Assembly Language Tutorial

 
 
 

Instructions

Input - Output Instructions

Display a character Read a character and display it on new line Display string Read digit, compute and display sum w/o variable Read digit, display difference w/o variable Read digit, compute, display sum using variable Read digit, display difference using variable Convert lower case letter in to upper case Read character, display in new line - user prompt Read 1st, middle, last initial - down left margin Read one hex digit, display next line in decimal Display 10*10 solid box asterisk - INT 21H and 9H Read 3 char show in middle of 11*11 box, beep comp

Flow Control Instructions

Print ASCII characters Print counting from 0 to 9 Print upper case letters from A to Z Print lower case letters from a to z in reverse Read letter print if it is \'?\' - simulation of if Read char print smallest - simulation of if-else Positive, negative num- simulation of switch-case Print upper case char - simulation of if-else then Simulation of if-else then structure Print ASCII characters - for loop simulation Print upper case A to Z - while loop simulation Print upper case A to Z - Do while loop simulation Read letters display in next line in alpha order Display digit in next line if fail prompt message Read hex digit display on next line in decimal Display capital letter in string alphabetically Show longest sequence consecutive alphabetically

Logic - Shift - Rotate Instructions

Convert upper to lower case - OR logic instruction Convert lower to upper - AND logic instruction Display even or odd number - TEST instruction Multiply content of AL by 8 - SHL instruction Divide content of AL by 4 - SHR instruction Store binary- BX,count bit value 1 w/o changing BX Read binary num, reverse its bit pattern Read binary number store in BX and display Read char- show ASCII in binary- 1 bit in ASC code Read char print ASCII in HEX till- carriage return Read HEX number and print in binary next line Read binary number and print in HEX next line Read 2 binary number and print its sum in binary Read 2 unsigned HEX num and print their sum Read string of decimal digit print sum in HEX Read str of char ter by CR show reverse order Read character using procedure goto next line Binary form & reverse bit of num - procedures Product by ADD, SHIFT instruction - procedure Display text with letters in each word reversed Validate expression READ store bin num in AX, RANDOM, WRITE

Multiplication - Division Instructions

Print factorial in binary form - MUL instruction Print num decimal form - DIV, OUTDEC proc Print factorial in decimal form - MUL, DIV instru Print num next line - proc for DECIMAL i/o Proc INDEC and OUTDEC, handle BackSpace key Proc INDEC and OUTDEC - files - INCLUDE instru Print factorial in dec form - MUL, DIV instruction Proc INDEC, OUTDEC - Handle OverFlow Read time in seconds display time HH:MM:SS Express - quarter, dime, nickel, pennie Read fraction form M/N print N decimal place GCD of two integers M and N

Arrays - Addressing Modes

Sum of array - sum in AX - Register Indirect Mode Initialize array with 0 using DUP instruction Enter an array of size 10 and display it Declare, initialize, print 2D array of size 5x5 Enter 2D array of 5x5 in row major order, print Print 3rd R x 4th C using Register Indirect Mode Display reversing array contents using STACK Reverse content of array - Register Indirect Mode Sort array using Bubble Sort method Sort an array using Select Sort method Print 2D array of size 4x5 in row major order Print 2D array of size 4x5 in column major order 2D arr clear 3rd row 4th column - Based Index Mode Compute class average on each exam Print name each student, average of 4 exams Insert single characters into array - it is sorted

String Instructions

Copy string into another using MOVSB, REP Read string, stores in variable using STOSB Display string using instruction LODSB Store display str - proc READ_STR, DISP_STR Count no of vowels constants - SCASB, REPNE

General Programs

Get and display the current system time
 
 
 .MODEL SMALL
 .STACK 100H

 .DATA
   PROMPT_1   DB \'Enter the binary number (0000000000000001 - 0111111111111111) : $\'
   PROMPT_2   DB  0DH,0AH,\'The 100 random numbers are :\',0DH,0AH,\'$\'
   AGAIN      DB  0DH,0AH,\'Invalid Number. Try Again : $\'
   BLANKS     DB  \'    $\'

   COUNTER_1  DB  25
   COUNTER_2  DB  ?

 .CODE
   MAIN PROC
     MOV AX, @DATA                ; initialize DS 
     MOV DS, AX

     LEA DX, PROMPT_1             ; load and display PROMPT_1 
     MOV AH, 9
     INT 21H

     CALL READ                    ; call the procedure READ

     PUSH AX                      ; PUSH AX onto the STACK

     LEA DX, PROMPT_2             ; load and display the string PROMPT_2
     MOV AH, 9
     INT 21H

     POP AX                       ; pop a value from STACK to AX

     @LOOP_1:                     ; loop label
       MOV COUNTER_2, 4           ; set COUNTER_2=4

       @LOOP_2:                   ; loop label
         PUSH AX                  ; push AX onto the STACK

         LEA DX, BLANKS           ; load and display the string BLANKS
         MOV AH, 9                 
         INT 21H                   

         POP AX                   ; pop a value from STACK into AX

         CALL RANDOM              ; call the procedure RANDOM
         CALL WRITE               ; call the procedure WRITE

         DEC COUNTER_2            ; decrement COUNTER_2
         CMP COUNTER_2, 0         ; compare COUNTER_2 with 0
       JNE @LOOP_2                ; jump to label @LOOP_2 if COUNTER_2!=0

       DEC COUNTER_1              ; decrement COUNTER_1
       CMP COUNTER_1, 0           ; compare COUNTER_1 with 0
     JNE @LOOP_1                  ; jump to label @LOOP_1 if COUNTER_1!=0

     MOV AH, 4CH                  ; return control to DOS
     INT 21H
   MAIN ENDP



 ;------------------------  PROCEDURE DEFINITIONS  -------------------------;




 ;---------------------------------  READ  ---------------------------------;


 READ PROC
   ; this procedure will read a number in binary form    
   ; input : none
   ; output : store binary number in AX
   ; uses : MAIN

   JMP @START                     ; jump to label @START

   @AGAIN:                        ; jump label

   LEA DX, AGAIN                  ; load and display the string AGAIN
   MOV AH, 9
   INT 21H

   @START:                        ; jump label

   MOV CX, 16                     ; initialize loop counter
   XOR BX, BX                     ; clear BX
   MOV AH, 1                      ; set input function

   @INPUT:                        ; loop label
     INT 21H                      ; read a character

     CMP AL, 0DH                  ; compare input and CR
     JE @END                      ; jump to label @END if input is CR

     CMP AL, 30H                  ; compare AL with 0
     JL @AGAIN                    ; jump to label @AGAIN if AL<0

     CMP AL, 31H                  ; compare AL with 1
     JG @AGAIN                    ; jump to label @AGAIN if AL>1

     AND AL, 0FH                  ; convert ascii to decimal code
     SHL BX, 1                    ; shift BX by 1 position towards left
     OR  BL, AL                   ; place the input decimal digit in BL
   LOOP @INPUT                    ; jump to label @INPUT if CX!=0

   @END:                          ; jump label

   CMP BX, 0                      ; compare BX with 0
   JLE @AGAIN                     ; jump tolabel if BX<=0

   MOV AX, BX                     ; set AX=BX

   RET                            ; return control to the calling procedure
 READ ENDP


 ;---------------------------------  WRITE  --------------------------------;


 WRITE PROC
   ; this procedure will display a number in binary form    
   ; input : AX  
   ; output : display the binary number in AX
   ; uses : MAIN

   PUSH AX                        ; push AX onto the STACK

   MOV BX, AX                     ; set BX=AX

   MOV CX, 16                     ; initialize loop counter
   MOV AH, 2                      ; set output function

   @OUTPUT:                       ; loop label
     SHL BX, 1                    ; shift BX by 1 position towards left
     JC @ONE                      ; jump to label @ONE if CF=1
     MOV DL, 30H                  ; move 0 to DL
     JMP @DISPLAY                 ; jump tp label @DISPLAY

     @ONE:                        ; jump label
       MOV DL, 31H                ; move 1 to DL

     @DISPLAY:                    ; jump label
       INT 21H                    ; display a digit 
   LOOP @OUTPUT                   ; jump to label @OUTPUT if CX!=0

   POP AX                         ; pop a value from STACK into AX

   RET                            ; return control to the calling procedure
 WRITE ENDP 


 ;---------------------------------  RANDOM  -------------------------------;


 RANDOM PROC
   ; this procedure will generate a random number        
   ; input : AX  
   ; output : AX                                                    
   ; uses : MAIN

   SHL AX, 1                      ; shift AX towards left by 1 position
   XOR DX, DX                     ; clear DX

   TEST AX, 8000H                 ; test the 15-bit of AX
   JNE @FIFTEEN_BIT               ; jump to label @FIFTEEN_BIT if 15-bit=1
   JMP @SKIP_1                    ; jump to label @SKIP_1

   @FIFTEEN_BIT:                  ; jump label
   MOV DH, 1                      ; set DH=1

   @SKIP_1:                       ; jump label

   TEST AX, 4000H                 ; test the 14-bit of AX
   JNE @FOURTEEN_BIT              ; jump to label @FOURTEEN_BIT if 14-bit=1
   JMP @SKIP_2                    ; jump to label @SKIP_2

   @FOURTEEN_BIT:                 ; jump label
   MOV DL, 1                      ; set DL=1

   @SKIP_2:                       ; jump label

   XOR DH, DL                     ; take XOR of DH & DL
   AND AX, 0FFFEH                 ; clear 0-bit of AX
   OR AL, DH                      ; set LSB of AL by XOR of DH & DL
   AND AX, 7FFFH                  ; clear 15-bit of AX

   RET                            ; return control to the calling procedure
 RANDOM ENDP





 END MAIN