Sunsoft 4 pinout

Sunsoft 4: 40-pin 0.6" PDIP

             .---\/---.                 
       M2 -> | 01  40 | -- +5V                     
  /ROMSEL -> | 02  39 | <- R/W                 
  CPU A14 -> | 03  38 | <- CPU D6                  
  CPU A13 -> | 04  37 | <- CPU D5                  
  CPU A12 -> | 05  36 | <- CPU D4                  
 PPU /A13 -> | 06  35 | <- CPU D3                  
  PPU A12 -> | 07  34 | <- CPU D2                  
  PPU A11 -> | 08  33 | <- CPU D1                  
  PPU A10 -> | 09  32 | <- CPU D0                  
     ?GND -> | 10  31 | <- PPU /RD      
  PRG /CE <- | 11  30 | <- SS4 /CHRSEL  
  CHR A17 <- | 12  29 | -> CHR /CS      
  CHR A16 <- | 13  28 | -> CIRAM /CS    
  CHR A15 <- | 14  27 | -> SS4 /CHRSEL  
  CHR A14 <- | 15  26 | -> WRAM /CE     
  CHR A13 <- | 16  25 | -> CHR A14         
  CHR A12 <- | 17  24 | -> A15          
  CHR A11 <- | 18  23 | -> A16          
  CHR A10 <- | 19  22 | -> A17          
      GND -- | 20  21 | -> WRAM +CE     
             `--------'

10 probably actually some control, not a supply pin
19 also connects to CIRAM A10

Reference: Naruko's notes