I've been trying to make a repro of this pirate game for some time without success.
Here's what I've done so far:
I took a look on this game's board on this thread.
Unfortunatelly I couldn't find a schematics, so with information from various posts and the wiki, I tried to imagine how it should be and ended with this schematic: Not totally sure if this is 100% correct.
Since I didn't have all the parts to build just as in the schematics, I tried to convert an UNROM board like this:
Code: Select all
74LS02 ____ 74LS138 74LS74 PPU A10--\ \ ____ +---V---+ +------+ ) O----\ \ CPU A13-1|A0 |16---VCC---1|CLR Q|5----------/___/ ) O---CIRAM A10 CPU A14-2|A1 O0|15---------3|CLK | ____ +---/___/ /ROMSEL-3|A2 O1|14 CPU D0-2|D | PPU A11--\ \ | /ROMSEL-4|/E0 O2|13 VCC---4|PRE /Q|6-+ ) O+ CPU R/W-5|/E1 O3|12-+ +------+ +--------/___/ M2-6|E2 O4|11 | 7|O7 O5|10 | 74LS32 GND-8|8 O6| | ____ +-------+ | 74LS161 CPU A14--\ \ | +---V---+ ) )---PRG A14 +-2|CLK QA|14--------/___/ CPU D0--3|A | ____ CPU D1--4|B QB|13--------\ \ CPU D2--5|C | ) )---PRG A15 6|D | CPU A14--/___/ GND--7|ENP | ____ GND--10|ENT QC|12--------\ \ CPU R/W--9|/LD | ) )---PRG A16 VCC---1|CLR | CPU A14--/___/ +-------+
Basically I unplugged the pin 2 of the 74'161 and had plugged it on the circuit composed of the 74'138, 74'74 and 74'02, after plugging the other pins on the respective spots on the board. So the UNROM part was working fine before and is almost untouched.
And them comes my first doubt: are these schematics correct?
Assuming the last schematic is correct, I proceeded and assembled the board.
I used to it the following NES ROM:
Code: Select all
Highway Star (Kaiser)[U][!].nes CRC32: e6416634
But unfourtunatelly the thing didn't work as expected.
And here comes my second doubt: is that the correct ROM for this mapper?
I tried Holy Maperel on the modified PCB and it showed it as UNROM, as expected.
I had dumped the ROM and it was identical to the one I had written to it.
I tried some UNROM games on the modified board and none booted, just had shown a black screen or a coloured screen with an "walking" stripe from the top to the bottom of the screen, wich probably means that at least the last bank is in the correct place, right?
I've reviewd the schematics and the big mess that the modified PCB had become and found nothing wrong, unless of course, the schematics are wrong.
Can someone please help me?
Thanks in advance.