difficulty facing in 89c2051 based alarm

[numanali]

hi everyone...my friend give me a task to install a an alarm circuit i his little industry.....he gave me instructions that a circuit should alarm after every 30 minutes,and it must only stops when any worker press the button,and when button is pressed the timer must restart ...every time a button is pressed. ckt should acknowledge the computer (data logging) the time button is pressed..
so i thought to use at89c2051 for this purpose i have made the ckt prototype....but still some problems are there, i have to design a driver ckt to on the alarm.and i dont know how to do data logging on pc...by rs485...

this is the circuit i designed but it didnt run according to program....so modify my prog for other micro controller trainer i have....the program runs fine ....now the modifications i want in my hardware is seven segment display of timer and it wud be better if timer can be set by user inputs through switches... can u guide me what modifications i must do in my circuit..plz help i want to make this thing like professional.

ORG 00H
MOV SP,#60
MOV TMOD,#21H ;TIMER 1 MODE 2, TIMER 0 MODE 1
MOV TH1,#-3 ;9600 BAUD RATE
MOV SCON,#50H ; SERIAL MODE SPECIFIER
PROGR: MOV P1,#00H
MOV P3,#00H
ACALL DELAY
;---------------------------------------
CANB: MOV TMOD,#01H
SETB P1.7 ;BUZZER INDICATOR OFF
SETB P1.4 ;ATTENDANCE INDICATOR OFF
SETB P1.1 ;SYSTEM BUSY INDICATOR OFF
CLR P1.3 ;RELAY OFF
SETB P1.0 ;BUZZER ON
ACALL DELAY
CLR P1.0 ;BUZER OFF

;----------------------------------------
REPEAT: CLR P1.1 ;SYSYTEM BUSY ON
ACALL DELAY30M
SETB P1.1 ;SYSTEM BUSY LED OFF
SETB P1.0 ;BUZZER ON
SETB P1.3 ;RELAY ON
CLR P1.7 ;BUZZER INDIACTOR ON
SETB P1.2 ;MAKE P1.2 INPUT PORT

SWITCH: JNB P1.2,SWITCH
CLR P1.0 ; BUZZER OFF
CLR P1.3 ; RELAY OF
SETB P1.7; BUZZER INDICATOR OFF
;-----------------------------------------------
SERIAL: SETB TR1
MOV DPTR,#MYDATA
SER_1: CLR A
MOVC A,@A+DPTR
JZ REPEAT
ACALL TRANSMIT
INC DPTR
SJMP SER_1

TRANSMIT:
MOV SBUF,A
T_1: JNB TI,T_1
CLR TI
RET

;----------------------------------------
DELAY: MOV R4,#100
DL1: MOV R5,#200
DL2: MOV R6,#200
DL3: DJNZ R6,DL3
DJNZ R5,DL2
DJNZ R4,DL1
RET
;----------------------------------------
DELAY30M:

MAIN: MOV R1,#9
MAIN1: MOV R2,#200
MAIN2: ACALL TIMER
DJNZ R2,MAIN2
DJNZ R1,MAIN1
RET
TIMER:
BACK: MOV TH0,#4BH ; FOR 50MS
MOV TL0,#0FDH
SETB TR0
TIM: JNB TF0,TIM
CLR TR0
CLR TF0
RET

MTDATA : DB 'MACHINE ATTENDED',0
;----------------------------------------

END