PPUCTRL = $2000
PPUMASK = $2001
PPUSTATUS = $2002
OAMADDR = $2003
OAMDATA = $2004
PPUSCROLL = $2005
PPUADDR = $2006
PPUDATA = $2007
OAMDMA = $4014
SND_CHN = $4015
JOY1 = $4016
JOY2 = $4017