Arcade / Console --> Amiga conversion discussions

[dlfrsilver]

Originally Posted by Retro-Nerd

Crazy Cars 3 was barely average. What a boring game. Reminds me of 8bit games, especially gameplay-wise/physics.

Richard Hooper, the english engineer who did the game did a great programming. Crazy Cars III physics are what i would have loved to see on the Lotus series.

[trydowave]

can more ram be accessed quickly from the Amiga expansion port as mentioned in this old thread?
http://www.amiga.org/forums/archive/...p/t-22715.html

[zero]

Can't have more chip RAM. The custom chips just can't address it. Expansion port RAM isn't very fast.

[TuRRIcaNEd]

@trydowave - Why do you ask?

[trydowave]

it seems that the ST has come out on top regarding chip ram. so in theory it seems like it can beat the amiga in terms of arcade ports.

i was just wondering if there was any kind of trickery that would allow the amiga to pull off the same or nearly the same results. i know it has a limitation of 1 to 2mb chip ram so i was thinking about otther ways to deal with problem be it running from a cartridge, hdd, loading during gameplay (like salves curve did), compression of sprite data or reprogramming the game to fit into 2mb (im not sure but i think ghouls n ghosts has all sprite data ready to access at any time) the arcade rom is 2mb and it takes 16mb to run on pc.

theres some real quality releases on the c64 (sams journey) and the ste version of ghouls n ghosts and the demo of final fight really impressed me. i really would like to see the amiga being pushed to its limits again (thinking of lionheart on ecs) but unfortunately either no one knows how or simply cant be bothered.

[Galahad/FLT]

Originally Posted by trydowave

it seems that the ST has come out on top regarding chip ram. so in theory it seems like it can beat the amiga in terms of arcade ports.

i was just wondering if there was any kind of trickery that would allow the amiga to pull off the same or nearly the same results. i know it has a limitation of 1 to 2mb chip ram so i was thinking about otther ways to deal with problem be it running from a cartridge, hdd, loading during gameplay (like salves curve did), compression of sprite data or reprogramming the game to fit into 2mb (im not sure but i think ghouls n ghosts has all sprite data ready to access at any time) the arcade rom is 2mb and it takes 16mb to run on pc.

theres some real quality releases on the c64 (sams journey) and the ste version of ghouls n ghosts and the demo of final fight really impressed me. i really would like to see the amiga being pushed to its limits again (thinking of lionheart on ecs) but unfortunately either no one knows how or simply cant be bothered.

The ST having more chip ram isn't much of an advantage, the only thing it does is save a transfer/copy of data stored in slow ram like most A500's have got, but thats not really much of an issue if you design your game properly.

[zero]

It's only an issue in arcade ports where you have a massive ROM, but in that sense it's no different than when you would have had to design for floppy disk and 512k/1 meg back in the day because upgraded systems were rare.

[Tigerskunk]

I think it's kind of sad, that the Amiga doesn't have a proper cartridge port.

It's a nice format to sell games on and doesn't have the problems of disks.
Plus it's super collectible

Maybe someone could design some freaky wide sideport cartridge...

[zero]

Carts are good if the system is designed for them, but the Amiga designers decided to have a lot of RAM instead.

At that time most games oriented machines had very little RAM but made up for it with ROM carts. Most general purpose machines had a lot of RAM but slow storage systems.

Some games are just impossible to do on machines with very little RAM. Often cartridges for consoles had to have their own extra on-board RAM or cut the game right down to fit. Like Sim City on the NES, which was likely cancelled because the extra RAM in the cart made it unprofitable.

[ross]

Nothing prevents you from creating a "cartridge" for A600 or A1200 in PC Card format.
In Kickstart ROM there is code that supports autoboot and you can have a fast enough access (exclusively 16-bit memory).
You can also create mixed ROM/EPROM/SRAM systems with bankwitching.
Why was it never done? Costs too much...

[trydowave]

Originally Posted by ross

Nothing prevents you from creating a "cartridge" for A600 or A1200 in PC Card format.
In Kickstart ROM there is code that supports autoboot and you can have a fast enough access (exclusively 16-bit memory).
You can also create mixed ROM/EPROM/SRAM systems with bankwitching.
Why was it never done? Costs too much...

this is interesting. could a large rom game be accessed from the pcmcia slot as quick as the ste 4mb ram.
would it be quick enough to access data when needed?

[ross]

Originally Posted by trydowave

this is interesting. could a large rom game be accessed from the pcmcia slot as quick as the ste 4mb ram.
would it be quick enough to access data when needed?

I can be wrong but I seem to remember that Gayle's cycles are CCK/2 then 563.87ns which correspond to 3.5MB/s.
This is logically a theoretical speed but I would say that 2.5MB can be reached up. Not an exceptional speed but not too slow, considering it a "cartridge space".
Sure fast like or better than the internal IDE HDD.
I have no idea what speed has the STe memory but certainly faster than this...

EDIT: ok found this in SAKURA site:
On Amiga 600 Gayle chip is configured for 570ns access time by default,
which results in performance similar to Fast RAM expansions attached on
top of 68000 CPU.
On Amiga 1200 the default configuration is 250ns access time, but Kickstart
automatically reconfigures Gayle for 100ns access, according to CIS.
This results in some performance increase compared to an unexpanded
Amiga 1200. Contrary to popular opinions, Amiga 1200 equipped with
high performance, correclty configured PCMCIA SRAM expansion (like
this one) is performing better than Chip RAM only system.

[frank_b]

Originally Posted by ross

Sure fast like or better than the internal IDE HDD.
I have no idea what speed has the STe memory but certainly faster than this...

Ste memory speed is 4 mb a second. You might as well stream from fast RAM to chip RAM instead. The blitter on the Amiga can't access the PCMCIA RAM.

The current port of Ghouls and Ghosts works on a 2 meg STe. It might be possible to get it running on a 2 meg ECS machine.

[TuRRIcaNEd]

Originally Posted by trydowave

it seems that the ST has come out on top regarding chip ram. so in theory it seems like it can beat the amiga in terms of arcade ports.

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...

[ovale]

Originally Posted by TuRRIcaNEd

Even a resource-heavy coin-op like OutRun's ROM data is just shy of 2MB in it's entirety.

Just for sake of completeness I would add that arcade hardware has plenty of ways to amplify the effect of such costly ROMs. For example, h and v flip, zoom, tiles even for sprites, hundreds of palettes. This means that on the home computers you have to emulate such hardware making things slower or duplicate gfx assets using N times more RAM.

[frank_b]

Originally Posted by TuRRIcaNEd

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.

*** - 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...

ECS can address 2 meg of chip ram.

BTW it doesn't really matter if you have a 16 bit CPU bus (The video fetches are 32 bit) at 16 mhz or a 32 bit chip ram bus at 7 mhz. It's about the same speed for 32 bit access on both. 16 bit access will be quicker on the Falcon. There's no datacaching of chip ram on the Amiga either. Swings and roundabouts. Just use fast ram for CPU accesses on both architectures.

[Shatterhand]

You know, regarding driving games engines.....

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, it has music and sfx playing together and it was actually ported from the Atari ST which means there's probably some optmizing to be done there (Pretty sure the "Distance" and "Speed" text over the main screen is taking blitter/cpu time that could be used if it was done in a i different way)

Isn't something good there to check out?

[zero]

I've been looking for a demo where they had a road effect running in 1 frame (50 fps). I can't remember its name now, just the road effect using a copperlist to select pre-rendered road bitmaps.

Of course that technique was extended in other demos to do not just the road but a kind of tunnel effect. IIRC Arte or one of the other Sanity demos started that way. It's definitely the way to go for a high performance road effect if you can live with DPF.

[zero]

Ah, it was Arte:

[ Show youtube player ]

[Tigerskunk]

Originally Posted by zero

just the road effect using a copperlist to select pre-rendered road bitmaps.

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