hello every body!

well i have attached 4 phase stepper motor with the ports of 8155's PA0-PA3 that is interfaced with 8051 and being interrupted with key pad.
If i press A from key pad then i will interrupt the MPU 8051 and display it on LCD 47780 and stepper motor should be move in clock wise direction.
If i press B then it will display on LCD 47780 and stepper motor should be move in back ward direction.
If i press C then it will display on LCD 47780 and stepper motor should be stop.

please help me because i have made the software of it but it doesn't work.
please tell me and give me the source code of it

source code should be in assembly language

from
sumair