Introduction to ibm pc assembly language
- 1. A solution manual to Assembly language Programming and the organization of the IBM PC Chapter 4 Introduction to IBM PC Assembly language BY:- Ytha Yu & Charles Marut prepared by : Warda Aziz [email protected]
- 2. Question 1: Which of the following names are legal in IBM PC assembly language? Names Status TWO_WORDS Legal ?1 Legal Two words illegal .@? illegal $145 legal Let’s_go illegal T= illegal Question 2: Which of the following names are legal numbers? If they are legal , tell whether they are binary , decimal or hex? Numbers Status 246 decimal 246h hex 1001 decimal 1,101 illegal 2A3h hex FFFEh illegal 0Ah hex Bh illegal 1110B binary Question 3: If it is legal, give data definition pseudo-ops to define each of the following . a) A word variable A initialized to 52 b) A word variable WORD1 uninitialized. c) A byte variable B initialized to 25h d) A byte variable C1, uninitialized e) A word variable WORD1, initialized to 65536 f) A word array ARRAY1, initialized to the first five positive integers g) A constant BELL equal to 07h h) a constant message equal to ‘THIS IS A MESSAGE$’ Solution: A word variable A initialized to 52 A DW 52 A word variable WORD1 uninitialized. WORD1 DW ? A byte variable B initialized to 25h B DB25h A byte variable C1, uninitialized C1 DB ? A word variable WORD1, initialized to 65536
- 3. WORD1 DW 65536 A word array ARRAY1, initialized to the first five positive integers ARRAY1 DW 1,2,3,4,5 A constant BELL equal to 07h BELL EQU 07h A constant message equal to ‘THIS IS A MESSAGE$’ MSG EQU ‘THIS IS A MESSAGE$’ Question 4: Suppose that the following data are loaded starting at offset 0000h A DB 7 B DW 1ABCh C DB ‘HELLO’ a. Give the offset address assigned to variables A,B and C b. Give the contents of the byte at offset 0002h in hex c. Give the contents of the byte at offset 0004h in hex d. Give the offset address of the character “O” in “HELLO” variable content Address A 7 0000 B BC 0001 1A 0002 C H 0003 E 0004 L 0005 L 0006 0 007 A) A: 0000 B: 0001 C: 0003 B) 1A C) E D)0007 Question 4: Tell whether each of the instructions is legal or illegal instruction status MOV DS,AX Legal MOV DS, 1000h Illegal ;can’t use seg register with an immediate value MOV CS,ES Illegal; seg registers cannot go together MOV W1, DS Legal XCHG W1,W2 Illegal SUB 5, B1 Illegal ADD B1,B2 illegal ADD AL, 256 illegal MOV W1,B1 Illegal Question 6: Using only MOV , ADD, SUB, INC, DEC and NEG , translate the following high level language assignment statements into assembly language A,B and C are word variables.
- 4. A) A=B-A B) A=-(A+1) C) C=A+B D) B=3*B+7 E) A=B-A-1 A=B-A MOV AX, a MOV BX, b SUB BX,AX MOV AX,BX A=-(A+1) MOV AX,A ADD AX,1 NEG AX MOV A,AX C=A+B MOV AX,A ADD AX,B MOV C,AX B=3*B+7 MOV AX,B ADD AX,B ADD AX,B ADD AX,7 MOV B,AX A=B-A-1 MOV BX,B SUB BX,A SUB BX,1 MOV A, BX Question 7: Write instructions to do the following. A. Read a character and display it at the next position on the same line B. Read an uppercase letter and display it at the next position on the same line in lower case Read a character and display it at the next position on the same line mov ah,1 int 21h mov ah,2 mov dl,al int 21h Read an uppercase letter and display it at the next position on the same line in lower case mov ah,1 int 21h add al,20h mov ah,2 mov dl,al int 21h
- 5. Question 8: Write a program to a) display a “?” b) read two decimal digits whose sum is less than 10 c)display them and their sum in the next line with an appropriate message. Code: .MODEL SMALL .STACK 100H .DATA MSG DB 0AH, 0DH, "The sum of " VAR DB ?, ' and ' var2 DB ? , ' is '; sum DB ?,"$" .CODE MAIN PROC ;DATA INITIALIZATION MOV AX, @DATA MOV DS, AX ; DISPLAY ? TO PROMPT THE USER FOR INPUT MOV AH, 2 MOV DL, '?' INT 21H ;READ DECIMAL DIGITS MOV AH, 1 INT 21H MOV VAR, AL ; storing var in another reg ;INPUT 2ND VARIABLE INT 21H ; storing VAR2 in AL MOV var2, AL ;ADDING VARIABLES ADD AL, VAR SUB AL, 30H ;there is ASCII coding in background so subtracting code 30h MOV SUM , AL ;DISPLAY MSG LEA DX, MSG MOV AH, 9 INT 21H ;DOS EXIT MOV AH, 4CH INT 21H MAIN ENDP END MAIN Output: Question 9: write a program to A) prompt the user B) Read first middle and last initials of a person’s name C) And display them down the left margin
- 6. Ans: .MODEL SMALL .STACK 100H .DATA MSG DB 0AH, 0DH,, "Enter three initials:$" A DB ? b DB ? c DB ? .CODE MAIN PROC MOV AX, @DATA MOV DS, AX ;DISPLAYING LINES LEA DX, MSG MOV AH, 9 INT 21H ;TAKING INPUT MOV AH, 1 ;First input INT 21H MOV A, AL INT 21H ;Second input MOV B, AL INT 21H ;3rd input MOV C, AL ;LINE FEED MOV AH,2 MOV DL, 0AH INT 21H MOV DL, 0DH INT 21H ;display function MOV AH, 2 MOV DL, A INT 21H ;LINE FEED MOV AH,2 MOV DL, 0AH INT 21H MOV DL, 0DH INT 21H ;DISPLAY 2ND NUM MOV AH, 2 MOV DL, B INT 21H ;LINE FEED MOV AH,2 MOV DL, 0AH
- 7. INT 21H MOV DL, 0DH INT 21H ;DISPLAY MOV AH, 2 MOV DL, C INT 21H ; DOS EXIT MOV AH, 4CH INT 21H MAIN ENDP END MAIN Output: Q 10: Write a program to read one of the hex digits A-F;and display it on the next line in decimal. Ans: .MODEL small .STACK 100h .DATA MSG DB 'enter a hex digit' C db ?, '$' MSG2 DB 0AH,0DH,"In decimal it is: 1" C2 db ?,'$' MAIN PROC MOV AX, @DATA MOV DS,AX ;Displaying first message MOV AH, 9 LEA DX, MSG INT 21H ;input MOV AH,1 INT 21H
- 8. MOV C, AL ;CALCULATION SUB AL, 11H MOV C2,AL ;DISPLAY MOV AH,9 LEA DX, MSG2 INT 21H ;DOS EXIT MOV AH, 4CH INT 21H MAIN ENDP END MAIN Output: Question 11: write a program to display a 10*10 solid box of asterisk. Hint: declare a string in the data segment that specifies the box and display it with INT 21h function 9h. Ans: .MODEL SMALL .STACK 100H .DATA MSG DW 0AH,0DH,'**********$' .CODE MAIN PROC MOV AX, @DATA MOV DS, AX ;FUNCTION 9 FOR DISPLAYING OUTPUT STRING MOV AH,9 LEA DX ,MSG INT 21H ;OUTPUT FOR first line INT 21H ;output for second line INT 21H ; . INT 21H ; . INT 21H ; . INT 21H ; . INT 21H ; . INT 21H ; . INT 21H ; . INT 21H ; output for the 10th line ;DOS EXIT MOV AH, 4CH INT 21H MAIN ENDP END MAIN
- 9. Output: Write a program to display a) ? b) Read three initials c) Display them in the middle of an 11*11 box of asterisk d) Beep the computer Ans: .STACK 100h .MODEL small .DATA msg DB "?$" msg1 DB 0Ah, 0Dh,"**********$" msg2 DB 0Ah, 0Dh,"***" ch1 DB ? ch2 DB ? ch3 DB ?,"****$" .CODE main PROC MOV AX, @DATA MOV DS, AX ;prompt the user for ? MOV AH,2 MOV DL, msg INT 21h ;enter initials MOV AH,1 int 21h MOV ch1, AL INT 21h MOV ch2, AL INT 21h MOV ch3, AL ; output MOV AH,9 lea DX, msg1 INT 21h INT 21h INT 21h INT 21h
- 10. INT 21h INT 21h LEA DX, msg2 INT 21h LEA DX, msg1 INT 21h INT 21h INT 21h INT 21h INT 21h ;BEEP THE COUNTER MOV AH, 2 MOV DL, 7H INT 21H ;dos exit MOV AH, 4Ch INT 21h main ENDP END main Output