Using the Val Assembler

Using the 8088 Assembler

Installing the Assembler

If you don't already have access to an assembler for the Intel 8088 you can download an archive file containing a free assembler, valarrow.zip (about 107 kB). You'll need a utility such as unzip to extract the assembler files on a DOS PC. The only two files you need to keep are ASM.EXE and VAL.EXE.

You can also use any assembler (e.g. MASM or TASM) that uses standard Intel mnemonics and operand syntax.

Using the Assembler

Use a text editor (for example, the DOS EDIT program) to create the assembly language file. Use a file type extension of .asm. To assemble your program into an object (.obj) file use the command (assuming the file name is asg2.asm):

        asm asg2;

If it assembles without errors you can "link" it into an executable MS-DOS "COM" (.com) file using the command:

        val /co asg2;

(the /co options is required). Then you can run the program by typing

        asg2

Assembler Directives

You'll need to include a few assembler directives at the start of your assembly language program to make sure that: (1) the linker knows the object file contains executable code, (2) the assembler knows how the segment registers will be set up when the program is loaded, and (3) the executable code is placed at the right starting location within the code segment. Add the following 3 lines before your code:

code    segment public          ; (1)
        assume  cs:code,ds:code ; (2)
start:  org     100h            ; (3)

and the following 2 lines at the end of your code:

code    ends                    ; (1)                           
        end     start           ; (3)

to perform these functions. When your program is executed, DOS will load the code into memory, set the DS and CS segment registers to the appropriate values, set SS to the top of the 64k segment and start execution at location CS:100H.

Your code should terminate using the instruction

        int     20h

to return control to DOS

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