YM2612 - EG timing

For anything related to sound (YM2612, PSG, Z80, PCM...)

Moderator: BigEvilCorporation

Post Reply
Michel Gerritse
Posts: 8
Joined: Sat Apr 25, 2020 7:25 pm
Location: The Netherlands

YM2612 - EG timing

Post by Michel Gerritse » Tue Feb 22, 2022 9:06 pm

So I finally took some time to create an Excel sheet with all the envelope timing (decay only at the moment) given by the FM Towns datasheet. In case you are wondering, the FM Towns uses a YM2612 and their documentation is very complete (but in Japanese).

You can find the Excel sheet here:
https://github.com/michelgerritse/YM-re ... mings.xlsx

Basically this all confirms the envelope timing MAME and Nemesis already figured out by analyzing actual recordings. Nemesis' post about this can be found here:
http://gendev.spritesmind.net/forum/vie ... 5716#p5716

However, there are 2 exceptions to their findings: When the calculated rate value is 2 or 3.
The FM Towns docs doesn't give timing for rate values 0, 1, 2 and 3 as they are considered infinite. Nemesis states that only rate 0 and 1 are infinite.
I would really like to get this confirmed from actual recordings but I don't have the hardware to do so.

Note: rate value 8 is suspicious for being a type in the FM Towns docs.

Can someone give a definitive answer on this ?

Post Reply