UNROM to UOROM conversion

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SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

UNROM to UOROM conversion

Post by SheriffTodd » Wed Apr 28, 2021 4:17 pm

Howdy folks!

I'm new to these here parts and I'm fixin' on making a translated Law of the West on silicon and copper.

Now I reckon yall are some of the best and brightest this side of the...okay I'll stop now.

So the translation is a 256KB PRG and FamiROM identifies the patched rom file as a UOROM (or UNROM*...idk what that means).

I have a UNROM from an NFL cart and I am following Iceman's rewiring guide I found on here.

So I have the translated rom flashed to a 27C020 EPROM.

I lifted pins 1, 2, 24, 30, 31, and 32 on the PRG and
Pin 6 on the 161 and 9 and 10 on the 32.

Pin 1 is NC
Pin 2 to A16 (hole 22)
Pin 24 to GND
Pin 31 and 32 are tied to 5V (hole 28)
Pin 30 is tied to pin 8 of the 32 (3rd OR output)
Pin 17 ties D3 to pin 6 on the 161 (D3)
Pin 11 of the 161 ties Q3 to the 3rd OR input on the 32 (pin 10)
Pin 9 on the 32 is tied to pin 2.

Now that last step - IceMan said pin 9 can be tied to pin 2, 5, or 12 so they are all connected together.

Is that correct, that the 4 "B" OR inputs are all connected, because my meter says otherwise?

Any help would be much obliged.

SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

Re: UNROM to UOROM conversion

Post by SheriffTodd » Wed May 26, 2021 4:36 pm

I did a bit more digging and found the answer in this forum.
viewtopic.php?f=28&t=14829&start=15

Read through the conversation, it was very informative.
And as always, refer to chip pinouts and whatever your digital logic reference is to really understand what is going on here.

Law of the West (with translation patch)
Convert a UNROM to UOROM
Bridge the H for horizontal scrolling

PINS:
Bend up pin 1, 2, 24, 30, 31 and 32 of 27C020 EPROM
Bend up pin 6 of 74'161
Bend up pin 4 and pin 5 from 74'32

PRG ROM:
Pin 1 is not connected anywhere
Solder pin 2 to hole 22 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to 74'32 pin 6
Solder pin 31 to hole 28 (+5V)
Solder pin 32 to hole 28 (+5V)

74 Chips:
Connect pin 4 from 74'32 to pin 1 of the 74'32
Connect pin 11 of 74'161 to pin 5 of 74'32
Connect pin 6 of 74'161 to D3 of PRG ROM (DO NOT LIFT THIS PIN OF PRG ROM!)
Connect pin 6 of 74HC32 to pin 30 (A17) of PRG ROM (LIFT THIS PIN!)

OR

UOROM
Bridge the H for horizontal scrolling
27c020 EPROM
Bend up 1,2,24,30,32
Tie pin 32 to 31 (5v)
Pin 24 to gnd
Pin 30 to hole 1
Pin 2 to hole 24
(Probably optional:
Pin 1 to gnd
Hole 2 to hole 22)
Last edited by SheriffTodd on Fri May 28, 2021 2:10 pm, edited 1 time in total.

the_wizard_666
Posts: 62
Joined: Thu Feb 25, 2021 2:46 pm

Re: UNROM to UOROM conversion

Post by the_wizard_666 » Thu May 27, 2021 10:09 pm

Oddly enough, I'm working on one of these myself. Have you tested this? I can't seem to get it working, and I just want to make sure it's not the pinout you provided. Also, what donor did you use? Probably doesn't matter as they're all more or less the same configuration, but I want to rule out every possibility before shelving the project.

SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

Re: UNROM to UOROM conversion

Post by SheriffTodd » Fri May 28, 2021 1:05 pm

Yes, I did wire it up the other day and it did not work.
I am going to troubleshoot soon.
Yeah, I doubt the donor matters much as they all take a 128KB ROM, use a RAM chip and the counter and or gates.
I'll keep you posted, good luck!

SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

Re: UNROM to UOROM conversion

Post by SheriffTodd » Fri May 28, 2021 2:22 pm

Okay so what you wanna do is wire pin 4 of the or gates to pin 1, (or 8 or 11 or any +5V) which makes a ton more sense if you look at the back of the board.
This pic helped quite a bit as well.

http://forums.nesdev.com/viewtopic.php?p=83131#p83131

I wish I could remember my Digital Logic course from 20 years ago so I could explain better, but I believe it has something to do with the fact that pins 1, 8, and 11 are wired high, so if we connect pin 4, then all 4 OR gates are putting data out to the 4 high addresses, A14-A17...

...but I'm hoping I'm completely wrong about that so that someone smarter comments and helps elucidate.

Anyway, have fun talking your way out of gunfights!

the_wizard_666
Posts: 62
Joined: Thu Feb 25, 2021 2:46 pm

Re: UNROM to UOROM conversion

Post by the_wizard_666 » Sat May 29, 2021 10:54 am

Well, I think this game hates me :P I adjusted the wiring as you mentioned and it still won't boot. And the reason I'm using a donor in the first place is because I made it from scratch with a Muramasa board and it would crash at a specific point (when the enemy would get to the middle of the screen and start moving forward - it even did it during the attract mode), so I assumed it was incompatible with the board. Now it's refusing to boot up at all. It's not the patched ROM image, as it plays fine via emulator. It bugs me because it's probably gonna be something stupidly easy too :P

SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

Re: UNROM to UOROM conversion

Post by SheriffTodd » Sat May 29, 2021 4:50 pm

Oh man I'm sorry to hear that!
I love Muramasa's boards.
I use NFL Power Play for UNROMs mostly, but I wanna say Klashball is even cheaper, so I have a few of those coming.
Do you have pics of your board?

I'll try to post pics of mine.

SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

Re: UNROM to UOROM conversion

Post by SheriffTodd » Sat May 29, 2021 4:59 pm

Ok here are pics of my board. Please excuse the sloppiness and use of one color wire - it's just a time saver.
Feel free to ask questions, hope I can help.
Attachments
Resized_20210529_195511.jpeg
Resized_20210529_195442.jpeg

the_wizard_666
Posts: 62
Joined: Thu Feb 25, 2021 2:46 pm

Re: UNROM to UOROM conversion

Post by the_wizard_666 » Sun May 30, 2021 8:21 pm

Your wire paths look a bit different, but they are all connected to the same places on the board. The only difference I can spot is that I removed the mapper chips to bend the pins up, while it appears you may have cut them instead (hard to tell with the wires in the way though). We're even using the same variant board (my donor is Casino Kid, but the board is UNROM-9, same as yours). The only other difference is that while removing the 161, a pin broke off, so I used one of my replacement ones. Since it's a newer chip, it may have some compatibility issues. I may try swapping one off another donor cart (assuming I have one handy of course), but aside from that possibility, it appears the wiring is fine. If, however, you did NOT bend the pins up at all (even though your notes said to do so), I'll try connecting them back to their proper holes on the board with a touch of extra solder. But yeah, it looks like the wiring isn't the issue, so I'm kinda weirded out by it.

It is weird that it didn't work with the Muramasa board either though. That may point to an issue with the ROM itself rather than everything else. Although my luck with them has been pretty sporadic lately. I've have an ongoing save corruption issue with Destiny of an Emperor 2, a random crashing issue using the VRC board (Wai Wai World), and now this game. They work wonderfully for the most part, but it does make me hesitate a bit.

SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

Re: UNROM to UOROM conversion

Post by SheriffTodd » Sun May 30, 2021 9:10 pm

Well I know this game whether true UOROM or modded UNROM does not play on Retron consoles....totally freaks out.
Did you try the regular front loader?

No insult to your intelligence, but you have the H bridged, I assume?

Yes, I cut pins on the 74s, and funny you mention, it's hard to see from this angle but this particular 161 pin broke off too and I just managed by luck and the power of flux to not have to change it out.

BTW, my next project is something you've done before, the Metal Slader conversion from Laser Invasion, and I'd love to pick your brain...stay tuned for dumb questions ;)

the_wizard_666
Posts: 62
Joined: Thu Feb 25, 2021 2:46 pm

Re: UNROM to UOROM conversion

Post by the_wizard_666 » Mon May 31, 2021 12:07 am

Well, I haven't actually done MSG yet per se. Everything is set up, but I'm still waiting for chips to arrive because I didn't have one large enough for the PRG. The chips should arrive sometime soon, but you know how the postal service is...and being in Canada, it's even worse :P

The H is definitely bridged...I actually had to switch it because the V is bridged for Casino Kid. That said, it likely wouldn't stop it from running entirely.

So yeah, my guess is it's either an issue with the ROM chip, or a compatibility issue with the 161. I also haven't gone and done the once over with the multimeter to make sure everything is correctly connected properly, so there could be something else causing problems. I'll let you know if I figure it out.

EDIT: Well, looks like my 27C080s just arrived, so MSG is next up on the docket :)

SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

Re: UNROM to UOROM conversion

Post by SheriffTodd » Mon May 31, 2021 2:20 pm

Cool, I just attempted it and failed.
I'm not doing anything with the expansion sound, so I shouldn't have to populate any of the small components.
I assume I can leave all the CL pads bridged.
I did pull a trace on A16, but I hardwired to its destination.
At a loss at the moment.
I do have another Laser Invasion, so I may just move on to that one...my issue is the 27C040s are way more expensive than my source for 80s.

the_wizard_666
Posts: 62
Joined: Thu Feb 25, 2021 2:46 pm

Re: UNROM to UOROM conversion

Post by the_wizard_666 » Mon May 31, 2021 6:59 pm

I failed too, as per my post. The game is running perfectly fine, but there's no text displaying. I didn't change any bridges or anything, all I did was populate the extra bits for the sound.

I seem to be having some terrible luck with repros lately. Started off pretty well, but now it's kinda spotty :(

SheriffTodd
Posts: 10
Joined: Wed Apr 28, 2021 3:20 pm

Re: UNROM to UOROM conversion

Post by SheriffTodd » Sun Jun 06, 2021 9:07 pm

Hey, have you worked on Law of the West since we last chatted?
I made another today and the NES would not power on, so I double checked all the routine stuff and nothing.
Then I thought, no power, let's check power, so the pins 31 and 32 I have tied together to a cut component leg coming out of hole 28 for +5V. I checked it with my meter...checked against pin connectors 1 and 36, sure enough, a beed from both...so the glob of pins, leg, and solder were somehow touching a ground and +5...I pulled it up a bit and that fixed it.
Also, any success with Slader? I haven't looked at it since my failure.

the_wizard_666
Posts: 62
Joined: Thu Feb 25, 2021 2:46 pm

Re: UNROM to UOROM conversion

Post by the_wizard_666 » Thu Jun 10, 2021 6:45 pm

I haven't worked on much of anything to be honest. I'm trying to get caught up in school, so outside hobbies are at a standstill, at least so far as figuring things out. I may make another attempt on Law of the West now that my new parts have arrived, but MSG has been at a stand-still. I'm certain it's wired fine, and I can't figure out what's wrong with it. Like I said, everything is working except the text isn't displaying, and images that would normally appear in the text box are scrambled. It could be a mapper issue, or any number of other issues. I do have another Laser Invasion cart that I could convert as well, but the chips I need are expensive so I'm hesitant to try again without knowing what went wrong in the first place.

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