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Weirdness with the Prototype Sonic 1 Sound Driver

Discussion in 'Engineering & Reverse Engineering' started by Alex Field, Feb 18, 2021.

  1. For those who don't understand the thread title, this is about all the strange oddities that the sound drive in the Sonic 1 prototype has; this was made before they tuned it to their liking, though quite frankly, some of the changes they made were surprising.
    • The WriteFMI and WriteFMII functions (sub_7272E/sub_72764) are the Type 1b versions, which the Sonic 1 sound driver is based on, EXCEPT that they went back to an (unoptimized) Type 1a version.
    • Has several more features, meaning this driver is superior to the final (again, it was tuned to their liking meaning some features were removed since they were unneeded).
    • Handles sound IDs <$80 in a different (and faster) way, which also makes support for music <$80 easier.
    • Although it can't be heard normally, there is a special function for sounds $D7>$DF which causes it to play a DAC sample ($D7=$81/Kick, $D8=$82/Snare etc...).
    • Handles music tempo differently, though the actual outcome is the same.
    Last edited: Feb 18, 2021