Status Register The status register tells the overflow status of the 8087 coprocessor. It is a 16-bit register. It is accessed by executing the FSTSW instruction. This instruction stores the content of the status register in memory. Once the status is stored in memory the bit positions of the status register can be examined. Busy: It indicates that the coprocessor is busy executing the task. Condition codes ( C0-C3 ): They indicate various conditions about the coprocessor. Top of Stack : It indicates a register as the top of the stack out of the eight stack registers. Exception Flat: It is set if any of the exception flag bits ( SF, PR, UF, OF, ZD, ZD, IO) are set. Stack Faul t : It is not available in 8087. It is active only in 80387 and above. Precision : It indicates that the result has exceeded the selected precision. Underflow : It tells if the result is too small to fit in a register. Overflow: It tells if the result is too large to fit in a re...