EXCEPT in TOS, where THERE WAS NO WARP CORE and THERE WAS NO DILITHIUM CHAMBER
The idea of a "warp core" has only been around since 79. I chalk that one up to so called fans not knowing jack about TOS and thinking they do... cough....
Hi, I'm 'jack.' Glad to meetcha.
3rd season had a dilithium chamber in ELAAN OF TROYIUS. Pretty sure they had one in ALTERNATIVE FACTOR as well, but I'll be damned if I try watching two frames of it to check.
TAS had an intermix chamber thingie.
The big forced perspective thing behind the mesh in TOS may not have been CALLED a warp core, but it certainly seemed to serve as a visual reference for (big quote marks around this) THE ENGINE.