http://www.learningaboutelectronics.com/Articles/D-flip-flop...

Agreed on the 'preemtive multitasking' bit, but that has little to do with this subject. And it is kind of embedded in the name, you need something to do the pre-empting which by definition has to come from outside.

But building a functional computer with just NAND gates is absolutely possible, even if there are better ways, just like you could use Brainfuck or combinators to do meaningful computation. The whole idea of the course is not to give some kind of purist model for computation but to show that the essence of a computer can be boiled down to some very simple building blocks. So the title of the course is misleading only if you want to pick nits. Course titles are made to attract students and to give broad cover to what the course is all about, not to satisfy language purists.

You can use NAND to make NOT.

The fact that nMOS switches off quicker is why the most common form of dynamic logic (as opposed to static logic) implements, in effect, the bottom half of the CMOS in nMOS and the upper half using a capacitor; which holds the charge and hence pull up for the length of the clock cycle (which is why dynamic logic CPUs can't be single stepped in hardware, the clock speed is too low to hold a charge).

The Apollo computer, which used bipolar instead of CMOS, indeed did use all NOR gates:

http://klabs.org/history/ech/agc_schematics/

http://mikestewart.hcoop.net/2015/09/21/interpreting-the-sch...

This doesn't really hold in today's world of silicon prints, but at the start I think it was price that drove the decision.