c51程序无反应

请各位大大赐教。这是我们微机课程的单片机代码，用单片机向外发指令码，指令码很少所以就直接置入地址了。程序在keil上仿真的时候通过模拟串口输出没有问题，但是烧到开发板上后串口输出端完全没有反应，已经排除开发板的故障。请各位大大赐教！

org 0000h

ljmp main

org 0200h

main:

mov TMOD,#20h

mov r0,#40h

mov 60h,#30h ; 0

mov 61h,#31h ; 1

mov 62h,#35h ; 5

mov 63h,#0dh ; 0d and 0a are stop bits

mov 64h,#0ah

mov 65h,#41h ; A

mov 66h,#54h ; T

mov 67h,#5Ah ; Z

mov sp,#60h

mov scon,#50H

mov pcon,#80h

mov tl1,#0fah

mov th1,#0fah

setb tr1

mov p3,#11111111b

choose:

mov r0,#40h

mov 60h,#30h ; 0

mov 61h,#31h ; 1

mov 62h,#35h ; 5

mov 63h,#0dh ; 0d and 0a are stop bits

mov 64h,#0ah

mov 65h,#41h ; A

mov 66h,#54h ; T

mov 67h,#5Ah ; Z

jnb p3.0,jump1

jump1:

jnb p3.4,fuwei

jnb p3.5,again

sjmp choose

fuwei:

mov a,65h

mov sbuf,a

jnb ti,$

clr ti

mov a,66h

mov sbuf,a

jnb ti,$

clr ti

mov a,67h

mov sbuf,a

jnb ti,$

clr ti

mov a,63h

mov sbuf,a

jnb ti,$

clr ti

mov a,64h

mov sbuf,a

jnb ti,$

clr ti

againfuwei:jnb ri,$

clr ri

mov a,sbuf

cjne a,#0Ah,againfuwei

ljmp choose

again:

mov a,60h

mov sbuf,a

jnb ti,$

clr ti

mov a,61h

mov sbuf,a

jnb ti,$

clr ti

mov a,60h

mov sbuf,a

jnb ti,$

clr ti

mov a,62h

mov sbuf,a

jnb ti,$

clr ti

mov a,63h

mov sbuf,a

jnb ti,$

clr ti

mov a,64h

mov sbuf,a

jnb ti,$

clr ti

again1:jnb ri,$

clr ri

mov a,sbuf

mov @r0,a

inc r0

cjne a,#0Ah,again1

mov a,46h

cjne A,#40h,L1

L1:jc L2

clr c

subb a,#37h

mov 46h,a

second:

mov a,47h

cjne A,#40h,L3

L3:jc L4

clr c

subb a,#37h

mov 47h,a

third:

mov a,49h

cjne A,#40h,L5

L5:jc L6

clr c

subb a,#37h

mov 49h,a

fourth:

mov a,4Ah

cjne A,#40h,L7

L7:jc L8

clr c

subb a,#37h

mov 4Ah,a

ljmp paixu

L2:clr c

subb a,#30h

mov 46h,a

ljmp second

L4:clr c

subb a,#30h

mov 47h,a

ljmp third

L6:clr c

subb a,#30h

mov 49h,a

ljmp fourth

L8:clr c

subb a,#30h

mov 4Ah,a

ljmp paixu

paixu:

clr c

mov a,46h

rlc a

rlc a

rlc a

rlc a

add a,47h

mov 46h,a; gaowei

clr c

mov a,49h

rlc a

rlc a

rlc a

rlc a

add a,4Ah

mov 47h,a; diwei

clr c

mov a,46h

rrc a

mov 50h,a

mov a,47h

rrc a

mov 51h,a

clr c

mov a,50h

rrc a

mov 50h,a

mov a,51h

rrc a

mov 51h,a

mov th1,50h        ;high

mov tl1,51h

MOV R0, TH1

     MOV R1, TL1

     CALL HEX2BCD      ;

HEX2BCD:

     CLR A

     MOV R2, A            ;???

     MOV R3, A

     MOV R4, A

     MOV R5, #16          ;???????

LOOP:

     CLR C

     MOV A,   R1           ;?????????????Cy

     RLC A

     MOV R1, A

     MOV A,   R0

     RLC A

     MOV R0, A

     MOV A,   R4           ;??BCD????

     ADDC A,   R4           ;?????????,???????

     DA   A                 ;?????,??BCD?

     MOV R4, A

     MOV A,   R3

     ADDC A,   R3

     DA   A

     MOV R3, A

     MOV A,   R2

     ADDC A,   R2

     MOV R2, A

     DJNZ R5, LOOP        ;???????

mov 44h,r4 ;shi ge

mov 43h,r3 ;qian bai

mov 42h,r2 ;wan

mov 41h,r1

mov 40h,r0

  ljmp choose

end