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
 

Program that starts with an initially undefined byte array of maximum 100, and lets the user insert single characters into the array......

 
 .MODEL SMALL
 .STACK 100H

 .DATA
   ARRAY  DB  100 DUP(?)

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

     LEA SI, ARRAY                ; set SI=offset address of variable ARRAY
     XOR BX, BX                   ; clear BX

     @INPUT:                      ; loop label
       MOV AH, 2                  ; set output function
       MOV DL, \"?\"                ; set DL=\"?\"
       INT 21H                    ; print a character

       MOV AH, 1                  ; set input function
       INT 21H                    ; read a character

       CMP AL, 1BH                ; compare AL with <ESC>
       JE @END_INPUT              ; jump to label @END_INPUT if AL=<ESC>

       MOV CX, BX                 ; set CX=BX
       JCXZ @NOT_PRESENT          ; jump to label @NOT_PRESENT if CX=0

       PUSH SI                    ; push SI onto the STACK
       LEA SI, ARRAY              ; set SI=offset address of variable ARRAY

       @COMPARE:                  ; loop label
         MOV DL, [SI]             ; set DL=[SI]

         CMP AL, DL               ; compare AL with DL
         JE @ALREADY_PRESENT      ; jump to label @ALREADY_PRESENT if AL=DL

         INC SI                   ; set SI=SI+1
       LOOP @COMPARE              ; jump to label @COMPARE while CX!=0

       JMP @NOT_PRESENT           ; jump to label @NOT_PRESENT

       @ALREADY_PRESENT:          ; jump label
       POP SI                     ; pop a value from STACK into SI
       JMP @SKIP_INPUT            ; jump to label @SKIP_INPUT

       @NOT_PRESENT:              ; jump label
       INC BX                     ; set BX=BX+1
       MOV [SI], AL               ; set [SI]=AL
       INC SI                     ; set SI=SI+1

       @SKIP_INPUT:               ; jump label

       MOV AH, 2                  ; set output function
       MOV DL, 0DH                ; carriage return 
       INT 21H                    

       MOV DL, 0AH                ; line feed
       INT 21H                    

       PUSH SI                    ; push SI onto the STACK

       LEA SI, ARRAY              ; set SI=offset address of varibale ARRAY

       CALL BUBBLE_SORT           ; call the procedure BUBBLE_SORT

       LEA SI, ARRAY              ; set SI=offset address of varibale ARRAY

       CALL PRINT_ARRAY           ; call the procedure PRINT_ARRAY

       POP SI                     ; pop a value from STACK into SI

       MOV AH, 2                  ; set output function
       MOV DL, 0DH                ; carriage return
       INT 21H                    

       MOV DL, 0AH                ; line feed
       INT 21H                    

       JMP @INPUT                 ; jump to label @INPUT

     @END_INPUT:                  ; jump label

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



 ;-------------------------  Procedure Definitions  ------------------------;




 ;-----------------------------  PRINT_ARRAY  ------------------------------;


 PRINT_ARRAY PROC
   ; this procedure will print the elements of a given array
   ; input : SI=offset address of the array
   ;       : BX=size of the array
   ; output : none

   PUSH AX                        ; push AX onto the STACK
   PUSH CX                        ; push CX onto the STACK
   PUSH DX                        ; push DX onto the STACK

   MOV CX, BX                     ; set CX=BX
   MOV AH, 2                      ; set output function

   @PRINT_ARRAY:                  ; loop label
     MOV DL, [SI]                 ; set DL=[SI]
     INT 21H                      ; print a character

     INC SI                       ; set SI=SI+1
   LOOP @PRINT_ARRAY              ; jump to label @PRINT_ARRAY while CX!=0

   POP DX                         ; pop a value from STACK into DX
   POP CX                         ; pop a value from STACK into CX
   POP AX                         ; pop a value from STACK into AX

   RET                            ; return control to the calling procedure
 PRINT_ARRAY ENDP


 ;----------------------------  BUBBLE_SORT  -------------------------------;


 BUBBLE_SORT PROC
   ; this procedure will sort the array in ascending order
   ; input : SI=offset address of the array
   ;       : BX=array size
   ; output : none

   PUSH AX                        ; push AX onto the STACK  
   PUSH BX                        ; push BX onto the STACK
   PUSH CX                        ; push CX onto the STACK
   PUSH DX                        ; push DX onto the STACK
   PUSH DI                        ; push DI onto the STACK

   MOV AX, SI                     ; set AX=SI
   MOV CX, BX                     ; set CX=BX

   CMP CX, 1                      ; compare CX with 1
   JLE @SKIP_SORTING              ; jump to label @SKIP_SORTING if CX<=1

   DEC CX                         ; set CX=CX-1

   @OUTER_LOOP:                   ; loop label
     MOV BX, CX                   ; set BX=CX
     MOV SI, AX                   ; set SI=AX
     MOV DI, AX                   ; set DI=AX
     INC DI                       ; set DI=DI+1

     @INNER_LOOP:                 ; loop label 
       MOV DL, [SI]               ; set DL=[SI]

       CMP DL, [DI]               ; compare DL with [DI]
       JNG @SKIP_EXCHANGE         ; jump to label @SKIP_EXCHANGE if DL<[DI]

       XCHG DL, [DI]              ; set DL=[DI], [DI]=DL
       MOV [SI], DL               ; set [SI]=DL

       @SKIP_EXCHANGE:            ; jump label
       INC SI                     ; set SI=SI+1
       INC DI                     ; set DI=DI+1

       DEC BX                     ; set BX=BX-1
     JNZ @INNER_LOOP              ; jump to label @INNER_LOOP if BX!=0
   LOOP @OUTER_LOOP               ; jump to label @OUTER_LOOP while cX!=0

   @SKIP_SORTING:                 ; jump label

   POP DI                         ; pop a value from STACK into DI
   POP DX                         ; pop a value from STACK into DX
   POP CX                         ; pop a value from STACK into CX
   POP BX                         ; pop a value from STACK into BX
   POP AX                         ; pop a value from STACK into AX

   RET                            ; return control to the calling procedure
 BUBBLE_SORT ENDP





 END MAIN

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