Although no one has found multiplayer code in Mario’s Tennis so far, I decided to take a look for myself. So first I modified an emulator to to help me identify data and code sections. Then I spent a while playing the game to collect enough data and to identify unused code paths. Next, I wrote a disassembler that was able to disassemble the whole game by using the collected data.
After taking a first look at the unused code, I was surprised to find quite much code that looked like proper multiplayer code. So I spent some time doing an in-depth analysis of the code and eventually I was able to reintegrate it into the game. A first test revealed that the controls of one of the players were inverted. This was probably done by the developers for easier testing. Unfortunately, the proper code bits were probably removed by a compile switch, so I had to rewrite them myself.
So far, I got 2 of 3 game modes (P1 vs P2 and P1/COM vs P2/COM) working properly. The third mode (P1/P2 vs COM/COM) is buggy and I probably won’t fix it anytime soon, because debugging and testing is too time-consuming without an emulator with link cable support. But once I have the necessary tools, I will try to fix it. Till then enjoy the first version of my patch. To apply the patch you have to use the tool bspatch.

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1. multiplayer_v1.bspatch

[mellott124]

I couldn’t resist. Here’s my version. The graphic design was done by another PlanetVB member.

• This reply was modified 7 years, 4 months ago by mellott124.

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M.K. wrote:
So first I modified an emulator to to help me identify data and code sections. Then I spent a while playing the game to collect enough data and to identify unused code paths. Next, I wrote a disassembler that was able to disassemble the whole game by using the collected data.

That’s a cool approach. I’m wondering if other games have more unused code as well. Faceball might have multiplayer code hidden somewhere after all.

It is pretty crazy that you managed to reactivate the multiplayer code. I played it with my wife for a bit. I noticed some balls getting lost right when they were over the net though. But maybe that was just my link cable or something.

thunderstruck wrote:

M.K. wrote:
So first I modified an emulator to to help me identify data and code sections. Then I spent a while playing the game to collect enough data and to identify unused code paths. Next, I wrote a disassembler that was able to disassemble the whole game by using the collected data.

That’s a cool approach. I’m wondering if other games have more unused code as well. Faceball might have multiplayer code hidden somewhere after all.

It is pretty crazy that you managed to reactivate the multiplayer code. I played it with my wife for a bit. I noticed some balls getting lost right when they were over the net though. But maybe that was just my link cable or something.

Hi Thunder,

Shouldn’t be the link cable. It would probably stop the game or you’d loose control completely.

Kevin

I am no good at this but I figured it was something to do this morning. My take on a new label. Feel free to comment on likes/dislikes.

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Wow this is a dream come true. Lets put Birdo in the game again and relese it as cart. I really want this as a cart version. Anyone how can put this on cart?

[e5frog]

Among others, mellott124 has a cart base, he should be able to make a real cart of it.

Virtual Boy Cartridges

Making a PCB isn’t that hard, it’s a lot harder to find donor carts for a reasonable price. Unless you have cash and can buy boxes of them from Japan or something like that.

The guy who had loads of Baseball carts is still portioning them out I guess?

• This reply was modified 7 years, 4 months ago by e5frog.

thunderstruck wrote:
I’m wondering if other games have more unused code as well. Faceball might have multiplayer code hidden somewhere after all.

I spent several hours checking other games (including Faceball), but unfortunately I didn’t find any traces of unused multiplayer code.

thunderstruck wrote:
I played it with my wife for a bit. I noticed some balls getting lost right when they were over the net though. But maybe that was just my link cable or something.

Are you sure that the ball disappeard for no reason?
If there is a (serve) fault and the opponent returns the ball despite the fault, then the ball usually disappears somewhere around the net. Take a look at a serve fault here: https://youtu.be/mXbPchEiptM?t=56

yea carts of this would be awesome and def needs to happen. hoping that 3rd mode gets fixed one day

M.K. wrote:

thunderstruck wrote:
I’m wondering if other games have more unused code as well. Faceball might have multiplayer code hidden somewhere after all.

I spent several hours checking other games (including Faceball), but unfortunately I didn’t find any traces of unused multiplayer code.

thunderstruck wrote:
I played it with my wife for a bit. I noticed some balls getting lost right when they were over the net though. But maybe that was just my link cable or something.

Are you sure that the ball disappeard for no reason?
If there is a (serve) fault and the opponent returns the ball despite the fault, then the ball usually disappears somewhere around the net. Take a look at a serve fault here: https://youtu.be/mXbPchEiptM?t=56

Might have been just that. Never saw it happening before.

this is really neat. thanks for taking the time to make this happen.

Since I found the others to not be very readable at small sizes, here’s another take at a GameLink logo.

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KR155E wrote:
Since I found the others to not be very readable at small sizes, here’s another take at a GameLink logo.

Nice. I like that one. I agree some of the others won’t print well at the VB cart size.

I made mine to blend in on the scanned label, it’s in 1200dpi – and it’s a very small mark on the label. I removed “GAME PAK” so it would look “less GameBoy”, have never heard anyone call Virtual Boy cartridges for “Game Pak” but it might be the official in the instruction booklet name?

So Krisse’s would be something like 2400?

The one mellott124 made (but was posted by someone else) is a bit too simple than I think Nintendo would have made it.

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A’la Krisse:

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I’ve read TeleroBoxer also writes out to the gamelink port. Has that rom been combed over? The only other one mentioned was Mario Tennis so good chance Teleroboxer has multiplayer??

This is amazing! I would really like to play 2 player games!

Two player Teleroboxer would definetly be amazing IMO. I purchased that game when it was priced at $5 when VB was pulled from the market and it is my favorite of the released games.

I could see Teleroboxer becoming the ultimate official 2 player game.

Ohhh man, multiplayer Teleroboxer would be the best.

This find and the patch are AWESOME!! Can’t wait to pick up my cable from the customs office 🙂

Here also comes my ‘offical submission’ for the GameLink logo 😉
Credits: I used KR155E’s logo and Hedgetrimmer’s controller 3d model to render these previews.
It could also be drawn as a high res vektor logo without too much work, I think …

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