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tildearrow / furnace

a multi-system chiptune tracker compatible with DefleMask modules
GNU General Public License v2.0
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[Konami Bubble System] Redesign the implementation to be accurate #293

Closed freq-mod closed 2 years ago

freq-mod commented 2 years ago

issue #293: Konami 5289 makes sound. this is physically not possible

The 005289 itself is nothing but an address generator. Digital to analog conversion, volume control and mixing of the channels is all done externally via resistor networks and 4066 switches and is only implemented here for convenience. In short, 5289 REQUIRES AY-3-8910 or compatible to even produce a sound. Therefore, implementation of it must be slightly different:

  1. Implement at as one big pseudo-chip: 2xAY and these 2 chans
  2. (better): have a check: if next to 5289 there is anything but 2x AY/2x8930, no sound is made
iyatemu commented 2 years ago

(better): have a check: if next to 5289 there is anything but 2x AY/2x8930, no sound is made

As anyone getting their hands on (and programming custom software to play their songs on) a real Bubble System is impossible in any practical sense, if the 5289 is implemented, this could be extended to 2x any chip which still has the AY I/O ports.

2xAY + 5289 is the base Bubble System, but hypothetically, a system where two AY8930s are used instead, or two OPNs or OPNAs would still allow the 5289 to be used, while a system with two OPNB/2s would not.

freq-mod commented 2 years ago

ok turns out it DOES use some external logic registers, so invalid