JAMMArcade.net

Well today I finally finished the conversion.
Ive been doing the title screen conversion over a few days as its a very boring task

As you can see, the palette isn’t correct when originally copying the image over so this has to be changed manually after its all complete.

Once complete though, its identical to the original

All the graphics have been changed to original RI ones and plays pretty much the same.
There are still a few differences:
1. Some of the DIP switches do nothing.
2. Every now and then the sprites when a monster is killed are messed up. Cant locate the code where its going wrong.
3. Secret rooms do not work.

I can honestly say all of the images were taken from my conversion in MAME and not from the actual Rainbow Islands ROMs.
I haven’t actually tested it on the real hardware yet so it may not work the same as it does in MAME though. Fingers crossed it does.

Today I finished off the main character sprite. After that I started work on restoring all the title screen text.
Getting the standard copyright info back was a simple task of replacing the “1989″ text in the ROM file with the text from the real Rainbow Islands ROM.

Ignore the title screen image, I made a start on changing the graphics just to see what the colours would be like.
So the text is back but there is also a red Taito logo missing. After much searching it turned out that the logo is actually being drawn but its palette is set to black so is not shown. This explain why I saw it on my real board when fault finding a colour issue.

Following the same routine I used for changing the character palette I found the value at address $229E8 and changed it from 00 to 3E which after the bitshift routine, sets the palette to 000F (Red)

And with that done I think all that is left to do is finish off replacing the graphics tiles for the title screen. This may take a while and will probably end up adding a little something to it just to set it apart from a genuine board.

I am aware that on this bootleg the secret rooms do not work. This is because the C chip is not present on the board and there is little I can do about that. Overall its been a fun little project.

Carrying on with my conversion….
I quickly replaced the graphics for the 2 world names that had been changed.
The first island was renamed to “Fly World” and the second was renamed “Army World”

Both have been restored to their original names along with “The Rainbow Islands” text.

Next on the list was to change that horrible looking main character sprite back into Bub (or Bob).

This looked like it was going to be the familiar task of replacing the graphics and changing the colours to match the palette, I was wrong.
When I changed the sprite graphics back I could not match the colours of the original so the bootleggers must have changed the palette. So where is the palette information stored?
Looking at the MAME source revealed all.

As you can see the palette info is stored in RAM between locations 0×200000 and 0x200fff.
So I went to the MAME debugger and started filling this area of RAM with random numbers until I found the area that changed this sprite palette.
The WORD location for this is at 0x20027C and after trying different values I found one pretty much identical with a value of 001D.
So how do I get this to load into RAM every time? Back to the debugger.
Jumping has some bizarre code at address $386 onwards that sets the palette. Its bizarre in that is performs a series of bitshifts to get the values it wants.

So…
The palette value is stored in ROM at location $23630. It takes the value at this location, does its bitshifting routine and the output of that is its final value.
Seeing how this was done I inserted the value I wanted (1D) and manually working it out backwards until I had a value to replace in the ROM.
The original value was 03DE and my new value needed to be 005A.
After inserting it into the ROM and testing I went from this:

To this:

Time to call it a night.

After playing my RI bootleg, Jumping, for a bit I came to the conclusion that despite being essentially the same game it just didnt feel the same with the crappy graphics that had been squeezed in.
I first started wondering about a conversion when I was fixing the Jumping board up and during my tests I found that a lot of the original graphics were still present.

I started out by doing the easy stuff first, changing the text back from “Jumping” to “Rainbow”. The bootleggers had even changed the credits list to different names, all this was changed back. So far so good.
My next step was to see if I could fix that stupid boot screen that normally says “Rainbow Project”. On the bootleg its just a repeating red pattern.

Armed with a couple of instances of MAME and its excellent debugger I set about looking for the changes.

At location 234E on the original it runs a sub routine which loads the background into memory – jsr $113da.l
On the bootleg, this has been NOPed out. Looking at the code this subroutine is still present, just bypassed.
I re-enabled this sub routine and tested the game.

As you can see it was a partial success but looking in the mame GFX viewer its clear than some of the graphics were replaced to make that crap title screen.
The background is still obviously messed up so went looking for that tile first. I found it at location $B6B and after changing it I had this:

Now, to replace the graphics I have 2 choices. Try and figure out how to manually read the ROMs or use a graphics editor of some sort.
The first option is not really an option at all cause im a little too impatient for that.
The second option is the only real way forward and there are a couple of bits of software available (excluding AGE).
The first is an old MS-DOS program called Turaco and the second is its command line update called TuracoCL.
As TuracoCL doesnt work properly for me I was stuck with Turaco.
The program runs fine in DOSBox and the process of copying the graphics tile by tile is very slow and tedious but I cannot find another way of doing it yet.

Now after a little while I finally got the first part of the challenge done and was happy with the outcome.

Comparing this with the original RI screen showed I had made a little alignment error on the A so I went back and fixed it.

Changing the title screen image is a pretty long boring task so Im actually gonna leave that till last.
Next up is to change a couple of the world names back. “Insect Island” is called “Fly Island” and “Combat Island” is called “Army Island”.
After that I will change the main sprite and the Rainbows back THEN its on to the title screen.
More to come…..