True multi-tasking is 1 processor running various tasks in their own time slot. We have gotten used to Multi-processing with cheaper and cheaper silicon and the resulting ability to pack more in less space. But much of it still boils down to one processor doing several things in sequence, and doing it so fast that it looks like many things are happening in real time.
This has been going on for many years. My first multitaking system was an Allen-Bradley PLC (programmable logic controller) which was able to control various parts of a machine, asynchronously. It ran a tight control loop that executed 535 time a second. Close enough to be called real time. Read an encoder through 12 digital inputs, Had about 48 switch inputs for the various parts of the machine, approx 24 outputs for various motors and solenoids. Had 4 separate subsystems all running their own control sequence at the same time.
It is interesting that with Arduino and such we are just going back to the early days of industrial PLC control. 1 processor managing some I/O and making things do their stuff based on some logic and some inputs.