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61 lines
1.6 KiB
NASM

[org 0x7000]
start:
mov [bootdev], dl
mov ah, 06h ; Scroll up function
xor al, al ; Clear entire screen
xor cx, cx ; Upper left corner CH=row, CL=column
mov dx, 184FH ; lower right corner DH=row, DL=column
mov bh, 4Fh ; YellowOnBlue
int 10H ; execute interrupt
mov al, 182 ; meaning that we're about to load
out 43h, al ; prepare speaker for output
mov ax, 2153 ; frequency countdown value is stored in ax. It is calculated by
out 42h, al ; Output low byte.
mov al, ah ; Output high byte.
out 42h, al
in al, 61h
or al, 00000011b
out 61h, al ; Send the new value
; mov bx, 200 ; Pause for duration of note.
mov al, 0
mov ah, 86h
mov cx, 1
mov dx, 200
int 15h
;.pause1:
; mov cx, 65535
;.pause2:
; dec cx
; jne .pause2
; dec bx
; jne .pause1
in al, 61h ; Turn off note (get value from
; port 61h).
and al, 11111100b ; Reset bits 1 and 0.
out 61h, al ; Send new value.
waitforkey:
mov ah, 0x00
int 0x16
cmp ah, 01h
je exit
jmp waitforkey
exit:
in al, 61h ; Turn off note (get value from
; port 61h).
and al, 11111100b ; Reset bits 1 and 0.
out 61h, al ; Send new value.
mov dl, [bootdev]
jmp 0x0:0x1000
bootdev db 0x80 ; Boot device number