Theme Park OCS background bug (ECS_Agnus option remedies it)

[djukon]

When running the Theme Park OCS/ECS version on a real OCS Amiga (with 1MB of RAM), does the background within a game become corrupted (starts red), or is it just on WinUAE? I don't have a real A500 to test this out on.

First I tried several combinations of Kickstart, RAM and compatibility options with no success. Only when I changed the OCS chipset to ECS_Agnus did I find that the issue went away. Supposedly this is an OCS compatible game, besides ECS.

I can't be sure of WinFellow, since I can't get beyond the first window where you are supposed to fill in the player's details. The mouse moves yet options don't get activated when clicked on, neither is it possible to write characters in the fields.

I discovered this issue on WinUAE 3.6.0 and I have tested it on 3.6.1 with the same result. I'm using the plain "Theme Park (1994)(Electronic Arts)" floppy images.

Could this be an OCS emulation bug or something else?

[BTW, I still have to look into how to share images on this forum.]

[Toni Wilen]

Include a screenshot. Even better is to also include statefile
(assuming it is disk based games)

[djukon]

Originally Posted by Toni Wilen

Include a screenshot. Even better is to also include statefile
(assuming it is disk based games)

Hi Toni, the game is booting from floppy disk images.

Starting the game, the background is red (it should have been filled in with grass tiles):


After scrolling around for a bit, this is the corruption result:


The save state is attached to this post in a 7z archive file.

For this run, I used an NTSC OCS A500 with KS1.2, just the first drive (DF0: write-protected), +512KB of slow RAM, and the most compatible settings (cycle-exact, full collision, wait for blitter); though changing those settings makes no difference. Changing to ECS_Agnus is the only setting I have found that overcomes the graphical corruption effect.

Sorry about not including the screenshots beforehand; I finally found the FAQ page on attachments and images so I don't incur in any faux pas.

[DamienD]

Does anything change if you use KS 1.3?

Edit: just tested, same thing happens with PAL / OCS A500 / KS1.3 / 512KB Chip & 512KB Slow RAM...

If I change to "ECS Agnus" then all good.

Since you're emulating though; why not just use "ECS Agnus"?

[Zarnal]

Hi,

Maybe 1Mo of Chipram required ?

Works perfect with KS1.3 + 1Mo Chip.

Edit : in Full ECS.

[Toni Wilen]

1M chip RAM and OCS Agnus does not really exist..

Game uses ECS-only blitter custom registers BLTSIZV and BLTSIZH to start the blitter. Which do nothing on OCS.

[Amiga1992]

Originally Posted by Toni Wilen

Game uses ECS-only blitter custom registers BLTSIZV and BLTSIZH to start the blitter. Which do nothing on OCS.

Going a little OT here but, can I ask: how should you start the blitter in an OCS compatible way that will also run on ECS/AGA?

[StingRay]

Just use standard BLTSIZE register.

[Amiga1992]

Originally Posted by StingRay

Just use standard BLTSIZE register.

Thank you!

[djukon]

Originally Posted by DamienD

Since you're emulating though; why not just use "ECS Agnus"?

I was just trying to see the results of running later software (>1993) on lower specs/older models and stumbled on this bug. From what I've read, if one intends on properly playing this game, they are better off sticking to the DOS version, since the Amiga ports of this game are not well done.

Originally Posted by Toni Wilen

Game uses ECS-only blitter custom registers BLTSIZV and BLTSIZH to start the blitter. Which do nothing on OCS.

Thanks, Toni. Does this mean that the game got through EA's QA without having been tested on an OCS machine? Or is there a particular revision of the game that runs properly on OCS?

On HOL, one of the box scan's says A500 as well as A2000.

[Amiga1992]

Originally Posted by djukon

Does this mean that the game got through EA's QA without having been tested on an OCS machine?

By the time this game came out I would be surprised if anyone cared about this running on OCS. Anyone probably already had an Agnus upgrade and/or full 1MB Chip RAM.
Doesn't matter what the box says, pretty surethis game needs 1MB Chip RAM (try to run an ECS config with 512kb slow+512kb chip and see what happens)

[Foebane]

Originally Posted by djukon

Thanks, Toni. Does this mean that the game got through EA's QA without having been tested on an OCS machine? Or is there a particular revision of the game that runs properly on OCS?

On HOL, one of the box scan's says A500 as well as A2000.

Maybe EA thought the A500 Plus was the same chipset as the A500, so they just released it as being for A500 without realising that there was a difference?

[djukon]

Originally Posted by Akira

Doesn't matter what the box says, pretty surethis game needs 1MB Chip RAM (try to run an ECS config with 512kb slow+512kb chip and see what happens)

As far as I've tested it, it seems to run well just by changing the OCS Agnus chip to the ECS variant. I made sure the memory configuration was 512kB chip + 512kB slow.

Originally Posted by Akira

By the time this game came out I would be surprised if anyone cared about this running on OCS. Anyone probably already had an Agnus upgrade and/or full 1MB Chip RAM.

I don't recall people I knew who had regular A500's doing an Agnus upgrade back in 1994. They usually just had the 512kB slow RAM expansion.

Originally Posted by Foebane

Maybe EA heard about the A500 Plus and didn't bother to see what was "plus" about it, so they just released it as being for A500 without realising that there was a difference?

I'm just surprised if this is the first time this issue has been detected. The A500 install base around the world in 1994 should still have been rather large for someone to have surely picked this out. This is not an unnoticeable bug: more than 50% of the screen is red when you start the game.

[Toni Wilen]

It is not the only game. There are other games that have glitches with OCS A500 but work fine with ECS. For example few have small sprite corruption (due to undocumented "free DMA slot next to first bitplane DMA slot is not actually available for sprites")

Of course I don't remember any names, I think one or two were reported as emulation bugs because sprite bug was not emulated until some later 2.x version

[djukon]

Originally Posted by Toni Wilen

[...]For example few have small sprite corruption (due to undocumented "free DMA slot next to first bitplane DMA slot is not actually available for sprites") [...] I think one or two were reported as emulation bugs because sprite bug was not emulated until some later 2.x version

Toni, does this mean that this particular Theme Park OCS issue might not occur on real OCS hardware due to some undocumented behavior? Thanks.

[Toni Wilen]

Originally Posted by djukon

Toni, does this mean that this particular Theme Park OCS issue might not occur on real OCS hardware due to some undocumented behavior? Thanks.

No, game requires ECS. I said undocumented hardware behavior, nothing to do with emulation.

[djukon]

Originally Posted by Toni Wilen

No, game requires ECS. I said undocumented hardware behavior, nothing to do with emulation.

Thank you, Toni. In that case, this means that the only option of the game running on OCS is if there is a different released version that does support OCS. Does anyone have or know of such a version?

Toni (as this sub-forum's moderator), since you have confirmed it not to be an emulation/WinUAE issue, might it be appropriate to now move this thread to the support.games sub-forum?

[DamienD]

Originally Posted by djukon

Toni (as this sub-forum's moderator), since you have confirmed it not to be an emulation/WinUAE issue, might it be appropriate to now move this thread to the support.games sub-forum?

Done

[Seiya]

many thanks. i tried and i see the same graphics issue with OCS chipset.
Initially i thought red grass was normal in OCS version :P

[DamienD]

Red grass normal?

God help anybody using your project then; must be top notch and tested to the absolute extreme; especially when you have correct references all over the place to go by

...see Seiya, two can play this game