UNSIGNED BINARY CODED DECIMAL:

b7 b6 b5 b4 b3 b2 b1 b0
0  0  0  0  0  0  0  0

value = b0 * 2^0 + b1 * 2^1 + ... + b7 * 2^7

val = 0
b7 b6 b5 b4 b3 b2 b1 b0
0  0  0  0  0  0  0  0

val = 1
b7 b6 b5 b4 b3 b2 b1 b0
0  0  0  0  0  0  0  1

val = 2
b7 b6 b5 b4 b3 b2 b1 b0
0  0  0  0  0  0  1  0

val = 3
b7 b6 b5 b4 b3 b2 b1 b0
0  0  0  0  0  0  1  1

Negative numbers use a twos-complement representation

Implication: 8-bit signed integer [-128, 127]

16-bit signed integer: [-2^15, 2^15 - 1]
                       [-32768, 32767]

16-bit unsigned integer: [0, 2^16-1]