Based on the assembly code 8086, with 8254 and 8255 chips
Function implementation is a whack-a-mole game
Principle of output is about 8255 a mouth as LED lights, as switch input port B, C as digital tube display
10 to 50 hz interrupt for a cycle, each interrupt to judge whether the switch change, if change compared with leds, consistent and scoring,
Ten Chinese break into the next cycle, lights up a light bulb,
Where don't understand:
1. Code snippet SET_NMI_INT, seems to be 8259 interrupt, but did not use 8259 chip, the test can't delete the code according to the logic operation,
2. The code segment UPDATE_LED, refresh the LED logic is he here?

 DATA SEGMENT 
I8253_1 EQU 0288 h 
I8253_2 EQU 028 ah 
I8253_MODE EQU 028 eh 
I8255_A EQU 0280 h 
I8255_B EQU 0282 h 
I7SEG_1 EQU 0284 h 
I8255_MODE EQU 0286 h 
3 fh SYMBOL_7SEG DB, 6 h, 5 bh, 4 fh, 66 h, 6 dh, 7 dh, 7 h, 7 fh, 6 fh 
Who leads the DB 0 
RANDOM_NUMBER DB? 
LED the DB 1 
SWITCH the DB? 
INT_TIMES DB 1 
The DATA ENDS 

Sports a SEGMENT STACK 
1024 DB DUP (0) 
Sports a ENDS 

CODE SEGMENT 
ASSUME CS: CODE, DS: DATA, SS: sports a 
START: 
MOV AX, DATA 
MOV DS, AX 
MOV AX, sports a 
MOV SS, AX 

MOV DX, I8255_MODE; Initialize the 8255 works 
MOV AL, 82 h 
The OUT DX, AL 

MOV DX, I8255_A; A output 
MOV AL, 0 
The OUT DX, AL 

MOV [RANDOM_NUMBER], 47 
MOV DX, I8255_B; B enter 
IN AL, DX 
MOV [SWITCH], AL 


CALL SET_NMI_INT 
CALL PRINT_SCORE 
CALL SET_TIMER 

@ WAIT: 
JMP @ WAIT 

SET_TIMER PROC NEAR 
MOV DX, I8253_MODE; Initialize the 8254 works 
MOV AL, 00100101 b 
The OUT DX, AL 
MOV DX, I8253_1 
MOV AL, 01 h 
The OUT DX, AL 
MOV DX, I8253_MODE 
MOV AL, 01100101 b 
The OUT DX, AL 
MOV DX, I8253_2 
MOV AL, 10 h 
The OUT DX, AL 
RET 
SET_TIMER ENDP 

SET_NMI_INT PROC NEAR 
PUSH the DS 
MOV AX, CS 
MOV DS, AX 
MOV DX, OFFSET NMI_HANDLER; Using indirect modification method, set the interrupt vector 
MOV AX, 250 bh. Setting the corresponding interrupt vector 
INT 21 h 
IN AL, 21 h. Read the interrupt mask register, register 21 h is the port number 
AND AL, 0 f7h; Interruption of open, allowing the interrupt application 
OUT of 21 h, AL 
STI 
POP the DS 
RET 
SET_NMI_INT ENDP 

UPDATE_LED PROC NEAR 
XOR AX, AX 
MOV AL, [RANDOM_NUMBER] 
PUSH AX 
MOV DL, 8 
DIV DL 

MOV CL, AH 
MOV BL, 1 
SHL BL, CL 
MOV [LED], BL 

POP AX 
MOV DL, 23 
The MUL DL 
MOV DL, 97 
DIV DL 
MOV [RANDOM_NUMBER], AH 

MOV DX, I8255_A 
MOV AL, BL 
The OUT DX, AL 
RET 
UPDATE_LED ENDP 

ADD_SCORE PROC NEAR; Scoring program 
MOV AL, [who] 
INC AL; If the score score + 1 
CMP AL, 10 
JNZ @ ADD_SCORE_NEXT; Digital tube is not equal to 10 jump, otherwise jump back to 0 
MOV AL, 0 
@ ADD_SCORE_NEXT: 
MOV [who], AL; Update the results after scoring 
RET 
ADD_SCORE ENDP 

PRINT_SCORE PROC NEAR; Digital tube scores show 
MOV DL, [who] 
MOV DH, 0 
MOV DI, OFFSET SYMBOL_7SEG 
The ADD DI, DX 

MOV DX, I7SEG_1 
MOV AL, BYTE PTR (DI) 
The OUT DX, AL 
RET 
PRINT_SCORE ENDP 

UPDATE the PROC NEAR; Update 
DEC [INT_TIMES]; Remaining flush time - 1 
JNZ @ UPDATE_ELSE; Not to 0 jump determine whether score 
MOV [INT_TIMES], 10; Accumulated in a side to enter the next lights 
CALL UPDATE_LED 
@ UPDATE_ELSE: 
MOV DX, I8255_B; Switch input 
IN AL, DX 
MOV CH, [SWITCH]; The light bulb output 
MOV [SWITCH], AL 
XOR AL, CH. Switch between two interrupt have change 
XOR AL [LED]; Change the switch to light up the light bulb is uniform 
JNZ @ UPDATE_NO_SCORE; Switch didn't change or isn't score 
CALL ADD_SCORE; Otherwise the score 
CALL PRINT_SCORE 
@ UPDATE_NO_SCORE: 
RET 
The UPDATE ENDP 

NMI_HANDLER: 
MOV AX, DATA 
MOV DS, AX 
MOV AX, sports a 
MOV SS, AX 
CALL the UPDATE 
MOV AL, 20 h; A EOI end interrupts to address of the PC NaZhu piece of 20 h 
OUT of 20 h, AL 
IRET 
CODE ENDS 
The END START 

CodePudding user response:

SET_NMI_INT should be called DOS modify the keyboard interrupt vector
UPDATE_LED should be calculated by a random number control led lights?