微机第一次实验（实现每隔1s在屏幕上显示你好，显示10次后退出）

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第三遍，一次成功。

.486
DATA SEGMENT USE16
	 MSG DB 'HELLO',0DH,0AH,'$'
	 OLD1C DD ?
	 ICOUNT DB 18	;中断服务子程序的
	 COUNT DB 10	;显示的行数
DATA ENDS
CODE SEGMENT USE16
	 ASSUME CS:CODE,DS:DATA
BEG: MOV AX,DATA
	 MOV DS,AX
	 CLI
	 CALL READ1C
	 CALL WRITE1C 
	 STI
AGA: CMP COUNT,0
	 JNZ AGA
	 CALL RESET
	 MOV AH,4CH
	 INT 21H
;-------------------------
READ1C PROC 
	   MOV AH,35H
	   MOV AL,1CH
	   INT 21H
	   MOV WORD PTR OLD1C,BX
	   MOV WORD PTR OLD1C+2,ES
	   RET
READ1C ENDP
;-------------------------
WRITE1C PROC
	 PUSH DS
	 MOV AX,CODE
	 MOV DS,AX
	 MOV DX,OFFSET SERVICE
	 MOV AH,25H
	 MOV AL,1CH
	 INT 21H
	 POP DS
	 RET
WRITE1C ENDP
;-----------------------------
SERVICE PROC 
	 PUSHA 
	 PUSH DS
	 MOV AX,DATA
	 MOV DS,AX
	 DEC ICOUNT 
	 JNZ EXIT
	 MOV ICOUNT,18
	 DEC COUNT
	 MOV AH,9
	 MOV DX,OFFSET MSG
	 INT 21H
EXIT:POP DS
	 POPA
	 IRET
SERVICE ENDP
;-----------------------------
RESET PROC 
	  MOV AH,25H
	  MOV AL,1CH
	  MOV DX,WORD PTR OLD1C
	  MOV DS,WORD PTR OLD1C+2
	  RET
RESET ENDP
CODE ENDS
	 END BEG

第二遍，看了一下课本，重新写了一下，运行正确。

;实现每隔1s在屏幕上显示你好，显示10次后退出
.486
DATA SEGMENT USE16
	 ICOUNT DB 18		;中断计数器初值
	 ICOUNT1 DB 10		;显示行数控制
	 OLD1C DD ?
     MSG DB 'HELLO,HELLO!',0DH,0AH,'$'
DATA ENDS
CODE SEGMENT USE16
	 ASSUME DS:DATA,CS:CODE
BEG: MOV AX,DATA
	 MOV DS,AX
	 CLI		;关中断
	 CALL READ1C   ;读出老的1CH中断
	 CALL WRITE1C  ;写入新的1CH中断
	 STI		;开中断
AGA: CMP ICOUNT1,0
	 JNZ AGA
	 CALL RESET	   ;把旧的中断重写进去
	 MOV AH,4CH
	 INT 21H
	 
;----------------------------
READ1C PROC					;读老的1CH中断
	 MOV AH,35H
	 MOV AL,1CH
	 INT 21H
	 MOV WORD PTR OLD1C,BX
	 MOV WORD PTR OLD1C+2,ES
	 RET
READ1C ENDP
;------------------------------------
SERVICE PROC				;中断服务程序
		PUSHA
		PUSH DS				;DS=40H
	 	MOV AX,DATA
	 	MOV DS,AX
	 	DEC ICOUNT	
	 	JNZ EXIT     	;不满18次结束
	 	MOV ICOUNT,18
	 	DEC ICOUNT1		;显示的行数减1
	 	MOV AH,9
	 	MOV DX,OFFSET MSG
	 	INT 21H
EXIT:	POP DS
	 	POPA
	 	IRET
SERVICE ENDP
;-----------------------------------
WRITE1C PROC 
		PUSH DS
		MOV AX,CODE
		MOV DS,AX
		MOV DX,OFFSET SERVICE
		MOV AH,25H
		MOV AL,1CH
		INT 21H
		POP DS
		RET
WRITE1C ENDP
;-----------------------------------
RESET PROC 
	 MOV AH,25H
	 MOV AL,1CH
	 MOV DX,WORD PTR OLD1C
	 MOV DS,WORD PTR OLD1C+2
	 INT 21H
	 RET
RESET ENDP
CODE ENDS
	 END BEG	 

开始凭感觉写，什么都不懂写的乱七八糟的代码。

;实现每隔1s在屏幕上显示你好，显示10次后退出
.486
DATA SEGMENT USE16
	 ICOUNT DB 18
	 ICOUNT1 DB 10
	 OLD1C DB '?','?'
     MSG DB 'HELLO,HELLO!',ODH,0AH,'$'
DATA ENDS
CODE SEGMENT USE16
	 ASSUME DS:DATA,CS:CODE
BEG: MOV AX,DATA
	 MOV DS,AX
	 CLI		;关中断
	 CALL READ1C   ;读出老的1CH中断
	 CALL WRITE1C  ;写入新的1CH中断
AGA: CMP ICOUNT1,0
	 JNC AGA
	 CALL RESET	   ;把旧的中断重写进去
	 MOV AH,4CH
	 INT 21H
	 
;----------------------------
PROC READ1C 
	 MOV AH,35H
	 MOV AL,1CH
	 INT 21H
	 MOV WORD PTR OLD1C,BX
	 MOV WORD PTR OLD1C+2,ES
	 IRET
READ1C ENDP
;------------------------------------
PROC WRITE1C
	 PUSHF
	 PUSH DS	;DS=40H
	 MOV AX,CS
	 MOV DS,AX
	 MOV DX,0FFSET SERVICE
	 DEC ICOUNT	
	 DEC ICOUNT1
	 JNZ EXIT     	;不满18次结束
	 MOV AH,9
	 MOV DX,0FFSET MEG
	 INT 21H
EXIT:POP DS
	 POPA
	 IRET
WRITE1C ENDP
;------------------------------------
PROC RESET 
	 MOV AH,25H
	 MOV AL,1CH
	 MOV DX,WORD PTR 0LD1C
	 MOV DS,WORD PTR OLD1C+2
	 INT 21H
RESET ENDP
;-----------------------------------