### Problem #1

Introduction to stack

//Solution Lat sheet 4 page 1-2 //Code .MODEL small .STACK 4h .DATA .CODE MAIN PROC mov ax, @data mov ds, ax mov ax, 0f0fh push ax inc ax push ax pop bx pop cx pop dx pushf popf ENDP MAIN end MAIN

### Problem #2 (Section 8.2)

Write a code to take an input string and print the string in reverse.

//Solution .MODEL small .STACK 100h .DATA .CODE MAIN PROC mov ax, @data mov ds, ax mov cx, 0 mov ah, 1 top: int 21h cmp al, 0dh je end_top push ax inc cx jmp top end_top: mov ah, 2 mov dl, 0dh int 21h mov dl, 0ah int 21h print: pop dx int 21h loop print ENDP MAIN end MAIN

### Problem #3

Introduction to procedure

//Solution .MODEL small .STACK 100h .DATA .CODE MAIN PROC mov ax, @data mov ds, ax mov ax, 2 mov bx, 3 call a mov ax, 4ch int 21h ENDP MAIN a proc add ax, bx ret endp a end MAIN

### Problem #4

Write a code with a multiply procedure.

//Solution .MODEL small .STACK 100h .DATA .CODE MAIN PROC mov ax, @data mov ds, ax mov ax, 20 mov bx, 2 call mult mov ax, 4ch int 21h ENDP MAIN mult proc push ax push bx xor dx, dx repeat: test bx, 1 jz end_if add dx, ax end_if: shl ax, 1 shr bx, 1 jnz repeat pop bx pop ax ret mult endp

### Problem #5

Multiplication procedure by addition

//Solution .MODEL small .STACK 100h .DATA .CODE MAIN PROC mov ax, @data mov ds, ax mov ax, 20 mov bx, 2 call mult mov ax, 4ch int 21h ENDP MAIN mult proc push ax push bx push cx xor cx, cx mov cx, bx xor dx, dx mult_: add dx, ax loop mult_ pop cx pop bx pop ax ret mult endp end MAIN

### Problem #6

Multiply and division instruction

//Solution mov ax, 2 mov bx, 010ffh mul bx mov ax, 2 mov bx, 010ffh imul bx mov ax, 2 mov bx, 010ffh div bx mov ax, 2 mov bx, 010ffh idiv bx

### Problem #7

Write a program that prompts the user to enter two binary numbers of up to 8 digits each, and prints their sum on the next line in binary. If the user enters an illegal character, he or she should be prompted to begin again. Each input ends with a carriage return.

Sample execution:

TYPE A BINARY NUMBER, UP TO 8 DIGITS: 11001010

TYPE A BINARY NUMBER, UP TO 8 DIGITS: 10011100

THE BINARY SUM IS 101100110

//Solution To be done by students

## Homework

Chapter 7 Problem 9

Chapter 7 Problem 10

Chapter 7 Problem 11

Chapter 7 Problem 13

Chapter 7 Problem 14