汇编程序应用于单片机的串口通信，求高手解答

ORG 0000H
JMP MAIN
ORG 0023H
JMP SINT
ORG 0040
MAIN:
MOV SP,#5FH
MOV TMOD,#20H
MOV SCON,#50H
MOV TH1,#0E8H
MOV TL1,#0E8H
SETB TR1
SETB ES
SETB EA
SJMP $
SINT:
PUSH ACC
PUSH PSW
JNB RI,QUIT
CLR RI
MOV A,SBUF
CJNE A,#0E1H,QUIT
CALL UPDATA
CALL TX16  
QUIT:
POP PSW
POP ACC
RETI
TX16:
MOV R7,#12
MOV R0,#40H
L1:
MOV SBUF,@R0
JNB TI,$
CLR TI
INC R0
DJNZ R7,L1
RET
UPDATA:
MOV R7,#12
MOV R0,#40H
MOV DPTR,#NUM
MOV A,#00H
L2:
MOVC A,@A+DPTR
MOV @R0,A
INC A
INC R0
DJNZ R7,L2
RET
NUM:
DB 01H,02H,03H,04H,05H,06H,07H,08H,09H,10H,11H,12H
END

这段程序应用于单片机与PC的串口通信，为什么结果是01 03 05 07 09 11 00 02 04 06 08 10

注意A的内容，指向单元