This flag is set whenever the result of a signed number operation is too large, causing the high-order bit to overflow into the sign bit. In general, the carry flag is used to detect errors in unsigned arithmetic operations. The overflow flag is only used to detect errors in signed arithmetic operations.

How is overflow flag set?

The overflow flag is thus set when the most significant bit (here considered the sign bit) is changed by adding two numbers with the same sign (or subtracting two numbers with opposite signs). ... Internally, the overflow flag is usually generated by an exclusive or of the internal carry into and out of the sign bit.

What is the purpose of overflow flag in 8051?

OV (overflow flag):

This flag is set whenever the result of a signed number operation is too large causing the high order bit to overflow into the sign bit. the carry flag is used to detect error in unsigned arithmetic operations. the overflow flag is only used to detect error in signed arithmetic operations.