Faster. Ever faster.
There are around 180 devices on the submarine that the Opto hardware needed to communicate with.
Since every signal could not have its own physical wire, all the devices used a serial protocol. Each device had an address and a set of registers that could take commands or report their status back to the control program.
The interior of the pilot sphere remained at atmospheric pressure (around 14 psi), so there was no decompression requirement for the pilot. The outside of the sphere however took the full brunt of the mass of all the water above it. At the Mariana Trench, that was around 16,000 psi.
Serial data, power, and video camera feeds went in and out of the sub via very (very) special connectors called penetrator ports, electrical and fiber optic cables that had been cast in glass.