ToC
- 实验内容
- 实验接线
- 代码
- 选做实验 1
- 描述
- 分析
- 代码
- 选做实验 2
- 描述
- 分析
- 代码
实验内容
- 程序开始时
LED灯D7-D0全亮。 - 按下单脉冲开关
KK1，响应IR6中断请求，使绿灯（D3-D0）亮，红灯（D7-D4）灭。 - 按下单脉冲开关
KK2，响应IR7中断请求，使红灯（D7-D4）亮，绿灯（D3-D0）灭。
实验接线
LED 连接 8255 的 B 口，KK1+ 连接 MIR6，KK2+ 连接 MIR7。如下图所示：
代码
CODE SEGMENT
ASSUME CS:CODE
START:
MOV AX, 0
MOV DS, AX
;; INIT 8255
MOV DX, 0646H
MOV AL, 90H ;; 10010000B, INPUT FROM A & OUTPUT TO B
OUT DX, AL
;; MIR6
MOV AX, OFFSET MIR6 ;; PUT CS:IP TO INTERRUPT VECTOR ADDRESS
;; 6: 38H - 3BH
;; IP -> 38H
;; CS -> 3AH
MOV SI, 38H
MOV [SI], AX
MOV AX, CS
MOV SI, 3AH
MOV [SI], AX
;; MIR7
MOV AX, OFFSET MIR7 ;; 7: 3CH - 3FH
;; IP -> 3CH
;; CS -> 3AH
MOV SI, 3CH
MOV [SI], AX
MOV AX, CS
MOV SI, 3EH
MOV [SI], AX
;; --------------------------------------------------
;; INIT 8259
CLI ;; DISABLE INTERRUPT
MOV AL, 11H ;; ICW1 00010001B
;; ----A-BC
;; A: 1=HIGH, 0=UPPER EDGE
;; B: 1=SINGLE, 0=MULTIPLE
;; C: NEED ICW4
OUT 20H, AL
MOV AL, 08H ;; ICW2 00001000B
;;
OUT 21H, AL
MOV AL, 04H ;; ICW3 00000100B
;; -----AB-
;; A: 1 = INNER SUB 8259 CONNECTED TO IR2
;; 0 = NOT USED
;; B: ANY 8259 CONNECTED TO MAIN IR1
OUT 21H, AL
MOV AL, 07H ;; ICW4 00000111B
;; ----ABC-
;; A: 1 = BUFFERED
;; 0 = NOT BUFFERED
;; B: 1 = MAIN
;; 0 = SUB
;; C: 1 = AUTO INTERRUPT STOP
;; 0 = NOT AUTO
OUT 21H, AL
MOV AL, 2FH ;; OCW1 00101111B
;; M7 - M0
;; 0 = ALLOWED
;; 1 = DISABLED
;; IR4 IS USED TO COMMUNICATE WITH PC
OUT 21H, AL
STI ;; ALLOW INTERRUPT
;; --------------------------------------------------
AA1: ;; MAIN
MOV DX, 0642H
MOV AL, 0FFH
OUT DX, AL
JMP AA1
MIR6:
MOV DX, 0642H
MOV AL, 0FH ;; GREEN LIGHT
OUT DX, AL
CALL DELAY
IRET
MIR7:
MOV DX, 0642H
MOV AL, 0F0H
OUT DX, AL ;; RED LIGHT
CALL DELAY
IRET
DELAY PROC NEAR
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
RET
DELAY ENDP
CODE ENDS
END START
选做实验 1
描述
使用单脉冲开关控制 LED 的移动方向，初始状态仅点亮 D7。
当 KK1 按下时，LED 灯向右移动；当 KK2 按下时，LED 灯向左移动；当 LED 灯移动到单侧边界时，停止移动。
分析
需要保存当前移动的状态，使得中断嵌套执行完后原中断不继续执行。
代码
CODE SEGMENT
ASSUME CS:CODE
START:
;; BH: MODIFIED
;; BL: STATUS
MOV BX, 0080H
;; INIT 8255
MOV DX, 0646H
MOV AL, 90H ;; 10010000B, INPUT FROM A & OUTPUT TO B
OUT DX, AL
;; MIR6
MOV AX, OFFSET MIR6 ;; PUT CS:IP TO INTERRUPT VECTOR ADDRESS
;; 6: 38H - 3BH
;; IP -> 38H
;; CS -> 3AH
MOV SI, 38H
MOV [SI], AX
MOV AX, CS
MOV SI, 3AH
MOV [SI], AX
;; MIR7
MOV AX, OFFSET MIR7 ;; 7: 3CH - 3FH
;; IP -> 3CH
;; CS -> 3AH
MOV SI, 3CH
MOV [SI], AX
MOV AX, CS
MOV SI, 3EH
MOV [SI], AX
;; --------------------------------------------------
;; INIT 8259
CLI ;; DISABLE INTERRUPT
MOV AL, 11H ;; ICW1 00010001B
;; ----A-BC
;; A: 1=HIGH, 0=UPPER EDGE
;; B: 1=SINGLE, 0=MULTIPLE
;; C: NEED ICW4
OUT 20H, AL
MOV AL, 08H ;; ICW2 00001000B
;;
OUT 21H, AL
MOV AL, 04H ;; ICW3 00000100B
;; -----AB-
;; A: 1 = INNER SUB 8259 CONNECTED TO IR2
;; 0 = NOT USED
;; B: ANY 8259 CONNECTED TO MAIN IR1
OUT 21H, AL
MOV AL, 07H ;; ICW4 00000111B
;; ----ABC-
;; A: 1 = BUFFERED
;; 0 = NOT BUFFERED
;; B: 1 = MAIN
;; 0 = SUB
;; C: 1 = AUTO INTERRUPT STOP
;; 0 = NOT AUTO
OUT 21H, AL
MOV AL, 2FH ;; OCW1 00101111B
;; M7 - M0
;; 0 = ALLOWED
;; 1 = DISABLED
;; IR4 IS USED TO COMMUNICATE WITH PC
OUT 21H, AL
STI ;; ALLOW INTERRUPT
;; --------------------------------------------------
AA1: ;; MAIN
MOV DX, 0642H
MOV AL, BL
OUT DX, AL
JMP AA1
MIR6:
STI
MOV BH, 1
MOV DX, 0642H
IR6_RIGHT:
CMP BL, 1 ;; MOST RIGHT
JE IR6_STOP
SHR BL, 1
MOV AL, BL
OUT DX, AL
CALL DELAY
CMP BH, 1 ;; CHECK WHETHER NESTED INTERRUPT HAPPENED
JNE IR6_STOP
JMP IR6_RIGHT
IR6_STOP:
MOV BH, 0
IRET
MIR7:
STI
MOV BH, 1
MOV DX, 0642H
IR7_LEFT:
CMP BL, 80H ;; MOST LEFT
JE IR7_STOP
SHL BL, 1
MOV AL, BL
OUT DX, AL
CALL DELAY
CMP BH, 1 ;; CHECK WHETHER NESTED INTERRUPT HAPPENED
JNE IR7_STOP
JMP IR7_LEFT
IR7_STOP:
MOV BH, 0
IRET
DELAY PROC NEAR
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
RET
DELAY ENDP
CODE ENDS
END START
选做实验 2
描述
在选做实验 1 的基础上，增加：
- 在向左移动过程中，如果要求其向右移动，则立即改变方向，向右移动。到最右侧后，向左移动到最左侧。
- 在向右移动中，如果要求其向左移动，不立即改变方向，等到移动到最右侧后再开始向左移动。
分析
在当前移动状态的基础上，增加是否需要向左移动的标志。在向右移动中断处理程序（MIR6）的最后，当需要向左移动时，则调用向左移动中断处理程序（MIR7）。
代码
CODE SEGMENT
ASSUME CS:CODE
START:
;; BH: MODIFIED
;; 00 = IDLE
;; 01 = GOING_LEFT
;; 10 = GOING_RIGHT
;; 11 = GOING_RIGHT(DEFER GO RIGHT)
;; BL: STATUS
MOV BX, 0080H
;; INIT 8255
MOV DX, 0646H
MOV AL, 90H ;; 10010000B, INPUT FROM A & OUTPUT TO B
OUT DX, AL
;; MIR6
MOV AX, OFFSET MIR6 ;; PUT CS:IP TO INTERRUPT VECTOR ADDRESS
;; 6: 38H - 3BH
;; IP -> 38H
;; CS -> 3AH
MOV SI, 38H
MOV [SI], AX
MOV AX, CS
MOV SI, 3AH
MOV [SI], AX
;; MIR7
MOV AX, OFFSET MIR7 ;; 7: 3CH - 3FH
;; IP -> 3CH
;; CS -> 3AH
MOV SI, 3CH
MOV [SI], AX
MOV AX, CS
MOV SI, 3EH
MOV [SI], AX
;; --------------------------------------------------
;; INIT 8259
CLI ;; DISABLE INTERRUPT
MOV AL, 11H ;; ICW1 00010001B
;; ----A-BC
;; A: 1=HIGH, 0=UPPER EDGE
;; B: 1=SINGLE, 0=MULTIPLE
;; C: NEED ICW4
OUT 20H, AL
MOV AL, 08H ;; ICW2 00001000B
;;
OUT 21H, AL
MOV AL, 04H ;; ICW3 00000100B
;; -----AB-
;; A: 1 = INNER SUB 8259 CONNECTED TO IR2
;; 0 = NOT USED
;; B: ANY 8259 CONNECTED TO MAIN IR1
OUT 21H, AL
MOV AL, 07H ;; ICW4 00000111B
;; ----ABC-
;; A: 1 = BUFFERED
;; 0 = NOT BUFFERED
;; B: 1 = MAIN
;; 0 = SUB
;; C: 1 = AUTO INTERRUPT STOP
;; 0 = NOT AUTO
OUT 21H, AL
MOV AL, 2FH ;; OCW1 00101111B
;; M7 - M0
;; 0 = ALLOWED
;; 1 = DISABLED
;; IR4 IS USED TO COMMUNICATE WITH PC
OUT 21H, AL
STI ;; ALLOW INTERRUPT
;; --------------------------------------------------
AA1: ;; MAIN
MOV DX, 0642H
MOV AL, BL
OUT DX, AL
JMP AA1
;; --------------------------------------------------
MIR6: ;; INTEND TO GO RIGHT
STI
MOV DX, 0642H
;; PRESS KK1 WHEN GOING RIGHT
TEST BH, 10B
JNZ IR6_EXIT_IRET
;; BH MUST BE 0 OR 1
;; BH = 0 ==> MOV BH, 10B
;; BH = 1 ==> MOV BH, 11B
OR BH, 10B
IR6_RIGHT:
CMP BL, 1 ;; MOST RIGHT
JE IR6_LEFT
SHR BL, 1
MOV AL, BL
OUT DX, AL
CALL DELAY
JMP IR6_RIGHT
IR6_LEFT:
TEST BH, 1 ;; NEED TO GO LEFT
JZ IR6_EXIT
MOV BH, 1 ;; SET MODE TO GOING_LEFT
JMP MIR7
IR6_EXIT: ;; NORMAL EXIT
MOV BH, 0
IR6_EXIT_IRET:
IRET
;; --------------------------------------------------
MIR7: ;; INTEND TO GO LEFT
STI
TEST BH, 10B ;; GOING TO RIGHT NOW
JNZ IR7_IRET ;; EXIT
MOV BH, 1
MOV DX, 0642H
IR7_LEFT:
CMP BL, 80H ;; MOST LEFT
JE IR7_STOP
SHL BL, 1
MOV AL, BL
OUT DX, AL
CALL DELAY
CMP BH, 1 ;; WHETHER TO CONTINUE GOING LEFT
JNE IR7_STOP
JMP IR7_LEFT
IR7_STOP:
MOV BH, 0 ;; BACK TO IDLE
IRET
IR7_IRET:
OR BH, 01B ;; GO TO LEFT AFTER RIGHT FINISHED
IRET
DELAY PROC NEAR
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
MOV CX, 0FFFFH
LOOP $
RET
DELAY ENDP
CODE ENDS
END START