Neo Geo Home Cart System Mod
There are several modifications that people typically have done to their Neo Geo Home Cart Systems.
Neo Geo Stereo mod
The first and easiest is the stereo mod. The cart systems sound is mono by default.
You can do one of two things to alter this.
- Plug a stereo jack into the headphone out jack. Then plug this into your stereo. Its that easy.
- Drill a couple of holes into the back of the case and place in some RCA jacks.
Then, run a wire from the jacks to the stereo amp and solder a connection.
This way you can just run cables from the back and you don't have them dangling in the front.
Neo Geo S-video mod
Probably the best mod in my opinion is the S-video mod. Typically Neo Cart Systems have poor video out.
Color bleeding and dot crawl are noticeable. By inserting an s-video jack into the case and wiring it to the video source on the motherboard you will achieve a much better picture. I highly recommend having this done as it really made a world of difference for me.
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Converting PAL Neo Geo to NTSC
- Remove the resistor that is located towards the top-right of the board, marked "PAL".
- Replace the video sync crystal with one that is rated at 3.579545 MHz.
- This is located in the top left area of the board.
- Change the PAL/NTSC setting of the CXA1145 video decoder chip. Usually (on all the newer style boards), you will see an NTSC jumper that is empty and a PAL jumper that is set. Just take the PAL one off and set the NTSC one.
Neo Geo Console Debug BIOS - Double Stack Installation Method
Last but not least is the "debug" or "MVS" mod. This is actually a complete BIOS change.
There are BIOS chips that have been modified to give you more control of your system.
No censorship, cheats, extra game options, etc. This is a very nice feature.
If you are comfortable with your soldering skills all you have to do is purchase one of these BIOS chips & replace the one on your board. You may choose between 2 different BIOS chips.
One boots the system in Japanese. The other boots as European/English. Japanese is the most common; the only drawback to it is the memory card option screens are harder to navigate.
Other than that it, doesn't make much difference.
Required Tools
- Phillips Screwdriver
- Soldering Iron
- Solder (.022 diameter preferred. Silver bearing solder will spread easier.
- Snips
- (1) 15K 1/4 watt carbon resistor
- (1) Small length of wire
Getting started
When you first open your Neo Geo, you will need to locate the original BIOS located on the PC board that resembles the chip that we have sent to you (in terms of pin count and size). Depending on the board revision, the BIOS will have one of the following chip numbers on it:
TC531024P
531024
It will most likely say TOSHIBA and will also have either NEO-EPO (USA Version) or NEO-PO (JAP Version)
SNK manufactured two “general” layouts of the Neo Geo home console board and the BIOS will be in one of the two following locations:
- Top-middle of the PC board – the chip is usually marked with the Toshiba or Hitachi name. It will also be marked with NEO-EPO or NEO-PO. The chip number will be TC531024P followed by the chip speed. Most Neo Geo home consoles have the BIOS in this location.
- Middle-right of the board. Same details as above, but this was a later revision of the Neo Geo console, and the BIOS is located more towards the middle of the board, off to the right. The chip number will be listed as 531024.
Installing The Debug Bios
- Unscrew the board from the Neo Geo casing.
- Locate the BIOS chip. Notice the orientation. The “key notch” will be to the left.
- Carefully, snip pin 2 as close to the board as possible and bend the pin out straight.
- Bend Pin 2 of the Debug Bios out flat as well.
- Carefully put the debug BIOS DIRECTLY on top of the existing bios chip. Make sure all pins are aligned and that the (2) #2 pins are both straight out and not touching each other.
- Go around and solder all 39 pins in place. Make sure you don’t get too much solder on the pins making them contact neighboring pins.
- Using the resistor, solder one end of the resistor to pin 2 of the BOTTOM BIOS (the original BIOS) and then bend the resistor around and solder the other end to pin 40 of the BIOS stack. Note that Pin 40 on the top and bottom BIOS’ are already connected, so just solder to this area. Use Figure A as a guide.
- Using the small length of wire, solder one end of it to pin 2 of the TOP BIOS and solder the other end to pin 20 of the BIOS stack.
- At this point, you should be done. Gently insert a cartridge into the cart port to make sure that no wirework or the resistor will be in contact with the cart when it is fully inserted. If so, just move the wire or resistor so that the cart will have a clean path in the cartridge port.
- With the cart in, power up the system to make sure the new Debug BIOS works. If your machine does not boot into the Neo Geo boot screen, promptly turn the unit off and double check all connections!
- Reassemble the system.
- Done.
To activate the Debug Bios Menu, press “Select + C” on controller 2.
Disclaimer: You are assuming all risks by installing this replacement BIOS. If not done properly, you can damage your Neo Geo. If you don't have the tools or experience, you can seriously damage the unit. By opening your Neo Geo to install this replacement BIOS, you agree to assume all the associated risks.
Note:
- I do not do any of these mods myself. Therefore all info here is for your information only.
- I take no responsibility for any damage you may inflict upon your system or yourself.
- Unless you are very sure of yourself, I recommend that you have any mods done professionally.
Neo Geo Home Cart System
In the 1980s the Shin Nihon Kikaku (SNK) corporation was a 3rd party game developer for the 8bit Nintendo Entertainment System. With such hits as the Ikari Warriors and Baseball Stars, SNK was a hot commodity. However, SNK wanted more so in 1989 they released into the Japanese arcades the 16-bit Neo Geo MVS. When they did this, they also took the arcade motherboard and placed it in a console shell. Thus we have the Neo Geo Advanced Entertainment System, otherwise known as the Home Cart System.
This console was originally slated as a rental only unit in Japan. Due to a huge demand by their customers, SNK killed the rental model and in 1990 released the Home Cart to the general public for a hefty $650 + $200 per game. This price was outrageous to many, but you have to remember that this was an extremely expensive machine to make. Building ROM cartridges are still expensive to this very day.
Back in 1990 all the parts were expensive, much more than any previous console. SNK never intended to sell retail, the Neo Geo was arcade hardware and it showed. This was also a blessing. The Neo Geo AES was the baddest game console and it really made the competition look pathetic. With games like Nam-75 and Crossed Swords in the arcades, many arcade gamers wanted these great games in their homes.
Compared to the cost of the MVS setup the Home Neo was quite a bargain.
The Neo took off to be one of the more popular systems, but was relatively unheard of in the USA until 1993.
Enter Samurai Shodown. This game hit the arcades like a flashfire. It was very popular in arcades and was not eclipsed until Samurai Shodown 2 in 1994. This is the one time when SNK was more popular than Capcom's blockbuster Street Fighter series. At least in the US that is.
In Asia, SNK has been strong competition at every turn.
Known for its fighters, but also loved for its puzzle and shooter games, the Neo Geo is a great game system that appeals to many! Almost all Neo games are designed for pay for play action, so if you're looking for rpg's or in-depth strategy games, you are better off looking elsewhere.
Specs:
Processor: Motorola 68000 (12 Mhz), Zilog-80A (4 Mhz)
Resolution: 320x224
Color Palette: 65,536
Maximum Colors On-Screen: 4,096
Maximum Sprites On-Screen: 380
Minimum Sprite Size: 1x2
Maximum Sprite Size: 16x512
Maximum Planes: 3
Sound Channels: 15 (7-Digital, 4-FM synthesis, 3-PSG, 1-Noise channel)
Internal RAM: Work RAM: 64 Kb Video RAM: 68 Kb Z80 RAM: 2 Kb
Save Memory: Removable Memory Card
