If R1 contains xFFFF and R2 contains x0000 then what are the condition code values after the following instruction is executed?0101 011 001 0 00 010A.) N is B.) Z is C.) P is D.) Is it possible for more than one condition code in LC-3 to be set to 1 at the same time?
Question
If R1 contains xFFFF and R2 contains x0000 then what are the condition code values after the following instruction is executed?0101 011 001 0 00 010A.) N is B.) Z is C.) P is D.) Is it possible for more than one condition code in LC-3 to be set to 1 at the same time?
Solution
The instruction given is an ADD instruction in LC-3 assembly language. The operation is R1 + R2. Given that R1 contains xFFFF (which is -1 in two's complement) and R2 contains x0000 (which is 0), the result of the operation is -1.
The condition codes are set based on the result of the operation:
A.) N (negative) is set if the result is negative. In this case, the result is -1, so N is 1.
B.) Z (zero) is set if the result is zero. In this case, the result is not zero, so Z is 0.
C.) P (positive) is set if the result is positive. In this case, the result is not positive, so P is 0.
D.) In LC-3, only one condition code can be set at a time. The condition codes are mutually exclusive. This means that if the result of an operation is negative, only the N condition code will be set. If the result is zero, only the Z condition code will be set. If the result is positive, only the P condition code will be set. So, it is not possible for more than one condition code in LC-3 to be set to 1 at the same time.
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