Noob open wheel question

[DanicaFreak]

Back in the early days of F1 with prost and Senna and Piquet.

The turbos. Did the driver have control over his boost? Did the driver only have a certain amount of boost?

I clearly remember in the old days the announcer saying "does he have enough boost to chase so and so down".

 

[rd45usa]

Found this old video from 1988. Around 2:10 explains power knob. I do remember before 1987 they had unlimited boost, in 1987 they mandated popoff valves.