The X68000 games porting experiment

[Anima]

Galaga 88 video

Cheers
Sascha

[CiH]

Sweet! - See what you mean about the slowdown though.

[Anima]

Sweet! - See what you mean about the slowdown though.

It seems that the sprite data copy algorithm of the original code causes this so there's room for some improvement.

Cheers
Sascha

[EvilFranky]

Outstanding!!

Sent from my GT-I9100 using Tapatalk 2

[Cyrano Jones]

Just watched the Galaga 88 video - really impressive stuff!!!

I assume the slow down is because of the amount of sprite data sent to the screen, all that and/or nonsense takes its toll, especially at higher bit depths.

Do you plan on making the source available for these? I'd love to have a go at getting Galaga on the Jaguar! While it's only got 2mb, as sh3 said, it's got 2-6mb of ROM, plus there is no need for a frame buffer, or shifted sprite data, as the hardware can do all that.

In any case, well done!

[Anima]

Just watched the Galaga 88 video - really impressive stuff!!!

I assume the slow down is because of the amount of sprite data sent to the screen, all that and/or nonsense takes its toll, especially at higher bit depths.

Do you plan on making the source available for these? I'd love to have a go at getting Galaga on the Jaguar! While it's only got 2mb, as sh3 said, it's got 2-6mb of ROM, plus there is no need for a frame buffer, or shifted sprite data, as the hardware can do all that.

In any case, well done!

Hello Cyrano,

the slowdown is mainly caused by the limited sprite hardware memory which is constantly refreshed while playing. So removing this behaviour would result in a good speedup because it's not necessary for the Atari port!

However, I'd like to see Galaga 88 running on the Jaguar as well because the Jaguar totally deserves such a game.

Tell me what you need. We can go on with the discussion via PM. What do you think?

Cheers
Sascha

[Cyrano Jones]

PM sent! Lets Galaga up the Jag

[dml]

Haha, that's very cool.

At what level is the emulation working? Everything - or can the graphics stuff be abstracted in some way and made more host-specific?

[Anima]

Haha, that's very cool.

At what level is the emulation working? Everything - or can the graphics stuff be abstracted in some way and made more host-specific?

Simply all hardware registers have been mapped to RAM. Of course the game runs natively like on the X68000 so there's no slowdown on the gameplay itself.

The X68000 has a very clean interface for sprites and graphics which makes it easy to implement your own display routines.

The hardest part is to disassemble the program to have a good source for modifications especially for the hardware register to ROM mapping task. In fact, only about 30 lines of code have been modified to get Galaga 88 running on the Atari (slightly more than PacMania). Remember: I am testing the disassembed output first with the Human68k toolchain. The resulting binary needs to run on the X68000 like the original. After this step I can take the source for the port.

So in conclusion I hope to see X68000 games running on the Firebee in a window.

Cheers
Sascha

[papa_november]

This is insane and a miracle.

What about going the other way? I'd love to play OIDS on my X68000.

[Anima]

This is insane and a miracle.

What about going the other way? I'd love to play OIDS on my X68000.

This would be in general the same. Of course you will face some other problems like the really strange Atari bitmap graphics layout but this is not a stopping barrier.

Cheers
Sascha

[Anima]

Hello guys,

just a short Galaga 88 update:

I am still in the process of renaming labels because I need to find a good cheat to get to the higher stages easily. The renaming is rather difficult due to the excessive address relative memory access usage.

It seems that even with an optimized sprite routine the frame rate will drop on a 16 MHz Falcon when many sprites are visible.

I have also found bugs in the source code but I am not yet sure how the gameplay differs to a version without these bugs.

Cheers
Sascha

[CiH]

It seems that even with an optimized sprite routine the frame rate will drop on a 16 MHz Falcon when many sprites are visible.

Thanks for keeping us posted here.

So we'll still get slowdown on Galaga 88, but hopefully not to the point of starting to choke in places as illustrated on the Youtube video?

I guess that hardware acceleration, where available, will help here as it did with the Pacmania preview

(Also any chance of Pacmania reappearing at some point? It looks very nice on the Falcon, almost arcade quality.)

[wongck]

Whoa.... Hot Stuff !!!
Keep up the good work !!
Think of all the other ports that will be possible!!!

Even with the slowdown, it is a amazing step forward !!!
The slowdown.... equate to something like bullet-time so you can think what the next step to take

[sh3-rg]

[quote="wongck"The slowdown.... equate to something like bullet-time so you can think what the next step to take [/quote]

Galaga Tactics? I'd play it

I've been looking at x68000 games, hoping to find translations of some lower-action games such as the RPGs like the Ys games - no luck, there doesn't seem to be much of a translation scene for x68000. Away from RPGs it was difficult to find anything that might not be too taxing - Shanghai is a good game, but the st/falcon already have similar games.

[Anima]

So we'll still get slowdown on Galaga 88, but hopefully not to the point of starting to choke in places as illustrated on the Youtube video?

I guess that hardware acceleration, where available, will help here as it did with the Pacmania preview

(Also any chance of Pacmania reappearing at some point? It looks very nice on the Falcon, almost arcade quality.)

Currently the slowdown on a 16 MHz Falcon goes down to half of the full framerate so the playability is still very good. So with an acellerator you should have always the full framerate like the original.

PacMania will definitely benefit from the Galaga 88 optimizations as well so stay tuned on PacMania news.

Even with the slowdown, it is a amazing step forward !!!
The slowdown.... equate to something like bullet-time so you can think what the next step to take

The slowdown makes the game a lot easier so it is important to optimize it for the 16 MHz Falcon to have a good game experience. I hope this goal is still achievable.

I've been looking at x68000 games, hoping to find translations of some lower-action games such as the RPGs like the Ys games - no luck, there doesn't seem to be much of a translation scene for x68000. Away from RPGs it was difficult to find anything that might not be too taxing - Shanghai is a good game, but the st/falcon already have similar games.

This is indeed a big letdown on porting from a japanese only system. Probably I should switch to Sega Genesis, NeoGeo or M68000 based arcade games.

Cheers
Sascha

[dma]

Impressive work indeed, glad to see you're succeeding in your ideas!

By the way, talking of gaming systems ports, someone ported Mario Bros to Genesis: http://devster.proboards.com/index.cgi? ... thread=613
Maybe this could be converted to STe (needing certainly a similar adaptation work to be done concerning graphic and audio management system)?

[sh3-rg]

Impressive work indeed, glad to see you're succeeding in your ideas!

By the way, talking of gaming systems ports, someone ported Mario Bros to Genesis: http://devster.proboards.com/index.cgi? ... thread=613
Maybe this could be converted to STe (needing certainly a similar adaptation work to be done concerning graphic and audio management system)?

Converting a Mega Drive game that was originally a NES game to the Falcon (or ST, which seems less likely) sounds like a great idea to me

Mairtrus, the guy who converted the game from NES to MD, was kind enough to send me his mos2mot tool (6502 to 68k source converter) and some instructions after I contacted him regarding his release. He's a very kind and informative chap, the sort of person who will go out of his way to help you if you ask him. A few Jaguar coders have wanted to give it a go to bring mario to that machine, but nobody has had enough free time from their own projects so I've just sat on it and felt a bit guilty about that. Doing a search just now I see he's released it publicly just a few months ago: http://gendev.spritesmind.net/forum/vie ... ght=#16075 So if someone fancies a bit of 6502 to ST/Falcon game converting (it's not just pressing a button but he said it'll do a lot of the manual work for you, of course you need to work on the machine-specific stuff but all your game logic comes free). Working directly with the MD game might be simpler, I don't know, but I thought I'd mention the tool here since DMA reminded me of the port, and if it sets someone off on the path to bringing old 8-bit conversions to the ST or Falcon, great

CJ and another ex-ST-now-Jaguar coder have hinted that they'd like to bring some games form Mega Drive at some point, Mario Bros will deffo be one I push for Of course, all Reboot stuff is there for GGN to take to the Falcon if he's feeling that way inclined as he did with Downfall, but it'd be nice to more converted games appear on the Falcon whoever does them I think.

[Cyrano Jones]

x68000 to Jaguar is going to be interesting. The x68000 has 1mb of video RAM, that doesn't leave a lot of room for everything else!

I'm not saying it's impossible (because it isn't) but it is going to take quite a bit of effort to do these on the Jaguar, and right now I don't have the time to invest in this. The Genesis brings it's own fun issues, as the screen is composed of layers of 8*8 tiles in one of 4 palettes.

Anima - thanks for the source, I was hoping these would be fairly quick to port, but that's not the case. I promise I'll look at them in the future though!

[NGF]

Just watched the videos, looks very promising

[Anima]

x68000 to Jaguar is going to be interesting. The x68000 has 1mb of video RAM, that doesn't leave a lot of room for everything else!

I agree with Cyrano.

Some technical background on the main problem he is talking about.

The X68000 has very "interesting" video access modes for the background graphics memory. In fact, the total physical graphics memory size is 512 kb but it consumes up to 2 MB of the hardware register space. This depends on the number of colors and planes the game uses.

512 kb (65536 colors mode): one 512 x 512 pixels plane, 16 bit per pixel, direct color mode comparable to the "true color" mode of the Atari Falcon.
1 MB (256 colors mode): two 512 x 512 pixels planes, 16 bit per pixel (but only the lower significant byte can be used, indexing a 256 colors palette).
2 MB (16 colors mode): four 512 x 512 pixels planes, 16 bit per pixel (but only the lower four bits can be used, indexing a 16 colors palette).

Galaga 88 uses the 256 colors mode with two planes. The first plane is used for the graphics and the second for the moving stars animation in the background. So in fact only one 256 color plane needs to be "ported" for the game and due to the fact that only the lowest byte is used the real memory requirement is actually 256 kb. With more work this can be lowered even more considering that only 1/4 (256 x 256 pixels) of this plane is visible on the screen resulting in 64 kb memory usage.

In conclusion porting to a system with limited memory requires heavy modifications/stripping of the source and this needs a good "readable" source.

So far I don't care about this problem on the Falcon port: "only" about 7.5 MB of the 14 MB RAM is currently used for the game.

Cheers
Sascha

[wongck]

Currently the slowdown on a 16 MHz Falcon goes down to half of the full framerate so the playability is still very good. So with an acellerator you should have always the full framerate like the original.

Does that mean.... does that mean it will run on a CT6x??

[Anima]

Does that mean.... does that mean it will run on a CT6x??

Yes.

Cheers
Sascha

[wongck]

[smilie=greencolorz4_pdt_12.gif]

[nativ]

Hi

Don't know if this has been mentioned .... another possible candidate ? Dodonpachi

http://www.youtube.com/watch?v=LBuKNb673SU

http://en.wikipedia.org/wiki/DoDonPachi

http://www.system16.com/hardware.php?id=803

http://wiki.arcadeotaku.com/w/DoDonPachi_SaiDaiOuJou

http://www.arcade-museum.com/game_detai ... me_id=7595

I think I had some more links but it either runs off the Cave 68000 or maybe I read somewhere about a 68020?