Flags Register:
Flags Register The ALU influences a number of flip flops called flags which store information related to the results of arithmetic and logical operations. Taken together this flags constitute a flag register. The Flag register is a Special Purpose Register and is completely different from the other registers in a microprocessor. Flag register is an 8-bit register accessible to the user through instruction. Each bit in the flag register has a specific function.The other 3 are left vacant and are in the future Intel versions. Therefore, 8085 has five flags - Sign flag, Zero flag, Auxillary carry flag, Parity flag and the Carry flag. Only 5 bits out of 8 bits are used as shown below: D7 D6 D5 D4 D3 D2 D1 D0 S Z X AC X P X CY The three crossed bit are redundant bits and not used. They can be either ‘0’ or ‘1’ but normally they are forced to be zero. The o...