The value of carry flag (CY) and auxiliary carry (AC) flag respectively will be for given instructions of an 8085 microprocessor.

Consider the following instructions of an 8085 microprocessor
MVI D, 6 EH
MVI E, 5 DH
MOV A, D
ADD E
If above sequence of instructions are executed, then the value of carry flag (CY) and auxiliary carry (AC) flag respectively will be

(A) CY = 0, AC = 0
(B) CY = 0, AC = 1
(C) CY = 1, AC = 1
(D) CY = 1, AC = 0

1Comment
shivani @shivani1234
24 Jul 2017 10:19 pm
  • lets solve this question by analysing statements
    MVI D, 6 EH //D has got contents as 6EH which can be written as 0110 1110
    MVI E, 5 DH //E has got contents as 5DH which can be written as 0101 1101
    MOV A, D//move contents of D from D to A
    ADD E// add contents of A and E
  •    0110 1110
    + 0101 1101
      =1100 1011
  • AC(Auxilliary Carry is carry from lowerto higher nibble) while CY(Carry is out of MSB only),
    so CY=0, and AC=1