Sega Mega CD ISO Hacks & Editors

[Tony H]

Wow, making SCD codes can be very time Consuming. I'll include both the raw code, and the ISO hack info.

RDF: Global Conflict (U)

1 hit kills enemies...
With your hex editor, search for 6A00326700. Change the 6700 to 6000.
Raw code = 01EF62?6700:6000

--------------------

I'm still having trouble figuring out the addressing used in the asm logs. Example: I wanted to make a code to make the 7.62 gun stronger. I found that the 7.62 gun does 05 points of damage to enemies. I back traced the 05 value used in register D7 to this:

01:2320 3E 2A MOVE.w $001E(A2),D7 A0=00015158 A1=00015158 A2=0003969A

My 05 value is coming from 0396B8 (register A2 + 1E = 0396B8). In regular Genesis asm trace logs, this would be a straight ROM address, but not here of course. It might even be a RAM address. Can anyone shed some light on this? I suppose I could assume it's a RAM address and do a memory trace on it and see what shows up.

[rimsky82]

I got a present for you.

http://gamehacking.org/?sys=scd

I even added the first code.

http://gamehacking.org/?game=78525

Love, rimsky82. nohomo.

[Tony H]

Flashback (U)


Walk on air. Can walk across any opening without falling. Release the directional pad to drop down...
With your hex editor, search for the 10th occurrence of 660470FF. Change the 70FF to 4E75.

EDIT:

Walk thru walls, trees, etc...
With your hex editor, search for the 6th occurrence of 4A00660470FF4E757000. Change the 7000 to 4E75.
Part 2: With your hex editor, search for the 7th occurrence of 4A40660470FF. Change the 70FF to 4E75.

[Tony H]

Finally figured out how to find and make SCD codes without using Cheat Engine.

It looks like SCD memory tracing was disabled in Gens 9.5b, but it works fine in the regular Gens Tracer. I Used gens 9.5b to do the RAM search, then Gens Tracer to do the memory trace log.

From RDF: Global Conflict (1.20 ammo)...

[00:1DD6] W16 = 0000 [01D946]
[01B98] W16 = 0050 [01D946]

TRACE STOPPED

[01FA2] W16 = 004F [01D946]
[01FA2] W16 = 004E [01D946]
[01FA2] W16 = 004D [01D946]

TRACE STOPPED

As you can see, it shows the initial value of 50 being loaded, then 1 being subtracted every time I fired the gun.

[nolberto82]

If you are using MESS then the address is already given by the debugger. With Cheat Engine it depends on the emulator you are using.

[Mezmorize]

Awesome, that worked great.
How did you come up with the address?

[nolberto82]

Using this version of Gens you can enter cheats like this:

[COLOR="#0000FF"]Final Fight CD - Sega CD[/COLOR]

Semi Hit Anywhere
2100E6?6600:6000

Invincibility
21054A?6600:6002

[rimsky82]

I've never used a "cheat file" before. How do they work?

Emulators let you save cheats to a file. For the most part, they have different formats. Now at Gamehacking.org, you can download a generated cheat file for supported emulators for any game with codes.

MESS has a lot of involved setup, but is versatile. It has the same cheat support as MAME. Considering the amount of systems that it emulates, it's helpful to learn the debugger and hack with it. Especially since the debugger is native to the system it's emulating.

The downside to MESS besides the setup, is the lack of documentation.

[Hacc]

I've tried Fusion. It won't even let you try to enter any codes with Sega CD games. Have not tried Regen yet, but I already have the debugger version installed, so will give it a try.

EDIT: Fusion does however support all 32x codes.

EDIT 2: Regen doesn't support SCD.

OK. Ah, you're right. I forgot Regen doesn't support it or the 32x yet.

I made a code to always have rings for Sonic CD once. The code worked great, until the next level.

I think there are multiple instances because a lot of the routines are duplicated for each bank. Which, in the case of hacking, sucks majorly as it means multiple codes when the duplicated routines end up at different addresses.

Sega CD codes are going to take some hardcore testing I think.

The technical manuals are available for reading.

[Tony H]

Which means it will work in a cheat file.

I've never used a "cheat file" before. How do they work?

[rimsky82]

I made a code to always have rings for Sonic CD once. The code worked great, until the next level.

I think there are multiple instances because a lot of the routines are duplicated for each bank. Which, in the case of hacking, sucks majorly as it means multiple codes when the duplicated routines end up at different addresses.

Sega CD codes are going to take some hardcore testing I think.

[Tony H]

This is one thing I don't like, some games have multiple occurrences of a hex string.
I'm not gonna make 100% sure with each and every game that all instances should be patched.

I did fully test the game Sol-Feace, there were 7 instances for each of the 7 stages.
I didn't post the codes I had made for Sonic CD cause I never got around to testing, some hex strings were in the ISO like 50+ times.

Mez, I still remember that there were a ton of instances for my hacks with Sonic CD. I didn't even try to test them all. Gave up after the third or forth one.

@ Tony: Have you tried Fusion or Regen yet?

I've tried Fusion. It won't even let you try to enter any codes with Sega CD games. Have not tried Regen yet, but I already have the debugger version installed, so will give it a try.

EDIT: Fusion does however support all 32x codes.

EDIT 2: Regen doesn't support SCD.

[Hacc]

@ Tony: Have you tried Fusion or Regen yet?

@ Mez: They seriously named that game Wild Woody? I watched a review video (Taco-Man - Plays Wild Woody) of it and laughed in disbelief. There are two versions of this game, though. See The Director's Cut section.

Thanks for sharing that link, too. It took me a while to remember where I saw this link, but it will help greatly to understand and mess about with the system more.

http://www.retrodev.com/index.html

[rimsky82]

It worked in MESS with the following expression:

segacd:segacd_68k.ow@1E700=4E71

Which means it will work in a cheat file.

I did notice the address changing a bit as video was playing, etc. so we will need those compare values. The site will accept AAAAAA?CCCC:VVVV and AAAAAA:VVVV codes. I suggest using a compare for all asm patches. That should make it easier, eh? At least for the new site, you won't have to look up where to patch the iso.

Gens probably doesn't support writing to that address range.

[Mezmorize]

3 Ninjas Kick Back

3 Ninjas Kick Back (SCD)

Infinite Lives
Search: 426E009E610000CA4A6E00106730536E
Replace: 426E009E610000CA4A6E001067306002
19 occurrences.

Infinite Health (From Falling Spikes)
Search: 00806000303C00024EB900008FEE536A
Replace: 00806000303C00024EB900008FEE6002
19 occurrences.

Infinite Health (Ground Spikes)
Search: 001E0008670001244A6E009A660A536E
Replace: 001E0008670001244A6E009A660A6002
19 occurrences.

Infinite Health (Flame Thowing Wood)
Search: 4CDF408060326100E1646B2C4256536A
Replace: 4CDF408060326100E1646B2C42566002
19 occurrences.

Invulnerability
4A6E00886704536E00884A6E009A6704
4A6E00886704536E00884A6E009A6004
19 occurrences.

This is one thing I don't like, some games have multiple occurrences of a hex string.
I'm not gonna make 100% sure with each and every game that all instances should be patched.

I did fully test the game Sol-Feace, there were 7 instances for each of the 7 stages.
I didn't post the codes I had made for Sonic CD cause I never got around to testing, some hex strings were in the ISO like 50+ times.