VRC2 pinout

The Konami VRC2 and VRC4 chips come in almost-identical 40-pin DIP packages :

• (s) means this pin is shared between rom, system and NES
• (r) this only connects to the ROM
• (n) means this pin is connected to the NES only
• CHR : these connect to the CHR ROM
• PPU : these connect to the PPU
• PRG : these connect to the PRG ROM
• CPU : these connect to the CPU

                  .--\/--. 
   (n) CPU A13 -> |01  40| -- +5V
   (n) CPU A14 -> |02  39| -> PRG A17 (r)
    (s) CPU A1 -> |03  38| -> PRG A15 (r)
    (s) CPU A0 -> |04  37| <- CPU A12 (s)
   (n) PPU A12 -> |05  36| -> PRG A14 (r)
   (n) PPU A11 -> |06  35| -> PRG A13 (r)
   (n) PPU A10 -> |07  34| -> PRG A16 (r)
   (r) PRG /CE <- |08  33| <- CPU D0 (s)
   (n) CPU R/W -> |09  32| <- CPU D1 (s)
   (r) CHR /CE <- |10  31| <- CPU D2 (s)
   (n) PPU A13 -> |11  30| <- CPU D4 (s)
   (n) PPU /OE -> |12  29| <- CPU D3 (s)
   (n) PPU A10 -> |13  28| -> CHR A17 (r)
   (n) /ROMSEL -> |14  27| -> CHR A15 (r)
        (n) M2 -> |15  26| -> CHR A12 (r)
             ? -- |16  25| -> CHR A14 (r)
 VRC4 (n) /IRQ <- |17  24| -> CHR A13 (r)
             ? -- |18  23| -> CHR A11 (r)
 VRC4 WRAM /CE <- |19  22| -> CHR A16 (r)
           GND -- |20  21| -> CHR A10 (r)
                  `------'

On the VRC2, pins 16-19 seem to have been intended for a never-seen-used EEPROM