> > Apparently some of the bootlegs of both this and Phoenix used different doorbell
> > chips too?
>
> There is a Atari Tetris bootleg that uses an additional Z80 and a UM3482 for sound (a
> doorbell chip).
>
> Sean decapped my UM3482 and the bits are clearly visible, but we cannot make sense of
> them (we cannot find the logical order). There is no CPU core on it, and there are
> four ROM regions, one for notes, other for the offset of each doorbell melody and the
> other two are for unknown purpose.
>
> Sean even captured the output of the chip with a logic analyzer while it played all
> 12 songs, then wrote a program to measure the period of each note and count the
> number of cycles it was played... But still we're missing something.
might be worth making that data public?
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