Assembly Language Tutorial



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
 .STACK 100H

   PROMPT  DB  \'Current System Time is : $\'     
   TIME    DB  \'00:00:00$\'        ; time format hr:min:sec

     MOV AX, @DATA                ; initialize DS
     MOV DS, AX

     LEA BX, TIME                 ; BX=offset address of string TIME

     CALL GET_TIME                ; call the procedure GET_TIME

     LEA DX, PROMPT               ; DX=offset address of string PROMPT
     MOV AH, 09H                  ; print the string PROMPT
     INT 21H                      

     LEA DX, TIME                 ; DX=offset address of string TIME
     MOV AH, 09H                  ; print the string TIME
     INT 21H                      

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

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

 ;------------------------------  GET_TIME  --------------------------------;

    ; this procedure will get the current system time 
    ; input : BX=offset address of the string TIME
    ; output : BX=current time

    PUSH AX                       ; PUSH AX onto the STACK
    PUSH CX                       ; PUSH CX onto the STACK 

    MOV AH, 2CH                   ; get the current system time
    INT 21H                       

    MOV AL, CH                    ; set AL=CH , CH=hours
    CALL CONVERT                  ; call the procedure CONVERT
    MOV [BX], AX                  ; set [BX]=hr  , [BX] is pointing to hr
                                  ; in the string TIME

    MOV AL, CL                    ; set AL=CL , CL=minutes
    CALL CONVERT                  ; call the procedure CONVERT
    MOV [BX+3], AX                ; set [BX+3]=min  , [BX] is pointing to min
                                  ; in the string TIME

    MOV AL, DH                    ; set AL=DH , DH=seconds
    CALL CONVERT                  ; call the procedure CONVERT
    MOV [BX+6], AX                ; set [BX+6]=min  , [BX] is pointing to sec
                                  ; in the string TIME

    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
   GET_TIME ENDP                  ; end of procedure GET_TIME

 ;-------------------------------  CONVERT  --------------------------------;

    ; this procedure will convert the given binary code into ASCII code
    ; input : AL=binary code
    ; output : AX=ASCII code

    PUSH DX                       ; PUSH DX onto the STACK 

    MOV AH, 0                     ; set AH=0
    MOV DL, 10                    ; set DL=10
    DIV DL                        ; set AX=AX/DL
    OR AX, 3030H                  ; convert the binary code in AX into ASCII

    POP DX                        ; POP a value from STACK into DX 

    RET                           ; return control to the calling procedure
   CONVERT ENDP                   ; end of procedure CONVERT


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