Pretty much all dramatic American TV shows were shot on film (at 24 fps) before the digital camera era. It's why so many old shows (ex. Star Trek TNG) are now available as HD remasters, they simply go back and rescan the film.
It's more complicated in other countries (the BBC liked to shoot on video a lot) but it was standard practice in the States.
It took far more than simply rescanning the film to get the TNG remasters as all the visual effects were only rendered and composed at broadcast resolutions (and framerates). They had to essentially recreate all of that, which is why we haven't gotten the same remasters for the less popular Deep Space Nine and Voyager series.
From what I have see most series of that era were edited in NTSC after converting the original film material.
It's more complicated in other countries (the BBC liked to shoot on video a lot) but it was standard practice in the States.