Assembly language 1

1. Now create a MASM folder

LINK.EXE connection on the E drive
2. Write the code in EX11.ASM
The main frame of the assembly language

DATA SEGMENT

DATA ENDS
CODE SEGMENT
ASSUME   CS:CODE, DS:DATA
START:	MOV  AX, DATA
	MOV  DS,AX
	

	MOV AH, 4CH
	INT 21H
CODE ENDS
END 	START

The semicolon in the assembly language; indicates the comment. The
flag must be remembered:
https://wenku.baidu.com/view/71fe5f06cc17552707220801.html

DATA SEGMENT
	BUF1  DB  A8H,9FH,B4H,25H
	BUF2  DB  78H,FFH,D3H,5CH
	BUF3  DB  4  DUP(?) 
DATA ENDS
CODE SEGMENT
ASSUME   CS:CODE, DS:DATA
START:	MOV  AX, DATA
	MOV  DS,AX
	LEA  SI,BUF1
	LEA  DI,BUF2
	MOV BX,OFFSET BUF3
	MOV CX,4
	CLC 	;CF=0,  STC    CF=1//循坏
NEXT:	MOV   AL,[SI]//取字节
	MOV   DL,[DI]//取字节
	ADD AL,DL//相加
	MOV  [BX],AL//存数
	INC   SI//移指针
	INC   DI//移指针
	INC   BX//移指针
	DEC  CX//循环次数减1
	JNZ    NEXT	；ZF=0//循环回去

	MOV AH, 4CH
	INT 21H
CODE ENDS
END 	START

Running code

DATA SEGMENT
	BUF1  DB  A8H,9FH,B4H,25H
	BUF2  DB  78H,FFH,D3H,5CH
	BUF3  DB  4  DUP(?) 
DATA ENDS
CODE SEGMENT
ASSUME   CS:CODE, DS:DATA
START:	MOV  AX, DATA
	MOV  DS,AX
	LEA  SI,BUF1
	LEA  DI,BUF2
	MOV BX,OFFSET BUF3
	MOV CX,4
	CLC 	;CF=0,  STC    CF=1
NEXT:	MOV   AL,[SI]
	MOV   DL,[DI]
	ADD AL,DL
	MOV  [BX],AL
	INC   SI
	INC   DI
	INC   BX
	DEC  CX
	JNZ    NEXT	;ZF=0

	MOV AH, 4CH
	INT 21H
CODE ENDS
END 	START

2. Debug and download

Download

DOSBox-assembly environment construction steps
1. Download DOSBox0.74-win32-installer and install it
2. The icon appears on the desktop, click to enter the following interface: (Press alt + Enter to type full screen, then press alt + Enter to return to half screen)

3. Bind the MASM directory. The
MASM directory is located at E: \ MASM. There are several basic files for assembler design in this directory: MASM.exe (the assembler program developed by Microsoft, used to put the user-developed assembly language source The program * .asm is assembled into the target file * .obj), LINK.exe (used to connect the target file * .obj to generate * .exe executable file), debug.exe (debug file), EDIT.EXE (full screen text (Editor)
Binding method:
mount c: e: \ wmasm, type C: after pressing Enter, press Enter

The current C drive is associated with E: \ WMASM.
Type the dir command in the current C drive, you can see the files in the E: \ WMASM directory

The error in the second and third lines of code is because A is regarded as a variable in A8H, and 0 should be added in front.

DATA SEGMENT
	BUF1  DB  0A8H,9FH,0B4H,25H
	BUF2  DB  78H,0FFH,0D3H,5CH
	BUF3  DB  4  DUP(?) 
DATA ENDS

Next step: Connect to the

DEBUG command
Debug-R to view and change the contents of the CPU register
Debug-D to view the contents of the memory
Debug-E to rewrite the contents of the memory
Debug-U to translate the machine instructions in the memory into assembly instructions
Debug-T to execute A machine instruction
Debug-A writes a machine instruction in memory in the format of an assembly instruction

Original link: https://blog.csdn.net/qq_36215315/article/details/79893476

Although the instruction ADD in the code is compiled without error, the result is wrong, and ADC should be used.