Hi,

You can copy simple calc from here..

#make_com#
include 'emu8086.inc'

ORG 100h

JMP start

msg1 DB 'Enter operation number[1~4]: $'
msg2 DB 'Enter 1st No: $'
msg3 DB 'Enter 2nd No: $'
msg4 DB 'The result is: $'
msg5 db 'Thank you for using My Calculator Program ', 13, 10, '$'

calcOP DB '?', 0

num1 DW ?
num2 DW ?
opr DW ?


start:
PRINTN 'Welcome to My Calculator Program'
PRINTN '[Loading...]'
PRINTN ''
PRINTN ''
PRINTN 'Please select type of arithmetic operation:'
PRINTN '1. Addition'
PRINTN '2. Subtraction'
PRINTN '3. Multiplication'
PRINTN '4. Division'

LEA DX, msg1 ; output of a string at DSX
MOV AH, 09h
INT 21h

MOV DX, 2
LEA DI, calcOP
CALL GET_STRING

PUTC 13
PUTC 10

LEA DX, msg2 ; first number
MOV AH, 09h
INT 21h
CALL scan_num
MOV num1, CX

PUTC 13
PUTC 10

LEA DX, msg3 ; second number
MOV AH, 09h
INT 21h
CALL scan_num
MOV num2, CX

PUTC 13
PUTC 10

LEA DX, msg4 ; result
MOV AH, 09h
INT 21h

CMP calcOP, '1'
JE do_plus

CMP calcOP, '2'
JE do_minus

CMP calcOP, '3'
JE do_mult

CMP calcOP, '4'
JE do_div

end:
PUTC 13
PUTC 10

LEA DX, msg5
MOV AH, 09h
INT 21h

RET

do_plus:

MOV AX, num1
ADD AX, num2
CALL PRINT_NUM
JMP end

do_minus:

MOV AX, num1
SUB AX, num2
CALL PRINT_NUM
JMP end

do_mult:

MOV AX, num1
IMUL num2
CALL PRINT_NUM
JMP end

do_div:
MOV DX, 0
MOV AX, num1
IDIV num2
CALL PRINT_NUM
JMP end

DEFINE_SCAN_NUM
DEFINE_PRINT_NUM
DEFINE_PRINT_NUM_UNS
DEFINE_GET_STRING

END