I worked for RCA Smirnoff Labs back in the day, mid 1980's. The explanation I heard was that the 25 inch CRT "tall" configuration had nearly the same footprint as the 19 inch CRT wide configuration. That a consumer could have a bigger screen atop the same piece of furniture. IIRC, the CTC121 was RCA's first "tall" set. And it had a 2 line comb filter.
I don't remember if anyone there said RCA "invented" the "tall" set or not. It wouldn't be a real patentable invention anyway.
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