Re: Simplest possible ALU implementation using only previously-defined chips?

Posted by SirGouki on
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Simplest-possible-ALU-implementation-using-only-previously-defined-chips-tp4034757p4034979.html

I know this is outside the scope of nand2tetris, but you can easily implement AND with 2 transistors, and not with 1 (making nand 3 transistors since it is not(and)).

Is there a reason why nand would use 4 transistors instead of 3?

I've realised, by looking it up, that you can also implement nand itself with 2 transistors, but I suspect this circuit diagram to be incorrect as its using the same transistors in the same direction:

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fi.stack.imgur.com%2F2GSIm.png&f=1&nofb=1

I'm making a guess the resistor placement is doing something I'm not accounting for as it's been a long time since I've had the stuff to mess with my breadboard (most of my electronics prototyping stuff was stolen by a roommate)