.MODEL SMALL
.STACK 100H
.DATA
MSG DB "Th*s *s a bas*c programming"
.CODE
MAIN proc
MOV AX,@DATA
MOV DS,AX

MOV CX,27
XOR SI,SI

TOP:
cmp MSG[si],'*'
JE NEXT
NEXT: MOV[si],'i'
INC SI
LOOP TOP

MOV Ah,4CH
int 21h
MAIN ENDP
END MAIN