Assembly-Programming/11. ASCII EQUIVALENT DECIMAL.asm at main · rng70/Assembly-Programming · GitHub

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; READ A ASCII CHARACTER A-F
; THEN DISPLAY AS DECIMAL

; ASCII OF A-F IS 41H-46H
; ASCII OF 0 IS 30H
; THE DIFFERENCE IS 11H
; SO WHEN WE SUBTRACT 11H FROM THE INPUT DIGIT WE GOT THE LAST DIGIT EQUIVALENT
; TO IT'S DECIMAL REPRESENTATION
; SO IN MSG2 WE ADDED A 1 BEFORE PRINTING THE VALUE
; THAT'S GIVES US THA RESULT

    ; ASCII OF A --> 41H
    ; SUBTRACT   --> 11H

    ;--------------------

    ; RESULT     --> 30H

    ; ASCII OF 0 --> 30H

    ; ADDING A '1' BEFORE THE RESULT WE HAVE 10
    ; WHICH IS EQUIVALENT OF A AS A=10H
    ; SO WE INCLUDED '1' IS THE SECOND MESSAGE


.MODEL SMALL

.STACK 100H

.DATA
    MSG DB 'ENTER A HEX DIGIT: $'
    MSG2 DB 0AH, 0DH, 'IN DECIMAL IT IS 1'

    C1 DB ?, '$'

.CODE
    MAIN PROC

        ; INITIALIZE DS

        MOV AX, @DATA
        MOV DS, AX

        ; DISPLAY THE MESSAGE
        MOV AH, 9
        LEA DX, MSG
        INT 21H

        ; TAKE INPUT
        MOV AH, 1
        INT 21H

        SUB AL, 11H

        ; STORE
        MOV C1, AL

        MOV AH, 9
        LEA DX, MSG2
        INT 21H

        ; DOS EXIT
        MOV AH, 4CH
        INT 21H

    MAIN ENDP

END MAIN