Re: 3 engine rooms in the TOS Enterprise's engineering hull?
That screen is when Chekov is asked to look at helm and navigation control so it is unlikely warp engines and reactors.
Not necessarily as they are trying to cut off power
from the corresponding automatic circuit relay and switch to manual.
SPOCK: There is one possibility. The automatic helm navigation circuit relays might be disrupted from engineering level three.
SPOCK [OC]: Examine the H two seven nine elements, also the G nine five systems.
CHEKOV: Sir, G nine five system appears dead. All indicators are dark.
SPOCK: Thank you, Ensign. SPOCK: It appears, Captain, we've been doing what used to be called pursuing a wild goose. M-5 has rerouted helm and navigational controls, bypassing this primary
(i.e. power) system.
"The first duty of every Starfleet officer is to the truth" Jean-Luc Picard
"We can't solve problems by using the same kind of thinking we used when we created them." Albert Einstein