a computer machine instruction is fetched and executed , the machine instruction having a signed field value wherein the signed field value comprises contiguous bit positions 1 - n consisting of a contiguous most significant value contiguous with a contiguous embedded sign field , the embedded sign field contiguous with a contiguous least significant value . preferably , the sign field is one bit , the contiguous most significant value comprises bit position n and the least significant value comprises bit position 1 wherein n is the least significant bit of the most significant value .