DELAY_2S:     ;10MS(11.0592mhz)
  MOV R3,#200
  JMP DELAY10MS
DELAY_100MS:       ;100MS(11.0592mhz)
  MOV R3,#10
  JMP DELAY10MS
DELAY_10MS:
  MOV R3,#1
DELAY10MS:       ;去抖动10MS

(11.0592mhz)
  MOV R4,#20
DELAY10MSA:
  MOV R5,#247
  DJNZ R5,$
  DJNZ R4,DELAY10MSA
  DJNZ R3,DELAY10MS
  RET

/1.024=2390
  MOV   R0,#244   ;1
DELAY24001:
  MUL AB   ;4
  MUL AB   ;4
  DJNZ R0,DELAY24001 ;2
  RET

DELAY: ;延时子程序(1秒)
MOV R0,#0AH
DELAY1: MOV R1,#00H
DELAY2: MOV R2,#0B2H
DJNZ R2,$
DJNZ R1,DELAY2
DJNZ R0,DELAY1
RET

MOV R2,#10 ;延时1秒
LCALL DELAY
MOV R2,#50 ;延时5秒
LCALL DELAY
DELAY: ;延时子程序
PUSH R2
PUSH R1
PUSH R0
DELAY1: MOV R1,#00H
DELAY2: MOV R0,#0B2H
DJNZ R0,$
DJNZ R1,DELAY2 ;延时 100 mS
DJNZ R2,DELAY1
POP R0
POP R1
POP R2
RET

                     DEL1:     MOV     R6,     #123

                                               NOP

                     DEL2:     DJNZ     R6,     DEL2

                                               DJNZ     R7,     DEL1

                                               RET

是50.001ms 算法是:
0.001ms+200*0.001ms+200*0.001ms+200*123*0.002ms+200*0.002ms

;(123*2+4)*200+1

2: DEL: MOV R7, #200

  DEL1: MOV R6, #123

  DEL2:NOP

           DJNZ R6,DEL2

           DJNZ R7,DEL1

RET

D500MS:
PUSH PSW
SETB RS0
MOV R7,#200
D51: MOV R6,#250
D52: NOP
NOP
NOP
NOP
DJNZ R6,D52
DJNZ R7,D51
POP PSW
RET

   ORG     0
               LJMP       MAIN
                       ORG       000BH
               LJMP       CTC0
     MAIN:   MOV     SP, #50H
                   CLR     EA
                   MOV     TMOD, #01H
                   MOV       TH0,#3CH
                   MOV       TL0,#0B0H
                   MOV       R4,   #10
                     SETB     ET0
                     SETB     EA
                     SETB     TR0
                       SJMP   $   ;
     CTC0:     MOV   TH0, #3CH
                     MOV   TL0, #0B0H
                     DJNZ   R4, LP
                     CPL     P1.0
                     MOV     R4,   #10
         LP:       RETI
                   END