What spec Amiga to match the Gameboy Advance?

[eXeler0]

Saw this top 6 list of GBA racing games the other day and it made me wonder what spec Amiga it would take to run these games at similar framerates.
Some are basically SNES Mode 7 style games but there are a few that utilize a 3d engine..

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For most 2d games one would think that a vanilla 1200 could match it just fine, but when it comes to 3d or pseudo 3d, we need more power in the Amiga.

Now, the GBA has a resolution of 240x160 so it would be fair to compare to Amiga "chunky 1x2 mode".
The CPU in a GBA is a ~17Mhz ARM7TDMI with 32 kilobyte + 96 kilobyte (video) embedded RAM (which makes it fast)
+ 256 kilobyte "external" DRAM

Any guesses? What spec Amiga could run say "Need for Speed: Most wanted at 1x2 at a playable framerate? If I was to guess, I'd say at least an AGA+ (a fast) 040.

[rothers]

It is around about the 1200, I'd say the 1200 could run those 3D engines too in a SIMILAR way at that low resolution.

A mate of mine worked on the Duke3d GBA port and wow that engine used some wild optimisation, I suspect it's similar to the current 'Dread' doom game being made for the A500 by Altair.

The mode7 stuff, well, I've seen some interesting very fast ways of doing this on systems without the hardware.

I don't see anything in that video where if you told me it was on an A1200 that I'd be amazed, put it that way.

[eXeler0]

I'd actually be pretty impressed if I saw Need For Speed Most wanted run like that on a vanilla 1200 ;-) (I would probably guess I was looking at least at a 25MHz 040 if someone asked me)

[PortuguesePilot]

It's pretty hard to answer something like this, since both have custom hardware made specifically for them, and both have undocumented features. Although it might look unassuming, the GBA is actually quite a little champion.

As for the CPU, the GBA's main processor is a 16.8MHz RISC one (as opposed to the Amiga's, which is a 14MHz CISC) and is basically more similar to the Acorn Archimedes' one than to the Motorola 68EC020. The GBA's is full 32bit, while the 68EC020 only has a 24bit address bus. This makes the GBA's quite more powerful (in a raw 'bang the metal' kind of way).

In the RAM department, the Amiga has much more memory than the GBA but while the A1200 has 2MB slow chip RAM, the GBA has a total of 384kB (of which 96kB are used as instant VRAM internal to the rather good [for the time] CPU). The Amiga, as a computer, needs RAM space of OS features while the GBA, as a console, boots directly from ROM.

The A1200 also has lots of 16bit 'legacy' hardware constraints that limit it's full power (like keeping Paula unchanged, which meant no update to the sound and floppy disk drive density; the Blitter and the Copper still working at 16bit like it was in OCS' Agnus on a supposedly 32bit Alice, etc) while the GBA is a full-blown 32bit system built as so from the grounds up.

Graphically the GBA is both the GBC and the SNES direct heir, with a lot of shared features and even new ones. The GBC part of its inheritance gave the GBA a 'legacy' feature of treating every pixel on the screen as a 'sprite' (of-sorts... more technically savy guys can elaborate on this better than I can) the GBA graphic abilities are able to perform hardware tricks like the aforementioned "Mode 7" (which the Amiga can sort-of do via software tricks) and is capable of full 512 colours on-screen (as opposed of 256 on AGA) and the oh-so-important "chunky" feature that unfortunately both OCS and AGA lacked.

In the sound department, both are very able machines but the GBA has a dual DAC for sampling and is synth-capable using the CPU.

I guess an Amiga to be able to fully compete in the hardware department would need:
- Full 32bit CPU, including bus address (like, say, a 20MHz Motorolla 68030 but perhaps a 40 MHz 68040 accounting for what I predict as mandatory 'emulated features' of the GBA)
- Have at least 2MB of Fast RAM, 4MB of Fast RAM as recommended (for work/emulation clearance)
- Have chunky to planar abilities that AGA lacks, which means forcefully an RTG card.
- Some sort of 'sound card' that can had an extra DAC and synth abilities (I don't think it exists. Maybe a Prelude would work, I don't know).

As I said, it's hard to answer this question in definitive form.

[duga]

How about AGA + Akiko instead of RTG?

[PortuguesePilot]

Originally Posted by duga

How about AGA + Akiko instead of RTG?

For pure hardware? It's not enough, I'm afraid. Akiko is quite meagre in features, AFAIK.

Hardware-wise we'd need a sort of (IMO impossible) 'frankensteinian' Amiga to be able to replicate the GBA, hence why I think 'virtualisation' or emulation would have to be the way, thus the heavy recommendations on the CPU+RAM departments. The RTG has to be there because of AGA constraints (the chunky part and the 512 simultaneous colours part, plus other bits and bobs that are escaping me right now). To play GBA games 'as is' (or without compromises) an RTG is necessary. The sound department recommendations are perhaps the least necessary but for a full experience, the extra DAC and the synth-wave thing would be necessary as well.

[eXeler0]

Originally Posted by PortuguesePilot

For pure hardware? It's not enough, I'm afraid. Akiko is quite meagre in features, AFAIK.

Hardware-wise we'd need a sort of (IMO impossible) 'frankensteinian' Amiga to be able to replicate the GBA, hence why I think 'virtualisation' or emulation would have to be the way, thus the heavy recommendations on the CPU+RAM departments. The RTG has to be there because of AGA constraints (the chunky part and the 512 simultaneous colours part, plus other bits and bobs that are escaping me right now). To play GBA games 'as is' (or without compromises) an RTG is necessary. The sound department recommendations are perhaps the least necessary but for a full experience, the extra DAC and the synth-wave thing would be necessary as well.

Lets simplify this by not chasing a perfect 1 to 1 "feature port" between the two systems. Rather focus on the question, what Amiga it would take to run some of the more advanced GBA games Like Need For speed at a playable framerate so that the overall playing experience would be roughly equal.. never mind 8bit sound vs 16bit, or 512 colors vs 256-. Those things are of secondary importance in this context.

[PortuguesePilot]

Originally Posted by eXeler0

Lets simplify this by not chasing a perfect 1 to 1 "feature port" between the two systems. Rather focus on the question, what Amiga it would take to run some of the more advanced GBA games Like Need For speed at a playable framerate so that the overall playing experience would be roughly equal.. never mind 8bit sound vs 16bit, or 512 colors vs 256-. Those things are of secondary importance in this context.

That makes it all much simpler. I reckon a good 68030 @ 25MHz, 4MB of Fast RAM and a bunch of good software tricks (with AGA) would suffice.

[khph_re]

Yeah, I reckon 030 '25 running the same resolution as a GBA, but in less colours could possibly do it. You'd have nearly 4times the grunt of a base 1200. Flyin' high managed a good clip, and that was running at 320x256 on my 030 50.

The Amiga's bottleneck will always be the graphics subsystem for this sort of thing, and you may have to pre-scale some assets to make use of it's additional RAM, and make up for it's lack of scaling hardware.

[duga]

Originally Posted by PortuguesePilot

For pure hardware? It's not enough, I'm afraid. Akiko is quite meagre in features, AFAIK.

Hardware-wise we'd need a sort of (IMO impossible) 'frankensteinian' Amiga to be able to replicate the GBA, hence why I think 'virtualisation' or emulation would have to be the way, thus the heavy recommendations on the CPU+RAM departments. The RTG has to be there because of AGA constraints (the chunky part and the 512 simultaneous colours part, plus other bits and bobs that are escaping me right now). To play GBA games 'as is' (or without compromises) an RTG is necessary. The sound department recommendations are perhaps the least necessary but for a full experience, the extra DAC and the synth-wave thing would be necessary as well.

Instead of RTG. Of course with 020+ and fast mem.

[AmigaHope]

The low resolution 240x160 display actually is a blessing here, giving the Amiga much more leeway in dealing with the issues. Slow AGA bandwidth becomes less of an issue when you're only touch that small of a display.

CPU-wise an A1200 with even 1 meg of fast memory should have no trouble with competing with the GBA.

The big problem is that the sprite engine of the GBA is vastly better than AGA's, and it includes a tile mode for fast screen drawing. The blitter can be used to effectively create a tilemap, but if it spends most of its time doing that, you mostly lose the ability for blitter objects and are mostly limited to the Amiga's anemic hardware sprites.

Not only does the GBA have more hardware sprites, it can rotate and scale them which is completely out of the abilities of the Amiga custom chipset. This means you're stuck doing sprites entirely with the CPU.

Thus if you want an Amiga capable of competing with a GBA, it would need to be an A1200 with 2M chip + 1M fast plus some sort of ROM adapter (the GBA uses cartridges so it's kind of cheating). If you didn't have some sort of cartridge slot, you'd have to have at least 8M of fast RAM to even compare -- this is assuming you are using level loading and such from a hard drive. If you wanted to run entirely from memory like a GBA cart, you'd need 32M of fast RAM (which is the largest GBA carts ever became). Most importantly you'd need at least a 68040 or maybe a 68060 to drive the sprite engine in software since the AGA chipset cannot do this in hardware. 128 rotated+scaled sprites is nothing to sneeze at.

EDIT: The A1200 is much closer in capability to the Gameboy Color. While it completely outclasses it in some areas (display quality, processing power, sound quality), you'd have to dedicate resources to match the Gameboy Color's tilemap and sprite abilities. The GBC has sprites that are similar to OCS sprites, but it has 10 per line vs OCS/AGA's 8 per line, which means the CPU and blitter have to pick up the slack for the extra 2 sprites. The blitter is busy with building the tilemaps, so the CPU will have to draw the two extra sprites as well as do collision calculations with the other 8 hardware sprites. It should be able to do this no problem but it will be pushing its abilities, thus an A500 probably could not do 1:1 an advanced GBC game, while the A1200 could, even though both of them could do some kinds of simulation games that the GBC could never hope to do.

So in terms of running games that take advantage of all the gameboy strengths:

A500 < GBC < A1200 < GBA < Hella expanded A1200

Running games with Amiga strengths:

GBC < A500 < GBA < A1200 < Hella expanded A1200

[khph_re]

A good answer, but bear in mind consoles use megabits to quote storage, not megabytes. So the biggest GBA cart is 4MB.

An A1200 with fast ram is vastly faster than the Z80/8080 derivative in the GB color. And i'm not sure it would be necessary to use tilemaps when you have a true bitmap display.

[hitchhikr]

so the biggest gba cart is 4mb.

32 megabytes.

[khph_re]

I'm no expert on GBA, so I'll bow to tour greater knowledge. i never developed for it, thats pretty big. Was it final fantasy or something like that?
Anyway, we wouldn't need it all in memory at the same time.

[eXeler0]

Originally Posted by khph_re

Yeah, I reckon 030 '25 running the same resolution as a GBA, but in less colours could possibly do it. You'd have nearly 4times the grunt of a base 1200. Flyin' high managed a good clip, and that was running at 320x256 on my 030 50.

The Amiga's bottleneck will always be the graphics subsystem for this sort of thing, and you may have to pre-scale some assets to make use of it's additional RAM, and make up for it's lack of scaling hardware.

I really don't see a 25MHz 030 AGA Amiga run something like Vrally3 as well as the GBA does.

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[Daedalus]

Originally Posted by PortuguesePilot

The GBA's is full 32bit, while the 68EC020 only has a 24bit address bus. This makes the GBA's quite more powerful (in a raw 'bang the metal' kind of way).

How, exactly, does having more address bits make a machine like the GBA more powerful? You can't bang any metal that's not there, and the GBA doesn't have more than 16MB of addressed hardware, so there's no metal there to bang in this case. In theory, this could be used to map the 32MB cartridges directly without needing to page, but in reality the 32-bit address bus wasn't used in this way and so cartridges were paged much like most other consoles, including the SNES.

The A1200 also has lots of 16bit 'legacy' hardware constraints that limit it's full power (like keeping Paula unchanged, which meant no update to the sound and floppy disk drive density; the Blitter and the Copper still working at 16bit like it was in OCS' Agnus on a supposedly 32bit Alice, etc) while the GBA is a full-blown 32bit system built as so from the grounds up.

There may be some merit here regarding the blitter, but again, you're equating far too much with numbers of bits on various buses. Keeping Paula unchanged has nothing to do with being 16-bit, for example. After all, it manages to have four 8-bit channels, which you can play together for 32 bits of audio goodness. Right? In reality, for the vast majority of audio tasks, 16 bits is perfectly fine. Having Paula on a fully 32-bit bus certainly isn't going to improve floppy access speed, nor will it improve the analogue controller responsiveness, interrupt speed or the audio quality. All that might improve is the data throughput, and for audio, that's not really a huge deal when you're only talking KB/s of data.

- Full 32bit CPU, including bus address (like, say, a 20MHz Motorolla 68030 but perhaps a 40 MHz 68040 accounting for what I predict as mandatory 'emulated features' of the GBA)

See above regarding address bus width. A 68030 should be able to do the job just fine so long as you're allowing features to be translated to Amiga hardware and not totally emulated in software.

- Some sort of 'sound card' that can had an extra DAC and synth abilities (I don't think it exists. Maybe a Prelude would work, I don't know).

Funny that you mention a Prelude, since the A1200 version of that card attaches to the system through an 8-bit bus

[frank_b]

It's been awhile since I've programmed one but the GBAs sprite and playfield hardware is amazing for 2d. 128 sprites up to 64 pixels tall and wide. 32 custom rotation and zoom levels which can be assigned per sprite. 256 colours (one transparent) or 16 palettes of 16. 4 playfields with zooming on two of them. 15 bit Paulette. Separate pallets for sprites and playfields. 16 16 colour tiles or 256 colours per playfield. Can feely mix and match 16 colour modes with 256 ones. Additive blending per sprite. Wrap around tile mapped scrolling which the programer can set the orientation per page. ie 2 high or 2 wide. The Amiga ins't in the same league for 2d IMHO.

[khph_re]

Originally Posted by eXeler0

I really don't see a 25MHz 030 AGA Amiga run something like Vrally3 as well as the GBA does.

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At no point did i say 'as well as' i specifically said in less colours for starters. The car is is just a sprite, the trees we would have to pre-scale. That just leaves the landscape.

[roondar]

Originally Posted by AmigaHope

EDIT: The A1200 is much closer in capability to the Gameboy Color. While it completely outclasses it in some areas (display quality, processing power, sound quality), you'd have to dedicate resources to match the Gameboy Color's tilemap and sprite abilities. The GBC has sprites that are similar to OCS sprites, but it has 10 per line vs OCS/AGA's 8 per line, which means the CPU and blitter have to pick up the slack for the extra 2 sprites. The blitter is busy with building the tilemaps, so the CPU will have to draw the two extra sprites as well as do collision calculations with the other 8 hardware sprites. It should be able to do this no problem but it will be pushing its abilities, thus an A500 probably could not do 1:1 an advanced GBC game, while the A1200 could, even though both of them could do some kinds of simulation games that the GBC could never hope to do.

I've never seen even a single GBC game that I felt couldn't be done on an A500 though. Perhaps there exists an example somewhere, but the best games I personally saw were rather underwhelming compared to even mid-tier games on the Amiga (obviously only speaking from a technical level here, I'm not saying there were no fun games on the GBC ).

In fact, the most impressive GBC game I can personally remember was Super Mario Brothers. And that is certainly something on the level of what the A500 can do.

[eXeler0]

Originally Posted by khph_re

At no point did i say 'as well as' i specifically said in less colours for starters. The car is is just a sprite, the trees we would have to pre-scale. That just leaves the landscape.

Well, the topic here is "what spec Amiga can match a GBA" so if you're telling me a 25MHz 030 could not do it as well, then we simply need to up the spec, don't we? ;-) Why not suggest a 50MHz 030 or 25MHz 040.