INT 21h (33)             DOS Serivce Calls

Most of the DOS functions are implemented as sub-functions of DOS 21h,
which are listed under Services in the DOS menu.

                                                                          

Note:          In general, you should choose to use the DOS service
under INT 21h when you have a choice between an
interrupt (like INT 27h) and a DOS service (like INT
21h, function 31h).

The "See also" reference above will take you to the
first DOS service, function 00h.

See also: 00h

INT 21h (33) DOS Service Calls