mov ds, seg buff ; works in MASM
mov si, offset buff

All you need is the segment address on which the buff string
lies, this is because your generating an .EXE.

Here's one way to wait for a...

To print out your commandline arguments with
function 9, simply add a '$' to the end of the actual command tail.
example:

xor bx, bx
mov bl, [0x80]
mov byte [bx+0x81],'$'
mov bx, 0x81

But...

Let's see.
Does it have to be based on the code you showed?
Does it have to be a working program?
Does it have to manage multiple tasks?

If all else fails try making a program that loads a...

INT 21 - DOS 2+ - "LSEEK" - SET CURRENT FILE POSITION
AH=42h
AL=origin of move
00h - start of file
01h - current file position
02h - end of file
BX=file handle
CX : DX = (signed) offset from...