Re: Last 4 Mulit-way Mulit-bit gates

Posted by WBahn on
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Last-4-Mulit-way-Mulit-bit-gates-tp4033146p4033147.html

The key to the highlighted sentence is that it is referring specifically to cases where a bus is carrying a number. For instance, the output from the ALU after doing an addition operation. So say that the bits on the bus happen to be

0000 0101 1010 1111

Note that the spaces are there just to make things more readable for us humans.

Which of those bits is the least significant and which is the most? That sentence is simply telling you that the left bit is the most significant and the right bit is the least significant. Remember that, as far as the hardware is concerned, these are just sixteen different bits on sixteen different wires, we need to understand how to determine what value that pattern of sixteen bits represents. So number from right to left starting with 0 and ending with 15. Then the weight of a given bit is just 2^(bit position number). You then multiply each bit in the pattern (either a 0 or a 1) by the weight for that position and add up the results.