ADD A,@R1 PUSH PSW MOV @R1,A INC R1 MOV @R1,B MOV A,33H MOV B,#3 MUL AB POP PSW ADDC A,@R1 MOV @R1,A
14.若晶振为6MHz，用T0产生500us的定时中断，试编写有关的初始化程序和对时钟进行计数的T0中断服务程序。时钟计数单元为：30H，31H，32H，分别存放压缩BCD码的时分秒参数。
答：晶振为6MHz，机器周期T为2μs，500us=250T，T0可以工作在方式2。有关的初始化程序和对时钟进行计数的T0中断服务程序如下： ORG 0000H SJMP MAIN ORG 000BH SJMP PT0 ORG 0030H MAIN: MOV TMOD,#02H MOV TH0,#6 MOV IE,82H SETB TR0 CLR A MOV 30H,A MOV 31H,A MOV 32H,A MOV 33H,A MOV 34H,A MOV 35H,A MOV R7,#40 MOV R6,#50 SJMP $ PT0: DJNZ R7,A1 MOV R7,#40 DJNZ R6,A1 MOV R6,#50 INC 33H
CJNE 33H,#60,A2 MOV 33H,#0
MOV 30H,#0 INC 34H
CJNE 34H,#60,A3 MOV 34H,#0 MOV 31H,#0 INC 35H
CJNE 35H,#24,A4 MOV 35H,#0 MOV 32H,#0 A1: RETI
A2: MOV A,33H MOV B,#10 DIV AB SWAP A MOV 30H,B MOV R0,#30H XCHD A,@R0 MOV 30H,A SJMP A1 A3: MOV A,34H MOV B,#10 DIV AB SWAP A MOV 31H,B MOV R0,#31H XCHD A,@R0 MOV 31H,A SJMP A1 A4: MOV A,35H MOV B,#10 DIV AB SWAP A MOV 32H,B MOV R0,#32H XCHD A,@R0 MOV 32H,A SJMP A1
15.在一个8031系统中，晶振为12MHz，P1口上输入8路脉冲，频率为0.1-3Hz，现用T0产生1ms定时，由T0中断服务程序读P1口的状态，若发生上跳则该路软件计数单元加1，每到1分钟将各路计数值拆分成2位十六进制数送显示缓冲区70H-7FH，并清零各计数器，试编写有关程序。
答：设置8路脉冲计数值缓冲区60H-67H，机器周期T=1μs，1ms=1000T,T0工作在方式1，
ORG 0000H SJMP MAIN ORG 000BH SJMP PT0 ORG 0030H MAIN: MOV TMOD,#01H MOV TH0,#0FCH MOV TL0,#18H MOV IE,82H SETB TR0
CLR A MOV 60H,A MOV 61H,A MOV 62H,A MOV 63H,A MOV 64H,A MOV 65H,A MOV 66H,A MOV 67H,A MOV 70H,A MOV 71H,A MOV 72H,A MOV 73H,A MOV 74H,A MOV 75H,A MOV 76H,A MOV 77H,A MOV 78H,A MOV 79H,A MOV 7AH,A MOV 7BH,A MOV 7CH,A MOV 7DH,A MOV 7EH,A MOV 7FH,A MOV R7,#8 MOV R0,#60H MOV R1,#70H MOV 68H,P1 MOV 69H,P1 SJMP $ PT0: MOV 6AH,P1 MOV 6BH,P1 PUSH ACC
A3: MOV A,68H RRC A MOV 68H,A JC A0 MOV A,6AH RRC A MOV 6AH,A JNC A1 INC @R0 MOV A,@R0 ANL A,#0FH MOV @R1,A MOV A,@R0 SWAP A ANL A,#0FH INC R1 MOV @R1,A DEC R1 A2: INC R0 INC R1 INC R1
DJNZ R7,A3 MOV 68H,6BH POP ACC RETI
A0: MOV A,6AH RRC A MOV 6AH,A A1: SJMP A2
16.在某应用系统中，有A-T20个单字符合法命令，这些命令的处理程序入口地址依次存放在标号为CADR开始的地址表中，若输入的命令字符存放于A，试编写一个散转程序，其功能为：若(A)为非法字符，则转CDER；若为合法字符，则转相应的入口地址。 答：A-T字符对应的ASC码16进制数为41H-54H, 散转程序为：
PUSH ACC CLR C
SUBB A,#55H JNC CDER POP ACC PUSH ACC CLR C
SUBB A,#41H JC CDER POP ACC
MOV B,#3 MUL AB
MOV DPTR,#CADR JMP @A+DPTR CADR:LJMP PGA LJMP PGB …
CDER:非法字符处理
《单片机原理与应用》第三版赵德安课后习题答案
