Type 0 Tube Transfers
There is an established protocol for data transfers across the Tube. This is necessary because each separate processor can only address its own memory space. The example here shows how to retrieve data from a specified location in the second processor.
The first thing to do is check whether the second processor is active, and exit if not, as this isn't going to work without the Tube.
After that, the Tube transfer can be set up. This involves claiming the Tube, that is, gaining exclusive control of the Tube for the duration of the transfer, then initiating one of 7 types of transfer, then transferring the data, and finally releasing the Tube for use by other processors.
