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-   -   Issues with WHDLoad install of Oscar AGA (gamebreaking-bug) (http://eab.abime.net/showthread.php?t=99499)

ReL0aDed 04 November 2019 00:16

Issues with WHDLoad install of Oscar AGA (gamebreaking-bug)
 
This game seems to be working and all on the surface, but the game is in my experience broken as soon as you play the first stage of the War Level.


You start on the far left of the level, and have to progress through the water that's below you and under-water smash a breakable wall with a jojo-item to progress any further.


The problem is that the underwater wall is indestructible on the WHDLoad version of Oscar AGA, so there's no way to progress any further on the War Level.


In the disk version of this game, the wall breaks and all the water in this section disappears under the ground, leaving an opening for you to progress further in this level.



Strangely, I haven't found any topic on the web mentioning this issue; it seems like this game may have not been playtested thoroughly enough after the WHDLoad config was made (or that somethings wrong with my install).

Gzegzolka 04 November 2019 05:58

I have noticed same thing. I have my copy of Oscar aga from whdownload site. Original disk version do not have that issue. Maybe it is old version?

jotd 04 November 2019 08:04

probably a very old install. And maybe a very smart copy protection bug :)

Slave is from 2001... You can check the CD32 version which probably doesn't have any vicious protection and is also supported by whdload.

CFOU! 04 November 2019 11:42

Quote:

Originally Posted by jotd (Post 1356405)
probably a very old install. And maybe a very smart copy protection bug :)

Slave is from 2001... You can check the CD32 version which probably doesn't have any vicious protection and is also supported by whdload.

Indeed, it looks like the resurgence of a protection (missing cheksum rip/test protection key no removed)

.
ps:
it reminds me bubba&Stick, if key protection was not registered in memory, the end of the level crashed! or pang, lost patrol, snow bros,......)

jotd 04 November 2019 23:53

And Cadaver, Gods, Formula One (Micropose), Sinbad, LOTRS, Leander... lots of examples. The CD32 version should be devoid of that check since it doesn't use any protection (they thought noone would be able to burn a CD or make it run on a standard amiga probably)

ReL0aDed 05 November 2019 03:45

Thanks for all the replies.

I now tested out the WHDLoad version of Oscar CD32, and the very same issue is present there as well. The Slave is indeed from 2001 in both the AGA- and CD32 WHDLoad of this game.

I suppose this may not be an issue that derives from old copy protection then?

xubidoo 07 November 2019 17:44

They probably just straight chucked the AGA game lazily onto the CD32 without bothering to remove the protection, hence the same problem.

to be honest ive never got that far to have that problem :D, as i never thought much of the game.

Have u opened a Mantis bug report?

jotd 07 November 2019 22:32

Quote:

They probably just straight chucked the AGA game lazily onto the CD32 without bothering to remove the protection, hence the same problem.
I'd be very surprised about this. Is there a way to reach this stage quickly? I have a CD32 and original version of Oscar, I can also test this.

Opening a mantis bug is a good idea.

ReL0aDed 08 November 2019 23:48

War Level 1 is in fact the door in the big hallway with the War image on, so it's as quick as accessing the other levels.

I'm not a super huge fan of this game myself, all I can say is that nostalgia is a powerful drug (all the enemies are the same but in various shapes and they respawn all the time + the level design is unforgivable at times)

I'll submit a Mantis bug report as soon as I get my verification em-mail in return, as I just recently registered an account there.

ReL0aDed 09 November 2019 01:05

Aaaand mantis bug report is now submitted.

Maybe this will be fixed now, eventually? =)

jotd 09 November 2019 12:06

I definitely have an interest testing & fixing this. A lot of projects right now, but let's see if this can be done easily.

CD32 plugged in with oscar in drive. And wall can be broken all right if you have the mojo. The longplay shows that too. https://www.youtube.com/watch?v=chcehaCIMAA

jotd 10 November 2019 00:28

Update: bug confirmed. On real CD32 and emulated CD32 ISO using winuae CD32 config it works well

With all versions of whdload I've tried it fails (under winuae). The mojo is launched but goes through the blocks without breaking them. It's not a copy protection issue, rather a whdload issue. Or there are checksums in the CD32 version too...

I helped Codetapper to fix superfrog project F a long time ago. Whdload writes $F0000001 in $4.W so if programs wrongly read this location (byte at 4) and stumble upon a non zero value like F0 (negative) it could fail. That's what happened with project F.

Unfortunately, it doesn't fix the Oscar issue... And same thing running through JST. Note that the mojo works: you can cling on platforms and break the blocks of the bonus room on top of the elevator at the start... Fishy.

EDIT: quickly adapting another CD32 kick31 emu slave (from chaos engine source, without any patches) to bundle CD version of Oscar 1) works 2) fixes the issue... So there's hope for a clean fix now (this slave could be a "CD32 generic" one BTW). One hypothesis would be that the code checksums aren't tripped because the game isn't patched at all.

jotd 10 November 2019 12:30

Found the issue in whdload.

Bert changed adda.l -> adda.w somewhere probably to avoid access faults when D1 was too high (probably collision related)

PL_W $1ce6,$d0c1 ;adda.l -> adda.w


BUT at some point D1 is > $8000 and adda.w uses D1 as SIGNED. In that case the proper fix is still use adda.l but mask D1 prior to adding.

This slave needs dusting anyway. With 2 button support & joypad support. There are 4 versions but they seem very similar.

Wepl 12 November 2019 23:39

Thanks for fixing it :)

Seiya 13 November 2019 00:40

i confirm that this issue don't work also on A1200 AGA WHDload version..(winuae)

jotd 13 November 2019 00:45

all whdload versions have this bug since 2001. I guess this game ain't that popular, despite really nice AGA gfx. Anyway, update will be on whdload page soon. With trainer added.

Reminds me of Immortal slave that was broken at the last level... I noticed & fixed that last year after almost 20 years...

I was contemplating adding 2nd button for jump but that's some work for a game noone cares for.

ReL0aDed 13 November 2019 05:10

Great; thank you for fixing this bug.

Personally, I usually bind the jump button to the A-button on my Xbox One gamepad while playing Amiga games on an emulator (I'm currently using the P-UAE libretro core in RetroArch for Amiga games).

ReL0aDed 14 November 2019 01:52

I've tested out the newest revision of this WHDLoad install (both on the AGA and CD32 version), and the wall is now breakable =)


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