Arcade / Console --> Amiga conversion discussions

[TuRRIcaNEd]

Originally Posted by ovale

Just for sake of completeness I would add that arcade hardware has plenty of ways to amplify the effect of such costly ROMs.

Agreed, but the computers usually had considerably more work RAM to play with by the standards of the time. You only have to load in the data for a subset of stages at any one time too.

Originally Posted by frank_b

ECS can address 2 meg of chip ram.

Ah yes - I was thinking of the "Fatter" Agnus that appeared on the Rev6a A500 et al. Forgive me, it was very late and I was exhausted!

Swings and roundabouts. Just use fast ram for CPU accesses on both architectures.

That was kind-of what I was getting at. Generally if you have a good idea of the pros and cons of the architecture on which you're working, you can come up with optimised routines which render the on-paper specs less important.

Originally Posted by Shatterhand

Batman on Amiga, 1989 game, that driving level runs at a very reasonable framerate, has lots of ontrack objects, parallax background, hills, smoke effects on the car...

Well, the background isn't parallax, and there's a big status bar at the bottom of the screen (approx 60px high) which means you don't have to draw as much vertically in terms of the road routine (Outrun Europa uses the same trick). The music is only using 3 channels, freeing the 4th up for SFX. It was a very good routine for 1989 though.

[trydowave]

i was playing the megadrive port of ghouls n ghosts today and although the colours have been toned down and some animation frames have been dropped its a very good conversion.

am i guessing right when i say that its nothing the Amiga couldn't handle?

[dlfrsilver]

Originally Posted by TuRRIcaNEd

Um... With respect, I think you might be getting some wires a little crossed. The ST does not have "Chip RAM" as such because its original incarnation had no dedicated DMA-based graphic or sound hardware. Like the original incarnation of the PC, just about everything had to be done in software via the CPU. The STE does have a "BLiTTER", which is tied into the main memory architecture and as such can in theory use any part of the RAM in the machine if I understand things correctly.

Coin-ops and cartridge-based consoles of that era work on a very different principle to home computers in some ways. Because the data is stored on ROM chips from which data can be accessed much faster than floppy or even hard disk, the implementation of most games is constantly streaming data from those ROMs to what is usually a surprisingly small amount of work RAM (for example the Sega Mega Drive had 72kb - yes, *kb* - of work RAM and 64kb of video RAM)**. With a computer, you'd be trying to get as much of the game data as possible into RAM to avoid loading from disk wherever possible.

When we talk about Chip RAM in the Amiga we're referring to the RAM that is directly addressable (i.e. without needing a constant feed from the CPU) by the custom chipset. This was hard-limited by the architecture of the Agnus/Alice chips - at 512K (OCS), 1MB (ECS) and 2MB (AGA). By the standards of arcade games of the era that's actually quite a lot. Even a resource-heavy coin-op like OutRun's ROM data is just shy of 2MB in it's entirety.

As Galahad says, if you have expansion RAM it's not that big a deal to swap data in and out of Chip RAM as required - in fact, to do so is effectively using the same technique as the consoles. On an AGA machine, Fast RAM is hooked up via a full-width 32-bit bus*** - which gives the programmer even more latitude to come up with efficient memory-management techniques.

** - One of the reasons quite a few developers found the PS2 a pain to work with was because it was still using the same techniques (albeit constantly streaming from an optical disk rather than ROM).

*** - The lack of a 32-bit bus was the Falcon's Achilles' Heel. All that fancy hardware, unable to communicate as efficiently as it needed to...

coin-op machines only uses 64kb for tiles metadata. that's why it's so low compared to the Amiga. The Amiga has the graphics and tiles metadata in RAM.

The tiles metadatas are sent to the 64kb of ram on the coin-op by the 68000 processor. The graphics chips then automatically display the corresponding tiles by looking this specific ram content.

[Galahad/FLT]

Originally Posted by trydowave

i was playing the megadrive port of ghouls n ghosts today and although the colours have been toned down and some animation frames have been dropped its a very good conversion.

am i guessing right when i say that its nothing the Amiga couldn't handle?

Other than dropping the parallax, theres no reason why the Amiga couldnt have done it.

Several issues, one it was released by US Gold who were particularly relaxed about what was acceptable, secondly the programmer David Broadhurst was still learning to get to grips with the Amiga, you only have to look at Dojo Dan and Assassin to see how he improved and doubtless would have turned out a better version later in his career, and lastly, the Atari ST.

Other than the music, there is nothing Amiga about the conversion, 16 colour graphics, massive scoreboard, jerky scrolling, all the things that make an ST owner squeal with delight!

[DamienD]

Originally Posted by Galahad/FLT

Other than the music, there is nothing Amiga about the conversion, 16 colour graphics, massive scoreboard, jerky scrolling, all the things that make an ST owner squeal with delight!

ROFL

...now where's our resident "Atari ST / Amiga sucks" member kovacm, who loves trashing anything Amiga plus documenting EAB members' comments on his website?

He'd have an absolute field day with your post Sir Galahad.

Oh that's right, I banned him... Shame really (not)

[OmegaMax]

Originally Posted by Galahad/FLT

Other than the music, there is nothing Amiga about the conversion, 16 colour graphics, massive scoreboard, jerky scrolling, all the things that make an ST owner squeal with delight!

[Shatterhand]

Originally Posted by TuRRIcaNEd

Well, the background isn't parallax, and there's a big status bar at the bottom of the screen (approx 60px high) which means you don't have to draw as much vertically in terms of the road routine (Outrun Europa uses the same trick). The music is only using 3 channels, freeing the 4th up for SFX. It was a very good routine for 1989 though.

Just checked on youtube, the background has buildings and then "shadow" buildings behind scrolling at a different speed of the buildings in front. For me thats "Parallax"

And yeah, ther's a big status bar at bottom of the screen but, like I said, it came from Atari ST, sure there's room to improve it on an Amiga

[zero]

Originally Posted by Steril707

Can you explain that a bit more.. ?
I think I don't get it yet how that was done...

Some info here: http://www.extentofthejam.com/pseudo/

Basically you can pre-render the road graphics, the kind of triangle thing you see on that site. Then for every scanline of the screen you can select a line from that "texture" and shift it left/right and alternate the colours to make it look like it is moving.

I came up with an even better way, which I want to try to test over the new year but probably won't get time. You can use just the copper and sprites for a zero bitplane version.

[saimon69]

@TurricanED
If you want to have more bandwidth i dare to advice that you should consider coding the outrun port directly in 200px and treat it like dynablaster on PAL machines forcing the NTSC resolution (plus that would give you the advantage of working in US machines too)

[saimon69]

Originally Posted by zero

Some info here: http://www.extentofthejam.com/pseudo/

Basically you can pre-render the road graphics, the kind of triangle thing you see on that site. Then for every scanline of the screen you can select a line from that "texture" and shift it left/right and alternate the colours to make it look like it is moving.

I came up with an even better way, which I want to try to test over the new year but probably won't get time. You can use just the copper and sprites for a zero bitplane version.

I think is the same way Mr.Nutz 3D level work, if am correct?

[zero]

I don't know, I never played Mr. Nutz :-)

[chb]

Originally Posted by saimon69

I think is the same way Mr.Nutz 3D level work, if am correct?

Only partially, Mr. Nutz uses a similar technique but shrinks the lines in horizontal direction by changing the scroll register values several times per raster line (a line can be shrunken by max. 16 pixels with this technique, so you need several pre-scaled images if you need more steps). This effect was first used by Chaos/Sanity, who wrote the 3d parts for Mr. Nutz. Watch e.g. World of Commodore (were you can even spot a very similar texture ) or Optimum Fuckup by Sanity for an extensive usage of that effect. I think (not sure 100%) arte just uses pre-scaled lines, maybe even pre-scaled tiles because the texture looks very repetitive.

[saimon69]

@chb
With that technique makes me think a street passages should not be that dramatic nor memory consuming, since is just curbs and dashed lines - could be done in one, max two bitplanes - however IANAC

[chb]

Well, there's a problem with roads - they are not necessarily centered on the screen, so you need to scroll, but then you can't use the scroll register anymore to shrink the line, so you need 16 pre-shifted graphics or use the blitter to shift it. If you look at Mr. Nutz/the Sanity demos, it's always center perspective without left/right movement. I'm therefore quite sure arte does not use this trick - the floor is bent.

[Shatterhand]

Originally Posted by Galahad/FLT

Other than dropping the parallax, theres no reason why the Amiga couldnt have done it.

Several issues, one it was released by US Gold who were particularly relaxed about what was acceptable, secondly the programmer David Broadhurst was still learning to get to grips with the Amiga, you only have to look at Dojo Dan and Assassin to see how he improved and doubtless would have turned out a better version later in his career, and lastly, the Atari ST.

Other than the music, there is nothing Amiga about the conversion, 16 colour graphics, massive scoreboard, jerky scrolling, all the things that make an ST owner squeal with delight!

Bionic Commando was made by him and IMO was even worse than G'nG . I was really surprised to notice Assassin was made by him, since Assassin is very slick, smooth and well done.

[TuRRIcaNEd]

Originally Posted by Shatterhand

Bionic Commando was made by him and IMO was even worse than G'nG . I was really surprised to notice Assassin was made by him, since Assassin is very slick, smooth and well done.

This just proves the point that Galahad was making (I've said similar before)... Publishers in the early days didn't really give their developers time to learn the Amiga properly - they just wanted something out the door as quickly and cheaply as possible.

The issue in this case was not that David Broadhurst lacked talent when it came to code-wrangling, simply that he was never given the proper time to get to grips with the platform at first.

[trydowave]

Originally Posted by Shatterhand

Bionic Commando was made by him and IMO was even worse than G'nG . I was really surprised to notice Assassin was made by him, since Assassin is very slick, smooth and well done.

Bionic Commando was a travesty on the Amiga. You know a game is bad when the scrolling itself hinders a major part of the gameplay.

[OmegaMax]

Originally Posted by TuRRIcaNEd

This just proves the point that Galahad was making (I've said similar before)... Publishers in the early days didn't really give their developers time to learn the Amiga properly - they just wanted something out the door as quickly and cheaply as possible.

The issue in this case was not that David Broadhurst lacked talent when it came to code-wrangling, simply that he was never given the proper time to get to grips with the platform at first.

Your making it sound like only amiga programmers weren't given enough time to learn the hardware,console programmers had to learn the hardware as they programmed it also.
I'll quote Chris Shrigley "

• Ex-Mutants (Sega Genesis) Project Archive – First game I programmed in the US for ACME Interactive They became Malibu Interactive, before the game was released. This was the game I learned the Genesis system and the 68000 programming language on! I have some wonderful (and crazy) memories making this game!
• Cliff Hanger (Sega Genesis) Project Archive – Second game I wrote for Malibu Interactive, based on the dubious movie by the same name.

[mcgeezer]

Originally Posted by OmegaMax

Your making it sound like only amiga programmers weren't given enough time to learn the hardware,console programmers had to learn the hardware as they programmed it also.
I'll quote Chris Shrigley "

• Ex-Mutants (Sega Genesis) Project Archive – First game I programmed in the US for ACME Interactive They became Malibu Interactive, before the game was released. This was the game I learned the Genesis system and the 68000 programming language on! I have some wonderful (and crazy) memories making this game!
• Cliff Hanger (Sega Genesis) Project Archive – Second game I wrote for Malibu Interactive, based on the dubious movie by the same name.

You're comparing Apples with Oranges.

At the time the ST was the biggest rival to the Amiga as lots of games were coded on the ST first because it was more established as a games machine given it had the luxury of more time on the shelves.

When the Amiga got traction software houses just did the ports of ST games cos they could get them out of the way in a matter of weeks, in reality all they had to deal with was the bitplane, sound, input and floppy differences - everything else was pretty much the same. The slightly faster CPU in the ST was probably negligible and perhaps is the reason that the odd port is more shit on the Amiga than it was on the ST.

[OmegaMax]

I don't think anyone is debating that the amiga got ST ports,I'd disagree with that amiga got the odd sh*t port part though as majority of them were quite terrible for amiga standards,but that is personal opinion.