Begin from the beginning. . .

[eniwe]

i do not seem to be getting anywhere with my probe aimed at searchfirst, open file and overwrite and so on. Hence i have no other alternative other than start from scratch. Though my initial attempt to create an overwriting file, has failed, i did achieve substantial understanding of several difficult to pin down ideas like…DTA, 1eh, and a few more... Thanks to Salem.

Begin from the beginning. . .

To call the function 4Eh, I need to set up registers as shown:

mov ah, 4Eh
xor cx, cx
mov dx, offset Filetype

cx 0 means a normal file ; for example not one that is hidden.
Dx needs to have the address of the type of the file to be searched. In my case it was a .com file.

So, Filetype is defined as:
Filetype db *.com, 0

Now, int 21h is used to call the function 4Eh.

Have i prepared appropriately so far?
Is there any other value or register that i need to set up before using int 21h ?

Thank you..