The original series was shot and printed on 35mm film (like a feature). 16mm reduction negatives and prints were generated for
the series distribution in syndication in the 1970's and 80's. (To my knowledge, no new 16mm prints have been struck since 1989?)
In the late 1980's, Fox transfered the best original 35mm fine grain B&W master positives and CRIs (color reversal intermediates)
to 1" (one inch) videotape. It was these elements that were used for the Columbia House VHS tapes and the Japanese laser discs.