.model tiny
.stack 32
.data
num1 db 8
num2 db 5
result dw 00
.code
.startup
mov ax,@data
mov ds,ax
mov ax,0
mov al,num1
mov bl,num2
add al,bl
mov result,ax
.exit
end
- goto dos prompt
- type edit.com or edit
- enter the source code from the observation book
- save the file as mfp.asm and exit the editor
- type dir mfp.* , find that mfp has 1 file .asm
- invoke the assembler and give the file to assemble
- type TASM mfp.asm
- type dir mfp.* , find that mfp has 2 files .asm,.obj
- type TLINK mfp.obj
- type dir mfp.* , find that mfp has 5 files .asm,.obj,.lst.map.exe
-execute td.exe
-press ALT+F+O select MFP.EXE
- notice the code assembly cum machine code
- left most is the CS:IP values
- next the machine code instruction
-next are the labels and memory references
-rightmost are the mnemonic instructions used in the source code
-the window on the right is the 16 bit register contents
- the execution of each instruction may be controlled using F7 & F8
F7----single step execution
executes one instruction at a time
F8----single step over execution
exectues one instruction at a time and for a CALL instruction it executes the complete subroutine called and returns to the next instruction in the calling module execution)
The initial objective is to understand the result of each instructions execution
Trace through each instruction while checking the change in contents
of the registers (in the Derbuuger registers window) and verify wether
the execution of the code is as expected if not find out the reason