output a blue image instead of static. Just showing raw static was much more common though.