     RRA: (address) =>
         @$addValueToAccumulator @ROR address
 
+    AXS: (address) => # Also known as SBX
+        @registerX = @compareRegisterAndMemory @accumulator & @registerX, address
+
     ###########################################################
     # Instruction helper functions
     ###########################################################

        @registerOperation 0x63, @RRA, @indirectXMode, 1, 1 # 8 cycles (undocumented operation)
        @registerOperation 0x73, @RRA, @indirectYMode, 1, 1 # 8 cycles (undocumented operation)

    registerOperation: (operationCode, instruction, addressingMode, emptyReadCycles, emptyWriteCycles) ->
        @operationsTable[operationCode] =
            instruction: instruction

        result = register - operand
        @carryFlag = result >= 0 # Unsigned comparison (bit 8 is actually the result sign)
        @$updateZeroAndNegativeFlag result # Not a signed comparison
        result & 0xFF

    branchIf: (condition, address) ->
        if condition
