Well, it's still like this. One problem at a time.
1. In co-operative multitasking, the computer oompaloompas work on the calculator one at a time and let their boss know when the calculator is free to use. The working oompaloompa can also decide to take a break, leave their work on the desk and let someone else do their work while they do not need the calculator.
2. In pre-emptive multitasking the boss tells an oompaloompa to start working. The oompaloompa is forced to work until their work is done or the boss decides to hit it with a stick and put some other oompaloompa to work. Poor oompaloompa does not know how much time he has and when he gets hit, he has to drop his work immediately.
3. In symmetric multiprocessing the oompaloompas have multipla calculators but only one table and a filing cabinet. The oompaloompas have to coordinate together how to organize their work, so they don't scribble on each others notes, while they take turns on the calculator. The boss is usually in charge of the desk space and the filing cabinet.
4. In distributed vector... I think I write something about hungry philosopher oompaloompas now! They are not good with forks. Or something... Anyway, what was I speaking of? Oh yeah, I'm thirsty. Mmmm... Sluuuuuurmmm...