VGA16 FPGA based Scan-Doubler for the Neo Geo

[beharius]

VGA16 Scan-Doubler for the NEO GEO
We are releasing an FPGA based line-doubler for the Neo Geo MVS arcade boards which is installed internally. It's outputting a progressive VGA signal (640X480) by tapping the digital video signals from the board. There is no loss in video quality and no lags since a frame buffer is not used. Its FPGA line doubles the signal on the fly (264 lines to 528) then handled by a DAC similar to the original Neo Geo design which converts it to analog video. Hence it's refresh rate frequency is off spec(59.1856Hz) instead of the required 59.94Hz for the 640x480 video timing format, more tolerant VGA output was preferred instead of the strict HDMI standard for compatibility issues.
The installation is very simple unlike the other internal digital video mods out there. There are only 20 wires to be soldered. It uses 5 bits per each RGB colors(5x3), a sync signal, a CLK signal taken from the 68000 CPU(or mainboard), 2 grounds and a 5V. So 20 wires in total. These are all next to the 74ls273 latches, on the resistors.
This mod also offers Scanlines and Pixel Blending features. These can be set by the jumpers on the board or a dip-switch to be installed on the enclosure. You can set its density by setting jumpers as 00 none,01 low,10 medium, 11 high. Pixel blending give a nice CRT experience for the user.



MV-1F installation


MV-1C installation


https://www.youtube.com/watch?v=2mA1QCSoqO4



This project will be offered as a DIY kit including all the wires, please note that final boards will have an 20pin IDC socket, so only wires for the MVS mainboard need to be soldered. We will also release a limited edition, premium Consolized MVS to commemorate our 7th anniversary. This will feature a car painted high quality metal enclosure including VGA(480p) and Scart(480i) outputs. An original, upgradable UniBios. Each bios can be individualized for your needs(name, serial etc.) too.


Price will be $100 including shipping. Pre-ordering TBA soon.
It's developed by our new FPGA coder, Eins, a very experienced designer in this field. So more to come soon...


BEHARBROS
http://www.beharbros.com

[mikejmoffitt]

Neat! I got very tired of putting together and shipping the NeoVGA kits, so I can direct some people to you who are looking for something like this.

This is a minor nitpick, but the original 264 line signal isn't interlaced.

I noticed you are taking the pixel bus signals from the outputs of the '273s. I recommend taking it from the inputs to these ICs instead, which will matter more for the DAK and SHAD signals than anything (are you considering these ones as well?) The blanking input to the '273s is useful to take advantage of as well.

If you move to an active DAC, you could consider integrating an RGB --> YUV conversion on the FPGA, for perfect component output.

Which FPGA are you using? Is it an EP2C5T144 ?

[beharius]

Thanks for your support. Actually this was designed in 2016 right after yours for personal usage so it's not released until now.
Those signals are unused in this project. We will consider your advice, tapping the signals from the resistors is easier for installation though.
Yes, it uses that FPGA (Cyclone II).

[mikejmoffitt]

Thanks for your support. Actually this was designed in 2016 right after yours for personal usage so it's not released until now.
Those signals are unused in this project. We will consider your advice, tapping the signals from the resistors is easier for installation though.
Yes, it uses that FPGA (Cyclone II).

The pins I am suggesting to tap are just one off from that of the '273's output pins; the installation effort should be the same.
If you aren't using DAK or SHAD, you will find some subtle errors in certain scenes.

[beharius]

OK, we will check it again. Thanks.

[andy251203]

Any updates on this? Interested in preordering when it's available.

[beharius]

We just received the boards. After programming and testing, we will start to take orders.

[andy251203]

Will these work on 2-slot, 4-slot and 6-slot boards?

[beharius]

Afaik all boards have the same video output circuit/DAC, so it should.

[mikejmoffitt]

The later chipsets (like NEO-GRZ) have slightly different sync timings and blanking signals.

[beharius]

We haven't tested it on multi slots since it's impossible now to source them here. I haven't seen anything wrong with others although the firmware can be upgraded easily in case of any issues.

[mikejmoffitt]

The difference between MV-1C and earlier units is enough for it, the multi slots all conform to the old behavior.

[Hoagtech]

Im very excited for this beharius. This will be a game changer.

I always wanted a Neo geo I could bring to my brothers house that didn't consist of a cardboard box full of cords

Great work guys.

[beharius]

Finally we completed this project. It's completely redesigned and we added some new features after taking into account dear Mikejmoffitt's considerations. Both DAK and SHAD signals are processed now.
In addition to the VGA output, YPbPr output is also offered. It's selected with a dipswitch and both can't be used at once. We also separated and moved the Clock signal which can be soldered with a supplied coax cable for flawless performance. It's thoroughly tested on single slot boards only, probably works on others as well.
It will be released on Thursday(Jan 2nd) for pre-ordering on Beharbros.com, we can deliver them in 3 weeks probably.
The installation is so easy which requires a basic soldering skill, you may still need help from a modder/installer. We won't be providing installation services as we are very busy. It will be also used in our forthcoming Consolized MVS.
Price is $95 including shipping (DHL Express shipping (1-4 days) is optional for $10)
Package includes all cables,connectors and standoffs needed for installation.
Installation schematics will be released soon.