Descibe 8085 interfacing of stepper motor to rotate it through 90 degree using 8255?

Unipolar full step Stepper motor: _ _

INPUT SEQUENCE: X Y X Y

1 1 0 0

0 1 1 0

0 0 1 1

1 0 0 1

8255 CONTROL Word: 1 0 0 0 0 0 0 0 =80H

PROGRAM:

MVI A, 80

OUT port B

START MVI A, FC

OUT port A

CALL DELAY

MVI A, F6

OUT port A

CALL DELAY

MVI A, F3

OUT port A

CALL DELAY

MVI A, F9

OUT port A

JMP START

DELAY LXI D, 0003

CALL DELAY

RET