The big problem I see is no sustainability. This Super 8 NES only works if there are donor systems. You can't always guarantee a steady stream of donors, but brand new chips can always be re-produced. Developing an RGB PPU replacement should be top priority. The supply of PlayChoice donor boards is much, MUCH smaller than NES systems.

I have 16 NES's in my closet, and 3 parts systems. I'd be willing to transfer my parts over to a better/easier layed out system for a more reliable test/dev machine. Although my original NES's honestly work just fine too. Although I think if the price point is low enough, it'd be a good thing to have for people who want better video and easier modding.

I disagree with the notion that we can't build a 100% accurate nes.
Fpga's can in theory replicate the system 100%. The only real analog parts on the system are the audio and the video path. Both are well known and can be recreated at our whim.

We also have decaps of both the 2a03 and 2c02. They have yet to be properly analysed, but if they were we could deduce the system workings 100% correctly.

It'd be alot of work, but Kevin Horton basically already did it with the info we have right now. Probably making it 99.99% accurate. (and that's because we can't verify it against the chip decap) It even does composite video the same way the NES would've. (and rgb and dvi for those interested in that). For all intents and purposes even if it differed 0.01% almost nobody but devs LOOKING for that particular bug could tell the difference.

edit: should've mentioned this would be done on an fpga. Which is NOT the same as software based "emulation".

edit2: also it is a little idealized in that I assume the person writing the verilog doesn't mess ANYTHING up.

Another thing to consider, is that a much smaller and cheaper FPGA could be used as a substitute for the CPU and PPU, since the RAM chips are discrete components. It would almost be easier to just convert a toaster NES into a top loader by gutting the loading tray, cutting a rectangular hole on top of the console, soldering 72 wires from the PBC to a strait 72 pin connector, and mounting the connector into the hole on top of the NES. Oh, and cut pin 4 of the lockout chip. Boom, and you've got a converted, region-free top-loading NES with AV output. Then you could add a 60-pin connector for Famicom carts and wire up a 15-pin plug to the original NES expansion port, so you could use all existing Famicom and NES accessories.

Basically, you could mod the heck out of an existing NES to make it more reliable, rather than spending tons of $$$ creating a homebrew PCB from all new hardware, and still end up sacrificing a perfectly good NES for the CPU/PPU in the process.

Euhm typically the ram isn't ON the fpga but external. (at least every board i've looked at)
So you can't use a "Much smaller fpga". You'd save some space on the mappers I guess, but it's stil not the bulk of the space used.

Also you'd need logic level converters to convert the fpga 3.3v to 5v for the cart slot, and it'd take alot of them. So that drives up the price alot.

I do have the boards on order for v1.0 of the NES Super 8 finally. Normal manufacturing time is 14 business days.
Not much else to do but wait. I have the parts already and can't wait to finally assemble one.

I've checked the connections multiple times and worked so long on this project already, I just needed an actual board to test and see how close I am to my design goals.

It's my first time doing a circuit this complex, so I'm a little nervous.

Good luck, keep us posted.  How do the control ports, power buttons, etc....all connect?  Manual soldering or same connectors as original parts?  Just curious as that is some useful info lol.

Can't wait to see!

I received my prototype boards yesterday and finally got to assemble a NES Super 8. I used the CPU and PPU I removed from my parts NES system.
I used the original controller ports soldered to header pins for testing. Future versions will have the NES controller ports I got from parallax.

I am happy to say, everything works. The composite picture appeared to be quite good, and the sound amp I used worked great. I tested it on a portable DVD player.

This weekend I will test the system on a couple different TVs and see if any tweaks are needed in the video amp. I may try a couple different circuits to find the best one. I expect to have a noticeable improvement over composite video from an original NES, but nothing major.

I will also test different games, the Powerpak, and accessories like the Zapper to make sure they work, although I see no reason they wouldn't.

Then of course I will test the RGB PPU and check games for any jailbars or graphical glitches. I'll test this PPU using a PSOne screen and my Jrok component video encoder.

Finally, I'm going to cut the AG-85 case and fit the components inside. The PCB is a perfect fit, it just requires the 2 front corners be cut back slightly. It will be a busy weekend.

There were only two minor issues with v1.0.

My component footprint for the PTH08080W voltage regulator was off so it doesn't fit. Doh! I'll just buy some adjustable regulators from ebay as they are cheap and small. A 7805 would work too, but it gets hot and requires a heatsink. I'd rather not butcher the case with lots of vent holes.

There was an area of the ground plane that was a little narrow leading to one of the memory chips and the 74HC373. I just added a jumper to ensure they had adequate grounding.

I will post some screenshots soon.

Wow, looks cool so far man, cant wait til the final product!

this is looking good

I'm officially 300% in for one! Damned board is small as a cart, and the polycase makes it look like a Master System 2! http://images.mylot.com/userImage...

Love the project. I've been thinking about a project like this ever since I was in the portables community on benheck.com. I don't really care as much about portables now, but this would be a great testing station for the misc NES components I have kicking around. I won't have to sacrifice a working NES and put sockets on it.

Nice. Would you be willing to sell some boards sans CPU and PPU?

This sounds legit! Can't wait to see pictures!

Drool! This is amazing so answer me this would one be able to just simply put in a RGB PPU? Like this one http://www.nintendoage.com/forum/... I am not too tech savy when it comes to these components.

Very cool! Lookin' good

I've been too busy lately working overtime and helping parents move to get much done on the project.

The Super 8 project still needs a fair amount of work done. I don't think it will be totally ready for some time.

I did some more testing, and have a much better idea what works and what needs some tweaking.

All the games I tested (about 20) work, as well as the Powerpak. There didn't seem to be any compatibility issues.

The sound circuit is perfect the way it is. The headphone amp I used works much better than using a hex inverter as an amplifier like the original NES. The potentieometers let you mix the sound any way you want.

Controls work fine without the 330p caps or the diode arrays. I might add them and see if that effects anything.

I did notice some issues I need to work on.

The composite video looked good on the portable DVD screen, but was too dark on some LCD TVs.
Going to try a different (simpler) amp circuit.

The colors seemed to be off slightly.
This may be a problem with the clock circuit. I may need to change some capacitors to get the right value. I'm guessing TC1 fine tunes the clock timing and effects the composite video palette?

I haven't tested the RGB PPU yet. I am going to improve the composite video output first. I want the Super 8 to work well with either PPU.

I attached the schematics of the video and clock circuits I used.
The video amp has changes I am going to make in black.
The clock circuit has the current circuit I use in black. I had to change the original NES clock circuit slightly because I couldn't find 51p capacitors or a exact match for TC1.

I posted a [crappy] video of the Super 8 being tested at

.
While doing a search for my video, I found out there was a Chinese accessory made for the SNES called the Super 8 that lets you play NES games. Oh well I'm not changing the name at this point. 

Just tested Super Mario Brothers 3 today and found it didn't work.
It plays fine on the Powerpak, but the original game won't boot.
The NES Super 8 needs 100% compatibility, dammit
UPDATE: works, just had dirty connector


The ram I used is 10x faster than the original NES memory and that on the SMB3 cart, could that be a problem?
I'm wondering if I could configure the Super 8's onboard memory to 4k and disable any extra cart memory, but I'm not sure if that would make some games incompatible that are currently working.
UPDATE: no, definately not adding more memory

I have also started work on v1.1 of the Super 8, but I want everything working correctly on v1.0 before I have v1.1 manufactured.

I think permanently enabling 4k wram causes some problems in some games. (I think some of them use the mirrored space).

Smb3 not working sounds like it might be something with the irq line?

What does SMB3 look like? Is A12 working like it's supposed to?

And no, DO NOT include any more memory or change the default NES layout. Some games rely on mirrors and will break if anything is changed. Extra ram at 6000-7fff? Broken for copy protection. Extra 2KB main RAM? Broken because of gams that write to mirrors. Extra 2KB VRAM? No mirroring, games will write to bad mirrors. Don't do that.

I concur with 3Gen. The NES, like most older systems, is very particular in regards to how it uses its resources. Any deviation will likely result in some sort of failure or otherwise undesirable behavior.

Thanks for the info. I wasn't sure exactly how mirroring works.

When I try to boot Super Mario 3, all I get is a solid color "puke green" screen.
Oddly, the system does the same thing when no game is inserted.
I re-checked the irq and A12 lines, they go to the correct pins (when compared to the NES front loader.)
I don't know what could be causing he problem, the connections are pretty much identical to the front loader NES.

What are some NES games that have additional CPU or PPU memory on the cartridge? I would like to test these games as well.

I am considering eliminating the need for U9 on the board if possible, it is the hex inverter. I am currently only using one of the inverters. The NES front loader used it for the lockout chip, system reset, and audio, which I don't need. On the Famicom, U7 or U8 is used instead so there is no U9 on these systems. Only problem is getting the cartridge slot pins up to U7 or U8, there isn't much room left.

I have freed up some space on the PCB, I could use it to mount one controller port, but both won't fit on-board. I could maybe move the voltage regulator over to this area as well.

http://bootgod.dyndns.org:7777/

Thank you for your work