CSEG SEGMENT

 ASSUME CS:CSEG, DS:CSEG, SS:CSEG

 ORG 100h

START:MOV AX, CSEG; Initialise data segment

 MOV DS, AX; register using AX

 MOV AL, NUM1; Take the first number in AL

ADD AL, NUM2;                                          Add the 2^nd number to it

 MOV RESULT, AL;                                                 Store the result in location RESULT 

 RCL AL, 01;                                                  rotate carry into LSB

 AND AL, 00000001B;                                  Mask out all but LSB

MOV CARRY, AL;                                       Store the carry result

MOV AX,4C00h 

INT 21h

NUM1 DB                  15h;                             First number stored here

NUM2 DB                  20h;                             Second number stored here

RESULT DB              ? ;                                Put sum here

CARRY DB               ? ;                                Put any carry here

CSEG ENDS

END START

These programs are stored on a disk with an extension .com. A COM program needs less space on disk instead of equivalent EXE program. At run-time COM program places stack automatically at the end of segment so they use at least one complete segment.