.model small
.stack
.data
sir db 'A', 41h, 'B', 24h, 'C', 0C9h, 'D', 0AFh, 'E', 0FAh
car db '*'
note dw 0 
freq dw 260
msg db '...tone generated','$'
msgKey db 10,13,'press any key in order to quit the program', '$'
msgLast db 10,13,'done','$'
.code

main:
mov ax, @data
mov ds, ax

mov AL, 00000010b
out 21h, AL

mov ax,351Ch
int 21h								
push ES		
push BX	
	
push DS
mov AX,SEG isr1Ch
mov DS,AX
mov DX,OFFSET isr1Ch
mov AL,1Ch
mov AH,25h
int 21h
pop DS

mov note, 11930 /260  *100

mov AX, 3
int 10h     
mov AX, 0B832h
mov ES, AX
mov DI, 3999 ; start from the last row
mov SI, 0
mov cx, 10

eti:
mov AL, sir[SI]
mov ES:[DI], AL
inc SI
dec DI ; decrement the index to display letters from bottom to top
push si

mov SI, 5000/55/5              
sub note, 350

loop eti

mov AH, 0Eh
mov AL, '$' 
int 10h
mov AH, 0Eh
mov AL, msg[0]
int 10h
mov AH, 0Eh
mov AL, msg[1]
int 10h
mov AH, 0Eh
mov AL, msg[2]
int 10h

mov AH, 0Eh
mov AL, msgKey[0]
int 10h
mov AH, 0Eh
mov AL, msgKey[1]
int 10h
mov AH, 0Eh
mov AL, msgKey[2]
int 10h
mov AH, 0Eh
mov AL, msgKey[3]
int 10h
mov AH, 0Eh
mov AL, msgKey[4]
int 10h
mov AH, 0Eh
mov AL, msgKey[5]
int 10h

mov AH, 0
int 16h

mov AH, 0Eh
mov AL, msgLast[0]
int 10h
mov AH, 0Eh
mov AL, msgLast[1]
int 10h
mov AH, 0Eh
mov AL, msgLast[2]
int 10h

mov AH, 4Ch
mov AL, 00h
int 21h

isr1Ch proc near
push ax
push bx
push cx
push dx
in al, 61h
or al, 00000011b
out 61h, al
mov al, 0B6h
out 43h, al
mov ax,word ptr freq
out 42h, al
mov al