The "Envelope Speed" section has this quote:
- BIOS or game code appears to set this to $FF.
I've recently checked the FDS bios disassembly, and it seems to actually set the value to $E8, as seen at $ee72 in the BIOS:
$EE72 LDA #$e8 $EE74 STA $408A
FDS games may set the envelope speed to $FF; However, I haven't checked any of them, so I wouldn't be able to tell you. --Freem 20:47, 12 January 2013 (MST)