data segment
    value db 'SanjaY', '$'
    v_size dw $-value
    val db 7 dup (?)

    upper db 40h
    lower db 60h

data ends

code segment
    assume cs:code, ds:data
begin:
    mov ax, data
    mov ds, ax
    mov es, ax

    lea si, value
    lea di, val
    mov cx, v_size
    dec cx

    mov ah, 09h
    lea dx, valueint 21h

counter:
    mov al, [si]
    cmp al, lower
    jg ltou_case
    jmp utol_case    

ltou_case:
    sub al, 20h
    mov [di], al
    inc si
    inc di
    dec cx
    jnz counter
    jmp exit

utol_case:
    add al, 20h
    mov [di], al
    inc si
    inc di
    dec cx
    jnz counter


exit:
    mov [di], '$'
    mov ah, 09h
    lea dx, val
    int 21h

    mov ax, 4c00h
    int 21h

code ends
end begin