> > 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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