Nes Noob Repro Starter help

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silentadminz
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Nes Noob Repro Starter help

Post by silentadminz » Fri Jun 23, 2017 9:23 am

Hardware/nes specs:
So to start off I have a GQ-4x4, with the 16 Bit EPROM 40/42 pin ZIF adapter. (Not using the adapter atm) using USB only, no power adapter.
I ordered a bunch of Eproms, namely M27C512, AM27C010, M27C1001, and others. The ones listed are the ones I have in hand.
I have the CIC disabled(Pin4) on my NES front loader, and a Blinking light win installed. All other OEM hardware. Works with any original game I have.
Famirom for rom splitting to bin files.

Doing the work
I picked up a copy of Wheel of Fortune (Aorom) with a cracked case for cheap. I used http://bootgod.dyndns.org:7777 and found Jeopardy! (RevA) to be usable for a test run. Both of which only have a PRG to write. I used Famirom to spit out the .bin file of Jeopardy then imported the bin and used USBPrg (GQ-4x4 Eprom app) to burn an AM27C010 a 1m(128x8) chip. Did a blank check, wrote successful (I think). I'm thinking great, lets get the PRG off of the Wheel of Fortune and replace it with our freshly written AM27C010 with Jeopardy on it. Tested it and nothing, just a purple blinking screen. (Without wiring anything). Put the original Wheel of fortune PRG back on and test it, booted right up to the original donor game like a champ.

Confused am I doing something wrong
Puzzled I looked online and found docs online about wiring axrom boards Link here ( http://poorstudenthobbyist.blogspot.com ... ction.html )

Wiring More specifically the part where it mentions 32pin eprom wiring for axrom boards about a 1/4 the way down:
128KB PRG ROM:
Bend up pins 1, 2, 24, 30, and 31. Connect pin 1 to hole 30, Connect pin 2 to hole 24, Connect pin 24 to pin 16, Leave pin 30 and pin 31 disconnected
256KB PRG ROM:
Bend up pins 1, 2, 24, 30, and 31. Connect pin 1 to hole 30, Connect pin 2 to hole 24, Connect pin 24 to pin 16, Connect pin 30 to hole 1, Leave pin 31 disconnected

Verified continuity to wires/pins/vias - I tried both of these wiring methods with no results.
Did I not wire it correctly, does it need wiring, or did I write the chip wrong. I left everything default when burning the chip and importing the bin file. Even did a blank check after I wrote it and it did indeed have data on it. Can provide pics if needed of my hack job of wiring or anything else. Someone point me in the right direction? :shock:

I'm trying to burn "Jeopardy! (USA) (Rev A)".

lidnariq
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Re: Nes Noob Repro Starter help

Post by lidnariq » Fri Jun 23, 2017 10:29 am

Some AxROM games specifically require not having bus conflicts. Unfortunately, which is which is underdocumented.

Games originally shipped on AMROM boards explicitly do have bus conflicts; games originally shipped on ANROM don't; games on AOROM might or might not.

If this is what's wrong—and Jeopardy! was originally shipped on ANROM—then you'll need to add an inverter to the cart to remove bus conflicts. There's a wide variety of parts that you could use—e.g. 74x00, 74x02, 74x04. Invert R/W—it's already present connected to the 74xx161—and connect the generated W/R to your PRG ROM's /OE pin.


I'm uncertain whether this thread should be moved to the Reproduction forum. We haven't exactly made it clear whether "Newbie help center" means "for everything but reproductions"...

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silentadminz
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Re: Nes Noob Repro Starter help

Post by silentadminz » Fri Jun 23, 2017 11:18 am

First off sorry about posting in the potentially wrong area. I'm new around here and didn't see the Reproduction Forums. This post can be moved if required.
This being my first repro, probably not my greatest choice as a starter cart I can see lol. But I'll see if I can follow you here using the links your provided.

I have 2 options:
Either use 74x00, 74x02, or 74x04 part in place of the 74x161 chip
OR
Find the CPU R/W Pin (pin 14 on the US cart I think) and trace it to the 74x161 pin out, connect its traced pin to the /OE (pin 24) on my AM7C010?

&Keep the other wiring intact as well(128KB PRG ROM: Bend up pins 1, 2, 24, 30, and 31. Connect pin 1 to hole 30, Connect pin 2 to hole 24, Connect pin 24 to pin 16, Leave pin 30 and pin 31 disconnected)

At least this is how I interpret it. I'm not super savy with electronics persay, but I can be directed and execute accordingly.

Appreciate the help/reply btw.

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Re: Nes Noob Repro Starter help

Post by lidnariq » Fri Jun 23, 2017 11:35 am

silentadminz wrote:Either use 74x00, 74x02, or 74x04 part in place of the 74x161 chip
OR
Find the CPU R/W Pin (pin 14 on the US cart I think) and trace it to the 74x161 pin out, connect its traced pin to the /OE (pin 24) on my AM7C010?
No, sorry I was unclear.

You need both the 74x161 and an inverter.

If you do decide to add an inverter, you need to take R/W (pin 9 on the 74x161), connect that to one of the inputs on the 74x00, 74x02, or 74x04 to generate a signal that is low when R/W is high, and connect the output of that inverter to your ROM's /OE pin.

Alternatively, you could temporarily give up on making a Jeopardy! copy and instead pick a game that originally shipped on AMROM—those don't need the ability to prevent bus conflicts.

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silentadminz
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Re: Nes Noob Repro Starter help

Post by silentadminz » Fri Jun 23, 2017 12:18 pm

No, sorry I was unclear.

You need both the 74x161 and an inverter.

If you do decide to add an inverter, you need to take R/W (pin 9 on the 74x161), connect that to one of the inputs on the 74x00, 74x02, or 74x04 to generate a signal that is low when R/W is high, and connect the output of that inverter to your ROM's /OE pin.

Alternatively, you could temporarily give up on making a Jeopardy! copy and instead pick a game that originally shipped on AMROM—those don't need the ability to prevent bus conflicts.
Ahh, I see. perhaps a bit out of my abilities at the moment. Although I'm sure I could manage it. It sounds like AMROM boards are also compatible from what you said. I'll look into that.
Jeopardy was just a test of course. I mean let's be honest who wants to play Jeopardy on the NES :lol:
Ultimately I wanted to turn it into Battletoads, but was waiting on the 2m Eproms I have on order.

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poorstudenthobbyist
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Re: Nes Noob Repro Starter help

Post by poorstudenthobbyist » Sun Sep 27, 2020 8:34 pm

Is there some newer documentation about which AOROM games have issues with having bus conflicts, besides Wheel of Fortune and Double Dare?
Are there specific games that require bus conflicts to operate correctly? (If not, one can just use ANROM games for AOROM and AMROM, correct?)
Check out my website for NES, SNES, and Genesis tutorials here. And visit my store for some custom tools and boards for making games here.

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Re: Nes Noob Repro Starter help

Post by lidnariq » Sun Sep 27, 2020 8:56 pm

I know of no AxROM games that require bus conflicts; the emulator specificity is instead about keeping people from making ROM hacks or homebrew that rely on the absence of bus conflicts.

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poorstudenthobbyist
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Re: Nes Noob Repro Starter help

Post by poorstudenthobbyist » Tue Oct 06, 2020 7:23 am

For ANROM, couldn't you just make a simple logic inverter for the R/W signal with an NPN, and wire it up to the previously-permanently-grounded /OE pin? That seems way easier than using an entire 16-pin logic chip to invert one signal. Why would Nintendo use that instead of just a transistor and two resistors? Cause they had a bunch of '02s lying around?

I tried that with AOROM game that originally utilized the extra positive-logic OE pin on pin 31 and it worked fine.
Check out my website for NES, SNES, and Genesis tutorials here. And visit my store for some custom tools and boards for making games here.

You can also follow me on Twitter for infrequent updates and bad jokes!

lidnariq
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Re: Nes Noob Repro Starter help

Post by lidnariq » Tue Oct 06, 2020 11:26 am

poorstudenthobbyist wrote:
Tue Oct 06, 2020 7:23 am
For ANROM, couldn't you just make a simple logic inverter for the R/W signal with an NPN, and wire it up to the previously-permanently-grounded /OE pin? That seems way easier than using an entire 16-pin logic chip to invert one signal. Why would Nintendo use that instead of just a transistor and two resistors? Cause they had a bunch of '02s lying around?
My best guess, without any good evidence, is resistor-transistor logic had some kind of compatibility problems. Maybe it was with the assembly method (can you wave solder a TO-92?), or maybe it was timing problems.

Nintendo did have a few boards that used RTL: RTROM, STROM, SROM, and SL1ROM have it. But almost everything else used a whole 74'32 or sometimes something more complicated.

FrankWDoom
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Re: Nes Noob Repro Starter help

Post by FrankWDoom » Tue Oct 06, 2020 1:05 pm

If you're just starting and trying to get a handle on what you're doing, maybe pick a more straight forward application like simple nrom or cnrom. There are caveats with basically everything else that can be dealt with when you have a grasp on what you're doing.

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poorstudenthobbyist
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Re: Nes Noob Repro Starter help

Post by poorstudenthobbyist » Tue Oct 06, 2020 8:49 pm

lidnariq wrote:
Tue Oct 06, 2020 11:26 am
My best guess, without any good evidence, is resistor-transistor logic had some kind of compatibility problems. Maybe it was with the assembly method (can you wave solder a TO-92?), or maybe it was timing problems.
Wave soldering TO-92's doesn't pose any problems, unless wave solder technology was very far behind back in the 80s haha. But FWIW, here's some scope captures. Base resistor was 10k, collector resistor was 1k. Yellow is Vce, blue is CPU_R/W.
The scope trace that has less rounded Vce is with a 1k base resistor, though, I'm not sure if I should be driving the transistor at ~0.5mA from the R/W signal. The negative spikes bug me.

I don't know how much the rounding matters. The game has been running for a few hours now without any issues. I also tried one with a collector resistance of 10k as well, which produced even more rounded signals that sometimes didn't even rise to 3.5V, and the game still worked fine. But maybe this explains why Nintendo stuck to CMOS chips. I just would much rather use 3 cents worth of combined parts instead of one 50 cent part.
FrankWDoom wrote:If you're just starting and trying to get a handle on what you're doing, maybe pick a more straight forward application like simple nrom or cnrom. There are caveats with basically everything else that can be dealt with when you have a grasp on what you're doing.
I am not OP, I'm just hijacking a thread that mentions AxROM games that I had a question on :D
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Check out my website for NES, SNES, and Genesis tutorials here. And visit my store for some custom tools and boards for making games here.

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Re: Nes Noob Repro Starter help

Post by lidnariq » Tue Oct 06, 2020 9:03 pm

poorstudenthobbyist wrote:
Tue Oct 06, 2020 8:49 pm
I just would much rather use 3 cents worth of combined parts instead of one 50 cent part.
Well, nowadays you can get rather inexpensive 74'1g04s too. Those smaller packages weren't an option during the NES's commercial life, however.

Maybe NoA really just wanted to use parts where if there was a problem they could blame someone else. Doing some bespoke RTL means you have to own the design, both good and bad.

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poorstudenthobbyist
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Re: Nes Noob Repro Starter help

Post by poorstudenthobbyist » Tue Oct 06, 2020 9:15 pm

lidnariq wrote:
Tue Oct 06, 2020 9:03 pm
poorstudenthobbyist wrote:
Tue Oct 06, 2020 8:49 pm
I just would much rather use 3 cents worth of combined parts instead of one 50 cent part.
Well, nowadays you can get rather inexpensive 74'1g04s too. Those smaller packages weren't an option during the NES's commercial life, however.

Maybe NoA really just wanted to use parts where if there was a problem they could blame someone else. Doing some bespoke RTL means you have to own the design, both good and bad.
Hm, I hadn't thought of those parts. I'll look into those. It's just annoying cause I have my parts cabinet all nicely laid out and full - I already had 1k, 10k, and NPNs. Now I have to combine some parts drawers to make room!
Check out my website for NES, SNES, and Genesis tutorials here. And visit my store for some custom tools and boards for making games here.

You can also follow me on Twitter for infrequent updates and bad jokes!

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