Thanks, Bruce. That answers my question. And yes, Barbie, I did try all the codes in the online user guide, which were more than the codes in the instructions that came with the Comcast remote. Thanks to both of you for replying.
OK TV is set up for cable for main picture and TV off air for sub picture. All works OK when I use TV remote, but does not respond to comcast remote when set to TV function.. I just wondered whether anyone has gotten the comcast remote to work the PIP