In order to build a Mux4way16 we used the code:
Mux16(a=a, b=c, sel=sel[0], out=ac);
Mux16(a=b, b=d, sel=sel[0], out=bd);
Mux16(a=ac, b=bd, sel=sel[1], out=out);
We removed the file for Mux16 in order for the builtin Mux16 to be used.
See this image:
In the graphic you can see that numbers are in binary. when sel[2] is 01 the output should be b[16]
/**
* 4-way 16-bit multiplexor:
* out = a if sel == 00
* b if sel == 01 <------------------
* c if sel == 10
* d if sel == 11
*/
but it chooses c[16].
It seems that it is reading the sel[2] input backwards.
When you set the format to “binary” (on the top) then we can set sel[2] by bits.
When its 01 it seems to be reading it first the 1 for sel[0] and then the 0 for sel[1].
You can see below that its choosing c for ac and d for ad – the wrong choice - it seems to be using sel[0] to be 1 from the rightmost bit. Then it chooses ac for out using the left bit of 0.
So either the Mux16 is problematic or sel[2] array is being read in backwards.
Locked
