FPGA Based Videogame System

[Andromeda Stardust]

Re: the cart connectors. The carts are quite slow devices, so the plan was to run the bus on the small connector at 50 or 100MHz, and funnel the data through it that way. I got lots of time (in nanoseconds) to get addresses and control signals ready at that speed, relative to the speed of the game system bus. I expected it to be good enough for NES, 2600, etc and most likely SNES but definitely not good enough for neogeo since those carts are obnoxious. Each adapter would have some kind of CPLD/small FPGA in it to do the demultiplexing and remultiplexing to poke the data through the interface.

 

I definitely plan on running the game on the carts directly, and I do not want to merely dump/run them like a retron 5.

 

Like most things I do, the physical parts are going to be the difficult ones probably for this; specifically what kind of enclosure to use. I will most likely be using laser cut acrylic for the cart adapters if I do them simply due to the low volume. Injection molding doesn't make sense unless there's thousands of units made. I suspect the number of people who want an Arcadia 2001 cart adapter can be counted on one hand so it's not viable to do it any other way.

 

Originally I was thinking of making an obnoxious cart board with say 16+ cartridge ports, one for each system, and then have buttons to select one of the ports to use but I think that'd be really silly and wouldn't be terribly practical. Again, just about anything is possible, but I have to whittle it down to what's practical.

Maybe you could do cart adapters in "sets" ie An Atari model with 3 slots for 2600/7800, 5200, and 8-bit/XEGS. A Nintendo cart adapter with slots for FC, NES, SNES, and Game Boy. A Sega cart adapter with SMS, Genesis, and Game Gear. Do a combined cart adapter for Intellivision + Colecovision since many gamers collect for both. Lump the more obscure stuff together. That way you don't need dozens of SKUs to cover every system. Each adapter is slightly more expensive, but it would be cheaper to buy adapters for multiple systems.

 

Laser cut acrylic seems very neat. The PCB mount holes could be the same and all you need to modify is the cart slot cutouts on each design. One caveat is the acrylic add-ons would look awkward with an injection molded console body. Might as well make them match!

[Andromeda Stardust]

A device with such a high number of ports would be too bulky, and most of the cartridge ports would remain unused. But something to consider would be triple-port adaptors. For example:

 

1) Atari 2600 + Atari 5200 + Atari 7800

2) ColecoVision + Intellivision + Vectrex

3) Sega Master System + Game Gear + Genesis

4) NES + Game Boy / Game Boy Color + Super-NES

 

Dang it, I posted before I read your post. Great minds think alike!

[EvilDragon17]

Nice progress

 

I especially like the prototype version with hundreds of cables in your video

[Schizophretard]

I think I would prefer something like a universal cartridge slot right on top of it with cartridge adapters that fit snug into it that get released with an SNES like eject button. Multiple small adapters with only one universal slot would be preferable to multiple big adapters with a slot for each one.

[Guspaz]

I had suspected that some sort of multiplexing would happen, but in reference to the question about the 72-pin connector, it's worth pointing out that a 4x PCIe slot has 64 pins, and the 10 expansion pins on the 72-pin connector aren't needed for typical use, and ground is duplicated. So you only really need 61 pins on the connector. There may be other pins that the NES doesn't typically use (the Famicom only has 60, and a bunch of those are duplicated), but I'm not familiar enough with NES architecture.

[rgb32e]

Since UHDTVs are becoming more and more common, I believe you should provide 2160p60 output (4:4:4) to "future proof" the video output. TV manufacturers are phasing out 1080p in favor of 2160p. Unfortunately most UHDTVs do not do a very good job of upscaling 1080p graphics to 2160p. It's been incrementally improving each year, but in most cases 1080p60 is chroma sub-sampled when upscaled, resulting in ringing on both horizontal and vertical edges.

 

The only exception thus far has been from Panasonic, as they provide a 1080p by 4 pixel mode that does the "correct" scaling from 1080p to 2160p. Unfortunately the input lag on these sets are not very gaming friendly (high). Hence, I believe it would be worthwhile to include a 2160p capable FPGA to handle the upscaling.

Edited October 22, 2015 by rgb32e

[leods]

You guys actually thinking of buying a 4k Display in the near future? I'd say that to Play classic games it's not really worth it. lol

[Guspaz]

4K TVs and monitors today are cheap (they start at $500 on BestBuy, $400 at MonoPrice) and relatively common (BestBuy has 107 of them). We're basically in the middle of the transition to 4K, and as such a device with a maximum output at 1080p will work fine today but be increasingly obsolete going forward.

 

That's not to say that 1080p signals don't work fine on 4K TVs, but it's better that the upscaling be done on the console with nearest neighbour rather than let the TV upscale it.

 

The problem might be that the scaling is being done on the MAX 10, which is on the mainboard, not the AV daughterboard, so if it couldn't handle the scaling, it'd be a problem.

 

Possible workaround: a 4K AV module with its own scaler. When the 4K AV module is installed, the MAX 10 skips the scaling and just sends the native display resolution to the 4K board, and the 4K board handles the scaling itself. That way, if the MAX 10 isn't fast enough to do 4K HDMI output by itself, the overall system cost would be unchanged, and people who want 4K could buy the 4K AV module, which would cost more than the normal HDMI module.

[MarkVI]

I think that even though many people today think 4k is overkill, I assure you that in 5 years everybody will want all their devices output to 4k with whatever standard there is, regardless of practicality.

 

I think the way Kevtris has designed the Zimba 3000 is very intelligent, because it does allow for a high degree of modularity. FPGAs are reprogrammable by definition (including the MAX 10), so I'm sure it'd be possible to build a 4k AV module as suggested above that could bypass the MAX fpga for the upscaling and do it directly on the add-on board.

 

Anyway, I'm excited to see how this project goes. And maybe if it's a success we can hope for a Zimba 4000 with ps3 support (maybe).

[Osgeld]

4k is so yesterday you can get 8k for cheap nowdays and it would be intolerable to view 16x32 pixel Mario in anything else but 8k!

 

It's funny emulator people are going out of their way so simulate the perfect crt meanwhile console players think their lives would be ruined if combat wasn't in effin 98k umuahd (ultra mega unreal awesome high def)

Edited October 23, 2015 by Osgeld

[Andromeda Stardust]

240p 15kHz is the gold standard for classic arcade and console games.

 

Seriously, 240p is scaled to 1080p and upscaled to 4k. Who the hell cares? You get sharp, square pixels either way. The RetroUSB AVS and Retron5 do 720p. It looks fine scaled to 1080, which btw is not an integer ratio. 2x Integer scaling from 1080p to 2160p will result in even cleaner sharper picture with less artifacts. For 720p sources, it's a perfect 3x integer ratio as well, or 9x total upscale from 240p.

 

However, for gaming purposes, I would not recommend anything higher than 1080p native resolution. Preferably a 1080p PC monitor without all those fancy filters would be ideal for HD gaming. 4k sets would be nice for overlaying a CRT mask however, along with post-processing effects like phosphor trails, spherical CRT distortion, composite/RF bleed, etc which may not look right at 1080p. Especially a CRT mask at 1080p may create moire patterns.

[+AtariNerd]

Oh, I don't know - I'd like to see someone try to simulate a Vector display on a 4K or 8K OLED panel.

[Andromeda Stardust]

Oh, I don't know - I'd like to see someone try to simulate a Vector display on a 4K or 8K OLED panel.

OLED + Games = Screen burn...

[roland p]

OLED + Games = Screen burn...

So back to crt then, and a Zimba 3000 with native output... Edited October 23, 2015 by roland p

[Schizophretard]

I think he should save 4K for the Zimba 4000 so that he can call it the Z4K with an extra meaning to that.

[+iesposta]

Oh, I don't know - I'd like to see someone try to simulate a Vector display on a 4K or 8K OLED panel.

Vectors on the iPad Retina display, although far from an arcade monitor due to not having any simulated effects, begins to show awesomness...

[rgb32e]

4K TVs and monitors today are cheap (they start at $500 on BestBuy, $400 at MonoPrice) and relatively common (BestBuy has 107 of them). We're basically in the middle of the transition to 4K, and as such a device with a maximum output at 1080p will work fine today but be increasingly obsolete going forward.

 

That's not to say that 1080p signals don't work fine on 4K TVs, but it's better that the upscaling be done on the console with nearest neighbour rather than let the TV upscale it.

 

I completely agree! Glad to see there are non-hidebound posters on this forum!

[Guspaz]

Don't get me wrong, I'm using a Sony PVM as my primary display... But they're hard to find, they're fussy, and it's not reasonable to expect people to go through that kind of trouble to enjoy older games. As such, the more important thing is making old games run well on current (and future) displays. Those of us with PVMs are either going to use the original systems, or we'll just be happy with a simple RGB output module (the modular output aspect of the Zimba 3000 is a fantastic idea). So our use case is easily taken care of.

 

Latency is also a concern, because televisions often have lower (sometimes much lower) latency when displaying at their native resolution than when they're upscaling. I've done no testing on the matter, but I would think this would apply even more to 4K TVs upscaling from 720p or 1080p.

[+kevtris]

Unfortunately, more than 1080p is pretty difficult with an FPGA. That's almost a 150MHz pixel rate, so doing anything higher is pretty much out of the question. I don't think that transmitter chips exist for 4K yet even. You almost need custom ASIC hardware to drive 4K video these days. I dunno even if one of the expensive FPGA's SERDES could run fast enough for 4K stuff.

[Andromeda Stardust]

Latency is also a concern, because televisions often have lower (sometimes much lower) latency when displaying at their native resolution than when they're upscaling. I've done no testing on the matter, but I would think this would apply even more to 4K TVs upscaling from 720p or 1080p.

Which is why I highly recommend using displays with native 1920x1080p resolution. PC monitors are perfect for this. No laggy filters or processing, or unnecessary TV tuners or ADC converters. They are generally smaller than HDTVs though. Also analog output on the game console is useful for those displays that do not have a phono jack to bypass audio to an external sound system, or anything with a DVI port.

Edited October 24, 2015 by stardust4ever

[Guspaz]

Unfortunately, more than 1080p is pretty difficult with an FPGA. That's almost a 150MHz pixel rate, so doing anything higher is pretty much out of the question. I don't think that transmitter chips exist for 4K yet even. You almost need custom ASIC hardware to drive 4K video these days. I dunno even if one of the expensive FPGA's SERDES could run fast enough for 4K stuff.

 

Unfortunate. But if you leave the option open to having a secondary scaler on the AV board, then if 4K scaling becomes a possibility in the future (perhaps a low-latency dedicated scaler chip), then it could be a potential future upgrade some day.

[leods]

I don't really get this whole 1080p getting obsolete. For what? I still watch mostly new DVDs on a 720p TV. New Generation consoles aren't even hitting 1080p 30fps. 500 bucks sounds cheap, but a 1080p costs what? 300$ if that much?

 

Companies want you to believe stuff is obsolete. Well, I don't beleve them...

 

Of course in 10 years from now things will be different. But by then I'll buy the Zimba 5000.

 

we're talking about Hardware that costs 200-250 Dollars. You can't expect it to be "future proof" for the next many years. If top end Computers can't really Play games at 4k why would we worry about that`?

 

I don't know. To me sounds like People like upgrading just to have more Problems. Me I like having old obsolete stuff. I pay a third of the Price and have a way better experience because I can buy Mainstream things that are very easy to operate and solve any Problems.

 

As if 4k will make a trashy Hollywood movie any better...

[Schizophretard]

4K TVs and monitors today are cheap (they start at $500 on BestBuy, $400 at MonoPrice) and relatively common (BestBuy has 107 of them). We're basically in the middle of the transition to 4K, and as such a device with a maximum output at 1080p will work fine today but be increasingly obsolete going forward.

This transition has started and yet 720p TVs are still for sale and not obsolete yet. Therefore, I suspect that by the time 4K has been adopted to the extent that 1080p has it will be 720p TVs that get fazed out with the 1080p TVs taking their spot. So, 1080p TVs will likely stay an option for quite awhile. Also, if we just waited patiently to upgrade by only doing it when our current TVs completely break down instead of being early adopters that upgrade ASAP then by the time we upgrade to 4K the TVs we would buy would make the current 4K TVs you are referring to obsolete which could mean getting better than what is the top of the line today for cheap, better scaling technology, less video lag,etc.

[+phoenixdownita]

I say don't worry about 4K for now, already 1080p is good.

I hope I can set the Z-3000 to 720p, my main TV is a 720p and I don't intend to buy a new one anytime soon.

I understand that 720p is an odd number (240 x 3) but even 1080p is not exactly a multiple of anything neither 240 nor 288.

 

Anyway please do let us know if 720p is going to be supported.

[Bill Loguidice]

The 4K thing is really a non-issue in my opinion. Unless it's relatively trivial and inexpensive to make this 4K capable now, I think it's best just to make it 1080p native and leave it at that. There are still tons of devices being produced that max out at 1080p, so it will continue to be a supported resolution for a long, long time to come, even when 8K TVs become standard. By the time it would be specifically desirable to output native 4K, it would likely be time for successor hardware anyway.

 

By the way, anecdotally, we have a relatively inexpensive 4K TV in our bedroom, and it seems to do fine upscaling (video and game) 1080p content. As these TVs get better, I'm sure that will only improve.