MC-ACC pinout
MC-ACC chip: (40-pin 0.6" DIP)
.--\/--.
GND ?? |01 40| -- 5V
(r) PRG A16 <- |02 39| -> PRG A18 (r)
(r) PRG A15 <- |03 38| -> PRG A17 (r)
(n) CPU A14 -> |04 37| -> PRG A14 (r)
(n) CPU A13 -> |05 36| -> PRG A13 (r)
n/c ?? |06 35| <- CPU R/W (n)
n/c ?? |07 34| <- /ROMSEL (n)
n/c ?? |08 33| -> PRG /OE (r)
(nr) CPU A0 -> |09 32| <- CPU D7 (nr)
(nr) CPU D0 -> |10 31| <- CPU D6 (nr)
(nr) CPU D1 -> |11 30| <- CPU D5 (nr)
(nr) CPU D2 -> |12 29| <- CPU D4 (nr)
(r) CHR A16 <- |13 28| <- CPU D3 (nr)
(r) CHR A15 <- |14 27| -> CIRAM A10 (n)
(r) CHR A14 <- |15 26| -> CHR A17 (r)
(r) CHR A13 <- |16 25| -> /IRQ (n)
(r) CHR A12 <- |17 24| <- PPU A12 (n)
(r) CHR A11 <- |18 23| <- PPU A11 (n)
(r) CHR A10 <- |19 22| <- PPU A10 (n)
GND -- |20 21| <- M2 (n)
'------'
39: confirmed in [1]
24: on the 55741 PCB, deglitched and shaped as MCACCA12IN = AND(PPUA12,AND(AND(AND(PPUA12)))). Kevtris's notes
Source: https://forums.nesdev.org/viewtopic.php?p=16795#p16795