A friend of mine asked me to do a repro of a NROM game he bought.
Since it's a commercial game that's being sold, I think it's better to not post the ROMs or pictures.
He bringed me this UNROM PCB: So far so good, the ROM pins are swapped.
I took a look and it seems to be like this:
Code: Select all
PRG ROM
+---V---+ 6264
NC |1 32| Vcc CHR RAM
A16 |2 31| Vcc +---V---+
A15 |3 30| Vcc Vcc |1 28| Vcc
A12 |4 29| A14 A7 |2 27| R/W
A7 |5 28| A13 A8 |3 26| Vcc
A6 |6 27| A11 A6 |4 25| A9
A5 |7 26| A10 A5 |5 24| A11
A4 |8 25| A9 A4 |6 23| A10
A3 |9 24| /ROMSEL A3 |7 22| PPU /RD
A2 |10 23| A8 A2 |8 21| A12
A1 |11 22| GND A1 |9 20| PPU A13
A0 |12 21| D7 A0 |10 19| D7
D2 |13 20| D6 D0 |11 18| D6
D0 |14 19| D5 D1 |12 17| D5
D1 |15 18| D4 D2 |13 16| D4
GND |16 17| D3 GND |14 15| D3
+-------+ +-------+
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PRG:
pinswap -a16,15,14,13,12,9,8,10,11,7,6,5,4,3,2,1,0 -d7,6,5,4,3,1,0,2 -o sw-prg.bin prg.bin
CHR:
pinswap -a7,10,12,11,9,8,6,5,4,3,2,1,0 -o sw-chr.bin chr.bin
I used a 27c128 for the CHR, doubling the data after pinswaping and putting the A13 pin to VCC.
I just can't figure out what's wrong, I reviewed the pinout, the parameters and the soldering a dozen of times without success.
Can someone please suggest something I could do to solve this problem?
Thanks in advance.