Implementing a Signed Greater-Than Comparator

Testing signed integer comparison logic in hardware design

This is a medium-difficulty digital design question that tests your understanding of how CPU flags encode the result of arithmetic operations. It appears frequently in interviews at firms that develop trading infrastructure, market simulators, or low-latency systems where hardware-level reasoning matters.

The question asks you to derive a correct comparison predicate from the flags set by a subtraction instruction. To solve it, you must reason about how signed overflow behaves across the full range of 8-bit two's-complement integers, and recognize which combination of flags (such as the sign bit, zero bit, and overflow bit) reliably indicates the desired comparison outcome. The challenge lies in handling the edge cases where overflow occurs—namely, when the magnitude of the result exceeds what a signed byte can represent.

• Two's-complement representation and sign extension
• Arithmetic overflow and underflow in subtraction
• Flag-based conditional logic in processor instruction sets
• Why naive comparisons fail at boundary values