# How to convert Excess 3 to Binary 4-bit?

#### ajprameswari

Joined Oct 13, 2011
3
I need to convert Excess 3 to binary 4-bit and implement it into K-Map and combinational circuit.

What makes me confused is..

Do I need to start the input in Truth Table from -3 and set the output to Don't care?

This is what I meant.

Decimal Excess-3 Binary 4-bit
A B C D W X Y Z
---------------------------------
-3 0 0 0 0 X X X X
-2 0 0 0 1 X X X X
-1 0 0 1 0 X X X X
---------------------------------
0 0 0 1 1 0 0 0 0
1 0 1 0 0 0 0 0 1
2 0 1 0 1 0 0 1 0
3 0 1 1 0 0 0 1 1
4 0 1 1 1 0 1 0 0
5 1 0 0 0 0 1 0 1
6 1 0 0 1 0 1 1 0
7 1 0 1 0 0 1 1 1
8 1 0 1 1 1 0 0 0
9 1 1 0 0 1 0 0 1
10 1 1 0 1 1 0 1 0
11 1 1 1 0 1 0 1 1
12 1 1 1 1 1 1 0 0
---------------------------------
13 X X X X 1 1 0 1
14 X X X X 1 1 1 0
15 X X X X 1 1 1 1

Do I need to set the Outpout of dec(-3,-2, and -1) into (1101, 1110, and 1111) as signed bit for negative?

Any help would really be appreciated.
Thanks

#### Georacer

Joined Nov 25, 2009
5,182
It really depends on the purpose of your circuit, which you have not shared with us.

Is that thread of any help?