STACK SEGMENT STACK
    DB 200 DUP (0)
STACK ENDS
DATA SEGMENT
   SUM  DW ?
DATA ENDS
CODE SEGMENT
      ASSUME CS: CODE, DS: DATA, SS: STACK
BEGIN: MOV AX, DATA
       MOV DS, AX
       SUB AX, AX
       MOV AX, '1'
       MOV CX, 99
LOP:   ADD AX, AX
       DEC AX
       LOOP LOP
       MOV SUM, AX
       MOV AH, 4CH
       INT 21H
CODE ENDS
END BEGIN