1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
|
// This file is part of www.nand2tetris.org
// and the book "The Elements of Computing Systems"
// by Nisan and Schocken, MIT Press.
// File name: projects/demo/Xor.hdl
/**
* Exclusive-or gate: true if either a is true and b is false, or
* a is false and b is true; false otherwise.
* QUESTION: how can the simulator execute this program properly without
* HDL implementations of the underlying Not, And, and Or chip-parts?
* Answer: since the demo folder contains no Not.hdl, And.hdl and Or.hdl
* files, the simulator reverts to using their built-in implementations.
*/
CHIP Xor {
IN a, b;
OUT out;
PARTS:
Not (in=a, out=nota);
Not (in=b, out=notb);
And (a=a, b=notb, out=x);
And (a=nota, b=b, out=y);
Or (a=x, b=y, out=out);
}
|
