Description

Semester: V

Experiment No. 8: Case conversion

Input: letters through keyboard
Output: case converted letters on the fly

Hint:

Use dos interrupt 21H with AH=01 to read the letters with echo
Use AH=2 to display the letters to standard output device

Program

ASSUME CS:CODE,DS:data data SEGMENT COUNT equ 10h data ends
CODE SEGMENT
START:MOV AX,data
MOV DS,AX
MOV CX,COUNT ; LOOP COUNTER
L1:MOV AH,1 ; INPUT CHARACTER,
INT 21H ; AL = CHARACTER, ASCII(hex) :A-Z=41-5A, a-z=61-7A
CMP AL,60H
JNC UPPER
ADD AL,20H
JMP SKIP
UPPER:SUB AL,20H ; CONVERT TO UPPER CASE
SKIP:MOV AH,2 ; CHARACTER OUTPUT FUNCTION
MOV DL,AL ; CHARACTER MUST BE IN DL
INT 21H ; DISPLAY THE CHARACTER
LOOP L1 ; REPEAT LOOP
MOV Ah,4CH
INT 21H
CODE ENDS
end start