This is the code: 

```
push ax
in al, 0x61
or al, 0x80  ; 10000000b
out 0x61, al
and al, 0x7F ; 01111111b
out 0x61, al
mov al, 0x20
out 0x20, al
pop ax

```

What does it do? I only know its connected to the timer interrupt. What's on `0x61` and `0x20`?