INES Mapper 085

iNES Mapper 085 is used to represent the Konami VRC7 mapper.

 Here are Disch's original notes:
 ========================
 =  Mapper 085          =
 ========================
 
 aka
 --------------------------
 VRC7
 
 
 Example Games:
 --------------------------
 Lagrange Point
 Tiny Toon Adventures 2  (J)
 
 
 
 VRC7a vs. VRC7b
 --------------------------
 Lagrange Point ('VRC7a') and Tiny Toon Adventures 2 ('VRC7b') both operate exactly the same, but are wired a
 bit differently.  VRC7a uses $x010 for regs, and VRC7b uses $x008.  Registers below are listed as they exist
 on VRC7a.  For VRC7b, make the appropriate adjustments
 
 Also, only Lagrange Point seems to use the extra sound.  It's unknown whether or not the sound hardware
 exists on VRC7b, as Tiny Toon doesn't use it.
 
 
 CHR-RAM note:
 --------------------------
 Lagrange Point, for some reason I still don't understand, swaps its 8k CHR-RAM around.  How this offers any
 functionality is beyond me, but the game does it, so your emu must support it.
 
 
 
 Registers:
 --------------------------
 
 $8000:   PRG Reg 0  (8k @ $8000)
 $8010:   PRG Reg 1  (8k @ $A000)
 $9000:   PRG Reg 2  (8k @ $C000)
 
 $9010:   Sound Address Reg (see below)
 $9030:   Sound Data Port (see below)
 
 $A000-$D010:  CHR Regs
 
 $E000:   [.... ..MM]   Mirroring:
        %00 = Vert
        %01 = Horz
        %10 = 1ScA
        %11 = 1ScB
 
 $E010:   [IIII IIII]   IRQ Reload value
 $F000:   [.... .MEA]   IRQ Control
 $F010:   [.... ....]   IRQ Acknowledge
 
 
 PRG Setup:
 --------------------------
 
       $8000   $A000   $C000   $E000  
     +-------+-------+-------+-------+
     | $8000 | $8010 | $9000 | { -1} |
     +-------+-------+-------+-------+
 
 
 CHR Setup:
 --------------------------
 
       $0000   $0400   $0800   $0C00   $1000   $1400   $1800   $1C00 
     +-------+-------+-------+-------+-------+-------+-------+-------+
     | $A000 | $A010 | $B000 | $B010 | $C000 | $C010 | $D000 | $D010 |
     +-------+-------+-------+-------+-------+-------+-------+-------+
 
 
 IRQs:
 --------------------------
 
 VRC7 uses the "VRC IRQ" setup shared by several VRCs.  It uses the following registers:
 
 
   $E010:   [IIII IIII]   IRQ Reload
   $F000:   [.... .MEA]   IRQ Control
   $F010:   [.... ....]   IRQ Acknowledge
 
 For info on how these IRQs work, see the "VRC IRQs" section in mapper 021
 
 
 
 Sound:
 --------------------------
 
 VRC7 has additional sound channels!  It is a slightly dumbed down version of the YM2413 (aka OPLL).  There
 are only 6 harmony channels and no rhythmic channels.  Note that some older docs claim it's an OPL2 -- but it
 is, in fact, OPLL.
 
 Due to the complexity of FM-synth ... details will not be covered here.  For details, refer to a YM2413 data
 sheet or technical doc.
 
   $9010 is the address port
   $9030 is the data port
 
   They behave just like the address/data ports on the YM2413.  Though remember that there's no rhythm, and
 only 6 channels.
 
 Channels can choose from 16 instruments.  One is customizable by the game, the other 15 are fixed with the
 following values:
 
 {
 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,  // custom instrument
 
 0x03,0x21,0x04,0x06,0x8D,0xF2,0x42,0x17,  // begin fixed instruments
 0x13,0x41,0x05,0x0E,0x99,0x96,0x63,0x12,
 0x31,0x11,0x10,0x0A,0xF0,0x9C,0x32,0x02,
 0x21,0x61,0x1D,0x07,0x9F,0x64,0x20,0x27,
 0x22,0x21,0x1E,0x06,0xF0,0x76,0x08,0x28,
 0x02,0x01,0x06,0x00,0xF0,0xF2,0x03,0x95,
 0x21,0x61,0x1C,0x07,0x82,0x81,0x16,0x07,
 0x23,0x21,0x1A,0x17,0xEF,0x82,0x25,0x15,
 0x25,0x11,0x1F,0x00,0x86,0x41,0x20,0x11,
 0x85,0x01,0x1F,0x0F,0xE4,0xA2,0x11,0x12,
 0x07,0xC1,0x2B,0x45,0xB4,0xF1,0x24,0xF4,
 0x61,0x23,0x11,0x06,0x96,0x96,0x13,0x16,
 0x01,0x02,0xD3,0x05,0x82,0xA2,0x31,0x51,
 0x61,0x22,0x0D,0x02,0xC3,0x7F,0x24,0x05,
 0x21,0x62,0x0E,0x00,0xA1,0xA0,0x44,0x17
 };