Boot a specific game from a Collection one directly on startup?

Started by ShadowOne333, September 22, 2014, 05:05:14 PM

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ShadowOne333

Good day, community.

I had in mind for quite some months now this idea.
You see, we know that there are some compilation or collection packs or games out there that hold some extras or some feature that the original game did not have.

My idea is to try to do one of the following two:

  • Extract the specific game rom out of the file
  • Make a pointer of some sort (or something else) to make the game or rom boot directly into the game you want to play without going through the menu selection.

This is so we can have a standalong ROM of such game instead of the whole package in the collection.
One clear example (and my goal) is the following:




To have a standalone color ROM of both Castlevania The Adventure and Castlevana II: Belmont's Revenge for the Gameboy Color.
The originals were great, but the addition of color makes them standout wondefully.
Also, all the hacks that have been made to the original monochrome games also apply to these versions, so getting a standalone rom for these two will also embrace those hacks too!

Is there a way to hopefully make the Konami Collection games boot straight into those two?
Or is there a way to extract the coloured rom?

Any kind of help will be greatly appreciated!

FAST6191

Depending upon the original console, the console/device they are being run upon now, the whims of the developers on the day and more besides this can get tricky, though it is worth trying a few things as there are often fairly simple things that can be done.

First though it has to be noted that such collections might not be plain emulation of the game, and if they happen to be emulators then said emulators might be game specific and include a bunch of extras on top of that. Generally speaking then as machines get more powerful then the chances of something being actual emulation you can extract a ROM* from go up -- the Wii virtual console saw a lot of this. However remakes are possible and if the source code is available (and not just a bunch of assembly) then they can recompile games to work on new platforms.

*do note that it might technically be a ROM image but it might not be one standard emulators, flash carts and modding techniques accept. Sega's stuff did some things along those lines.

Pointers wise I usually see one of two things
1) The devs make what almost amounts to a flash cart or tourist trap/lucky lucky man multigame cart and kind of, or indeed actually, soft reset into the game. The GB/GBC did feature a reasonable banking setup so this gets even easier for a would be dev to do. In some instances the cart may even have a dip switch or some kind of hardware switch on it to change what boots.
2) The devs recompiled/tweaked it to work from a new, different, address and soft branch to it at some point. The trouble may come in that the game needs the new loader screen to set some stuff up first (see initial IO from any introduction to assembly document you care to read) but that is usually nothing major.

Each have their quirks. In both cases you want to be looking at the selection screen and what the game does to select it. For the flash cart approach I would look branching/jumping to the function and letting the game handle it, for the soft branch approach you can hopefully get away with doing your own branch at a suitable point. I tend to see 2) more for when there are just collections of games (think all those card/puzzle games), bonus modes and the like but people want to have a version that boots directly to those.

"Also, all the hacks that have been made to the original monochrome games also apply to these versions, so getting a standalone rom for these two will also embrace those hacks too!"

Interesting, I assume you mean that the old patches work as if they were the same thing rather than the hack authors spun off another patch to cover both versions. If I had to guess why that is I would say they might have left the original game in place and modified it accordingly (make it appear as a GBC game, have it boot in the GB clockspeed mode of the GBC* and boot game but have colours set, however leave all the level, graphics and music data in place). Konami these days seems to employ some coders of... variable talents but that will get a passing nod from me, even if it is just a workaround.

*they might have fixed the sync issues when using double speed, I would not do that unless I really had to though and adding some colours should not have necessitated that.

dACE

There are 'speed-up' patches for the two colored versions of castlevania adventure, I think the hacker Drakon made the one for Belmonts revenge.

He also made a 'Makro-hack' - that automatically selects the castlevania game from the collection menu. The downside of that hack is that it doesn't boot castlevania directly - you have to watch all menu selections being done for you.

His hack might be a good start to look for clues - it should be somewhere on this site...

Edit:

Here it is: http://www.romhacking.net/forum/index.php?topic=17446.0

And here is the speedhack for castlevania adventures: http://www.romhacking.net/hacks/190/


/dACE