The Skinny on GB sound
By Aaron St. John
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Before you read this document, be sure to grab the gbsnd2 document (available from http://www.gbdev.org/news/dl.html) and have it read it through.  This document gives hints to using sound, not a thorough explanation!

Rule #1:

	Thou shalt bow to the almighty NR_52 register!  Without this register your GameBoy sound is nothing.  You may not realize it, but if bit 7 of NR_52 (all sound on/off) is not set, the real GB will not accept any changes to any sound registers.  Just because an emulator let's you set other sound registers doesn't mean the real GB will.

BAD:						GOOD:
Setting the regs in this order:	Using this order:
NR_50						NR_52
NR_51						NR_50
NR_52						NR_51

Rule #2:

	Thou shalt re-set the envelope/tone registers every time you play a new sound.  Don't that just because you told the GB what envelope/freq/length to use last time you started a sound that the right values will be there again.  From what I can tell, the GB updates the envelope/freq/length regs every on-the-fly as it is playing a sound.  Just be safe, set the envelope/freq/length regs before you set the initial reg.

Rule #3: 

	Thou shalt never use VIN (bits 7 and 3 of NR_50).  VIN is made so that you can pump sounds through the cartridge pins into the GB.  As a homebrew coder, you'll probably never need to use VIN, so keep those bits off.  Things will just be generally nicer for you.

Rule #4:

	UM, haven't thought of one yet.