MMC5 pinout

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                                                   _____
                                                  /     \
                        Audio Amplifier Input -> / 1 100 \ -> Audio Amplifier Output
                                   Audio DAC <- / 2    99 \ -- AGnd
                          Audio Pulse Waves <- / 3  (*) 98 \ <> SL3
                                  +5V AVcc -- / 4        97 \ <> CL3
                              (fr) PPU A0 -> / 5          96 \ -> CHR A2 †
                             (fr) PPU A1 -> / 6            95 \ -> CHR A1 †
                            (fr) PPU A2 -> / 7              94 \ -> CHR A0 †
                           (fr) PPU A3 -> / 8                93 \ -> PRG RAM A15 (R)
                          (fr) PPU A4 -> / 9                  92 \ ?? (unknown input)
                         (fr) PPU A5 -> / 10                   91 \ <> PPU D7 (fr)
                        (fr) PPU A6 -> / 11                     90 \ <> PPU D6 (fr)
                       (fr) PPU A7 -> / 12                       89 \ <> PPU D5 (fr)
                      (fr) PPU A8 -> / 13                         88 \ <> PPU D4 (fr)
                     (fr) PPU A9 -> / 14                           87 \ <> PPU D3 (fr)
                    (r) CHR A10 <- / 15                             86 \ <> PPU D2 (fr)
                   (r) CHR A11 <- / 16                               85 \ <> PPU D1 (fr)
                  (r) CHR A12 <- / 17                                 84 \ <> PPU D0 (fr)
                 (r) CHR A13 <- / 18                                   83 \ -> PRG RAM +CE (R)
                (r) CHR A14 <- / 19                                     82 \ ?? (unknown input)
               (r) CHR A15 <- / 20                                       81 \ ?? (unknown input)
              (r) CHR A16 <- / 21                                            \
             (r) CHR A17 <- / 22                                             /
            (r) CHR A18 <- / 23                                          80 / -- DGnd
           (r) CHR A19 <- / 24                                          79 / <- M2 (f)
          (f) PPU A10 -> / 25                                          78 / <- /ROMSEL (f)
         (f) PPU A11 -> / 26              Nintendo MMC5               77 / <- CPU R/W (f)
        (f) PPU A12 -> / 27      Package QFP-100, 0.65mm pitch       76 / -> PRG RAM /WE (R)
      (f) PPU /A13 -> / 28                                          75 / -> PRG RAM /CE (RAM0/CE & RAM1/CE) (R)
  (unknown input) ?? / 29                                          74 / -> PRG /CE (r)
 (unknown input) ?? / 30                                          73 / -> PRG RAM A16 (R)
                   /                                             72 / -> PRG RAM 1 /CE (R)
                   \                                            71 / -> PRG RAM 0 /CE (R)
   (f) CIRAM /CE <- \ 31                                       70 / -> PRG RAM A14 (R)
    (f) CIRAM A10 <- \ 32                                     69 / -> PRG RAM A13 (R)
       (f) PPU /WR -> \ 33                                   68 / <- CPU A14 (f)        Orientation:
        (f) PPU /RD -> \ 34                                 67 / <- CPU A13 (f)         --------------------
            (f) /IRQ <- \ 35                               66 / -> PRG A19 (r)              80         51
         (frR) CPU D0 <> \ 36                             65 / -> PRG A18 (r)                |         |
          (frR) CPU D1 <> \ 37                           64 / -> PRG A17 (r)                .-----------.
           (frR) CPU D2 <> \ 38                         63 / -> PRG A16 (r)              81-| Nintendo o|-50
            (frR) CPU D3 <> \ 39                       62 / -> PRG A15 (r)                  | MMC5      |
             (frR) CPU D4 <> \ 40                     61 / -> PRG A14 (r)               100-|@          |-31
              (frR) CPU D5 <> \ 41                   60 / -> PRG A13 (r)                    \-----------'
               (frR) CPU D6 <> \ 42                 59 / <- CPU A12 (frR)                    |         |
                (frR) CPU D7 <> \ 43               58 / <- CPU A11 (frR)                   01         30
                     +5V DVcc -- \ 44             57 / -- + Backup battery
                  (frR) CPU A0 -> \ 45           56 / -> PRG RAM Vcc Output   Legend:
                   (frR) CPU A1 -> \ 46         55 / <- CPU A10 (frR)         ------------------------------
                    (frR) CPU A2 -> \ 47       54 / <- CPU A9 (frR)           --[MMC5]-- Power
                     (frR) CPU A3 -> \ 48  O  53 / <- CPU A8 (frR)            ->[MMC5]<- MMC5 input
                      (frR) CPU A4 -> \ 49   52 / <- CPU A7 (frR)             <-[MMC5]-> MMC5 output
                       (frR) CPU A5 -> \ 50 51 / <- CPU A6 (frR)              <>[MMC5]<> Bidirectional
                                        \     /                               ??[MMC5]?? Unknown
                                         \   /                                    f      Famicom connection
                                          \ /                                     r      ROM chip connection
                                           V                                      R      RAM chip connection

† PINS 96 thru 98: These set the cart to either CL or SL mode.

To set to CL mode:

  • Connect PPU A0 from the NES to A0 on the CHR ROM.
  • Connect PPU A1 from the NES to A1 on the CHR ROM.
  • Connect PPU A2 from the NES to A2 on the CHR ROM.
  • Leave pins 94,95 & 96 floating on the MMC5

To set to SL mode:

  • Connect pin 94 of the MMC5 to A0 of the CHR ROM.
  • Connect pin 95 of the MMC5 to A1 of the CHR ROM.
  • Connect pin 96 of the MMC5 to A2 of the CHR ROM.

In other words, CL mode passes the lowest PPU address bits straight to CHR ROM, while SL mode runs them through MMC5. SL mode allows the MMC5 to perform smooth vertical scrolling in split mode, while CL mode does not. Nearly all MMC5 cartridges use CL mode - it is not known why SL mode was not used instead: possibly ROM speed issues.

Audio circuit topology for HVC-ExROM boards:

MMC5 audio.png