org     100h

; first, we need to free the conventional memory we don't use,
; so there will be some memory available for the program we want
; to run, if we used MZ format of executable, the directive
; "heap 0" would be enough for this purpose, in case of .com
; program we have to free that memory manually be resizing the
; memory block starting at our PSP (es is already set to it)

        mov     ah,4Ah                  ; resize memory block
        mov     bx,10010h shr 4         ; only memory needed for .com
        int     21h

; now set up the pointer to command line in the parameters block

        mov     word [cmdline],_command
        mov     word [cmdline+2],ds

; we are ready to execute the program now

        mov     ax,4B00h                ; load and execute program
        mov     dx,_program             ; ASCIIZ path of program
        mov     bx,params               ; parameter block
        int     21h

        int     20h                     ; exit program


_program db 'c:\command.com',0
_command db 0                           ; length of command line
         db 13                          ; must end with CR character

params:
 environment dw 0       ; segment of environment, 0 means to use parent's one
 cmdline dd ?           ; pointer to command line
 default_fcb1 dd 0      ; pointers to file control blocks
 default_fcb2 dd 0