1.    Download masm from http://www.masm32.com/


2.    Unzip the package and run install.exe


3.    Set the path to the compiler. Open “My computer”, right click and select “Properties”. Select “Advanced” -> “Environment variables”->”Path”. Click “Edit” and add “;c:\masm32\bin” to the path



4.    Check the installation by opening the command prompt window



and typing ML at the command prompt




5.    Download 16-bit version of the link.exe from the Microsoft’s website


Copy this file to C:\MASM32\BIN and run it. Answer Yes when asked whether to overwrite existing files.


6.    Download Code View Debugger


     Unzip all files to c:\masm32\bin


7.    Now you can use almost any text editor to create an assembly program. In this example, we will use Microsoft’s EDIT. Type “edit example1.asm” on the command prompt and enter the text of the program.


Save the file by “Alt-F”,”Alt+S”. Exit “Alt-F”,“Alt-X”


8.    Compile and link the assembly file by issuing “ml /Zi example1.asm”



9.    Now lets start and configure the Code View debugger. Type “cv example1.exe’ at the command prompt.

Enter “Alt-W” and make sure that you have the following windows on the screen:

-         Code 1

-         Registers

-         Memory 1

Press “Alt-F5” to arrange the windows on the screen.



Now lets set the options. “Alt-O” -> Preferences. Set the options as shown and click “ok”.



Again, “Alt-O” -> “Source 1 window”



“Alt-O” - >”Memory 1 window”



The configuration is now complete.


10.                       Lets look at the program.




11.                       Now lets step through the program and observe execution of each instruction.

-         Press “F10”.

-         The debugger will show execution of the first line of the prolog.

-         Press “F10” until instruction “MOV AX,0” is highlighted. This is the first instruction of your program.



Observe the value in the register EAX. Register AX contains number 09DFH.



Now press “F10”. The debugger will execute the highlighted instruction.

Note the change in the content of EAX and the fact that the register has been highlighted by the debugger, indicating the change.



The highlighting the code window moved to the next instruction.

Note that the line of the source code “MOV AL, VAR1” became
AL, [000C] where 000CH is the actual offset of VAR1 in the data segment. You can check that this is true by checking the content of memory location DS:000CH in the data window.

Now execute this instruction by pressing “F10”. Content of the register AL changed, taking the value from the VAR1.



The next instruction is “MOV BX, OFFSET VAR2”. VAR2 follows VAR1 in memory and has offset of 000DH. This is the value that will be placed into the BX upon execution of this instruction. Press “F10” to execute.



The following instruction “MOV [BX], AL” will copy the content of AL into the memory location pointed by BX within the data segment. After the previous instruction BX contains the offset of the first byte of VAR2 or 000DH. That is where the data from AL will appear. Press “F10” to execute.

Note the debugger also highlighted changes in the data window.



Instruction “MOV [BX+1], AL” will copy the content of the register AL into the memory location with offset equal whatever the number is in BX plus 1. In our case BX=000DH, then the offset is 000DH+0001H=000EH. That is the second byte of the VAR2. Press “F10” to execute. Note the change in the memory content.



Instruction “MOV EAX, 12345678H” will place number 12345678H into the register EAX. Press “F10” to execute.



The instruction “MOV VAR3, EAX” became

VAR3 has been replaced by the actual offset (000FH) of VAR3 in the data memory. This instruction will take the content of the EAX and place into the four consecutive bytes of memory (a 32-bit variable) starting with the offset 000FH. Press “F10” to execute.



That was the last instruction of the user program. The remaining instructions are generated by the .EXIT directive and serve to terminate the program. Press “F10” until the process terminates.



Still not clear how to work with the CodeView debugger?

Here is additional tutorials you can go through.


CodeView tutorial