Observations onSigned Integers II
The same bit pattern may be interpreted as either signed or unsigned. We say N is a signed integer if, when we interpret N, we interpret all bit patterns with the sign bit set as negative numbers.
If N is a signed integer, then its bit pattern is to be read as signed, and the leftmost (top) bit is known as the sign bit. If N is signed and the sign bit is set, the bit pattern will be interpreted as a negative number.
Note: If the sign bit is zero, the bit pattern has the same numeric value whether interpreted as signed or unsigned.
If the number is a signed number, zero is positive (the sign bit is not set).