Making a cart from scratch...

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the_wizard_666
Posts: 37
Joined: Thu Feb 25, 2021 2:46 pm

Re: Making a cart from scratch...

Post by the_wizard_666 » Fri Mar 26, 2021 6:08 pm

Awesome! Thanks! While I was waiting for a response, I just tried out a different ROM with different chips. I admit to going a bit more advanced than the NROMs I'd done before, choosing to put Dragons of Flame on one of the MMC1 boards. I already knew the ROMs worked fine, so I burned the two ROMs (PRG and CHR), added all the chips, placed caps, diodes and resistors (save for the 27 OHM resistor that Muramasa's board description lists as optional). Solder pads are connected appropriately (CHR ROM is selected instead of CHR RAM, PRG32 is used because it's a 32 pin chip, etc). However, the game does NOT boot. I have not installed a CIC yet, as my lockout is disabled on my main system. The only thing I can think of is possibly a bad WRAM chip, but if my understanding of it is correct that shouldn't affect the game loading, only the ability to save. Another possibility is that I can't see a solder pad for mirroring, but I'm assuming this is because the mapper itself deals with it (Bootgod's database shows that to be the case). Bootgod and Famirom both point to it being an SKROM board, which is confirmed compatible according to Muramasa's product page. I tested the patched ROM, and it works fine, and as far as I can see all my solder points are fine, and nothing is accidentally crossed. Unless the board needs a CIC to boot, which I highly doubt, I can't see a problem that would cause it to simply not load. Any suggestions from the pros?

lidnariq
Posts: 10463
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Location: Seattle

Re: Making a cart from scratch...

Post by lidnariq » Fri Mar 26, 2021 6:37 pm

the_wizard_666 wrote:
Fri Mar 26, 2021 6:08 pm
The only thing I can think of is possibly a bad WRAM chip, but if my understanding of it is correct that shouldn't affect the game loading, only the ability to save.
Due to the reduced amount of memory on the NES console, often games use the extra cart RAM for more than just saving. You may be able to specify a NES2.0 header to disable cart RAM and see if you can get the same crash in an emulator.
Unless the board needs a CIC to boot, which I highly doubt, I can't see a problem that would cause it to simply not load.
No games need the CIC. The top-loader doesn't even have a CIC.

Exactly two games (mapper 37 and mapper 105) are known to use the CIC as a source of a reset pulse, and both are very rare.

the_wizard_666
Posts: 37
Joined: Thu Feb 25, 2021 2:46 pm

Re: Making a cart from scratch...

Post by the_wizard_666 » Fri Mar 26, 2021 8:06 pm

Well, I confirmed the RAM chips are indeed the correct chips, as it turns out my burner can also be used to verify RAM chips (even though they can't do anything WITH those chips). So I confirmed they are the correct chips, so that shouldn't be the problem. I also confirmed while cleaning up a bit that I actually DID buy the 27K ohm resistors, and accidentally used those instead of the 10K ohm ones, so I removed those, put one in the 27K slot, and installed the correct resistors. Sadly, that still didn't fix the problem, as the game simply fails to load. I'm thinking maybe it's an issue with the ROM. If I accidentally burned the wrong file to one of the chips, that could possibly cause the problem. Aside from that, I can't see any obvious problems with anything else. Attached are photos of the board, alongside an unused one for comparison. Like I say, I don't see any obvious issues, none of the contacts are accidentally combined, all the pads are correctly merged to the best of my knowledge...I really don't know what the problem could be aside from possibly burning the wrong files, which I highly doubt I did (but am not gonna rule out until I can desolder the chips to confirm).
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lidnariq
Posts: 10463
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: Making a cart from scratch...

Post by lidnariq » Fri Mar 26, 2021 8:23 pm

Unfortunately, it's really hard to narrow down all the places that something could be wrong, especially when if you don't know that you can trust your PROMs. I'd suggest buying a couple modern 32-pin Flash ROMs and using them with sockets before making more-nearly-permanent reproductions using UVEPROMs.

the_wizard_666
Posts: 37
Joined: Thu Feb 25, 2021 2:46 pm

Re: Making a cart from scratch...

Post by the_wizard_666 » Fri Mar 26, 2021 9:19 pm

You underestimate my determination and sheer stubbornness :lol: The thing is, I already have the stuff and a week off with nothing to do aside from my cousin's funeral, so I'm not too worried about making mistakes - especially ones I can fix in due course. All the boards I've got that didn't work will be stripped, cleaned, and reused, so the only thing it's costing me is time and solder. Practice is what will get me there, and you guys have been great for me when problems do arise. At least, it gets me thinking of things I didn't see before.

I tested my process with a simpler ROM, as my buddy wants a copy of Super Bat Puncher. That one has issues, but actually boots, so at least in that regard I think the problem lies with the files themselves and not the hardware. So while I still need work, I am close to getting it working. Probably shoulda started there instead of a more complex game with a battery, but whatever. I'm confident I can get this going. My buddy has more experience with repros than I, and I'll be heading there tomorrow, so I may have more success with an aide :P

Anyway, I do appreciate everything. I'm definitely making progress in a short span of time, and I'm learning so much here. It may be annoying and old hat to you guys, but it's new and exciting for me. I fully expect a few hiccups along the way, and I appreciate y'all tolerating my newbie mistakes.

lidnariq
Posts: 10463
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: Making a cart from scratch...

Post by lidnariq » Fri Mar 26, 2021 9:36 pm

the_wizard_666 wrote:
Fri Mar 26, 2021 9:19 pm
I tested my process with a simpler ROM, as my buddy wants a copy of Super Bat Puncher. That one has issues, but actually boots, so at least in that regard I think the problem lies with the files themselves and not the hardware.
Super Bat Puncher has been around for a looooooong time now so if you're having problems it's probably the PROMs again.

the_wizard_666
Posts: 37
Joined: Thu Feb 25, 2021 2:46 pm

Re: Making a cart from scratch...

Post by the_wizard_666 » Fri Mar 26, 2021 10:17 pm

Well, with the NROM board, it turned out to be an incompatible chip causing the issues. I'm using 27C010 chips, which should be compatible with the board according to the specs on the website. Basically it's booting up, but with graphical issues, and it freezes after hitting start. The bat animates on the title screen. I've used the PRG32 pads because it's a DIP-32 chip, and the CHR RAM pads.

What I was referring to was that I think that I may have burned the wrong file on the Dragons of Flame cart. Super Bat Puncher only had one file, so there was no way to confuse it, so burning error is something I can safely rule out on that one. Sorry I wasn't so clear on that.

the_wizard_666
Posts: 37
Joined: Thu Feb 25, 2021 2:46 pm

Re: Making a cart from scratch...

Post by the_wizard_666 » Sat Mar 27, 2021 11:22 pm

UPDATE: All issues solved.

Super Bat Puncher required two RAM chips, not just one. Adding that in solved the problem.

Dragons of Flame was indeed a badly burned ROM. I re-burned the chips and it also worked flawlessly.

Moved on up to an MMC3 game and built Destiny of an Emperor 2. Everything works except that the saves keep getting corrupted. 99% sure it's because I don't have a 1000pf capacitor, so I'm gonna order those, add one in, and try again. Aside from that, no issues.

So yeah, all that's left for me to get to testing is the VRC boards, but given that I've solved everything else, I'm not worried anymore. Thanks again for everything, the hardest part seems to be troubleshooting, but now that I know the things I've learned, I don't forsee any more problems, at least until I start doing crazy stuff :p

One quick unrelated question though - I'm considering using an After Burner cart for a Maharaja repro. I'm wondering if I have to rewire the chips like other donors, if it's wired differently, or if no rewiring is necessary. It's not something I'm planning immediately or anything,,, but something I have in my project queue. Thanks!

lidnariq
Posts: 10463
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: Making a cart from scratch...

Post by lidnariq » Sat Mar 27, 2021 11:48 pm

the_wizard_666 wrote:
Sat Mar 27, 2021 11:22 pm
Everything works except that the saves keep getting corrupted. 99% sure it's because I don't have a 1000pf capacitor, so I'm gonna order those, add one in, and try again.
Battery backup is more fragile than other things. The capacitor's absence is a likely culprit, but other things can go wrong too.
One quick unrelated question though - I'm considering using an After Burner cart for a Maharaja repro. I'm wondering if I have to rewire the chips like other donors, if it's wired differently, or if no rewiring is necessary.
If a game was not manufactured by Nintendo, and if a ROM was not exactly 128KB, it usually uses a standard pinout that's compatible with UVEPROMs.

Correspondingly ... if a game used a ROM that was exactly 128KB, it was most often in a 28-pin footprint that will require rewiring. Or if a PCB was manufactured by Nintendo and the PCB could accept a ROM that was 128KB or bigger, if often used Nintendo's own backwards-compatible footprint.

Note that the US release of After Burner only has solder mask on one side, has no place for the save RAM or the extra support hardware for a battery, and uses two 28-pin 128KB mask ROMs for CHR, so reproductions reusing that board definitely counts as "advanced".

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