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Old 19 June 2002, 19:00   #1
dreamkatcha
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AGA Vs non-AGA games

I'm sure this must have been asked a million times before, but since there's a 4 character minimum limit on the search engine I can't find the relevent posts.

Anyway, my question is, what's the difference between an AGA game and a non-AGA game apart from the obvious, that they can only be played on an Amiga which has the AGA chipset built-in? Is it just that they have better graphics or is there something else I've not considered?
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Old 19 June 2002, 19:50   #2
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The AGA and ECS or OCS chipsets are very different.

Teh AGA chipset has a greater palette and can allocate more colors on screen at once than previous chipsets, and it has lots more display modes too..

So the main difference betwen an AGA game and an ECS/OCS game, is that you will, at least, see more colors.

Also teh blitter speed is different, so some stuff goes faster. And hardware sprites can be bigger.

And since A1200s come with 2MB Chip de-facto, games can have more graphic and sound information.

Hope that helps!
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Old 20 June 2002, 00:18   #3
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With some exceptions, AGA games are 256 colors and ECS ones are 32 which makes a HUGE difference.
 
Old 20 June 2002, 00:34   #4
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Floppy disk

ok ....if there is only a 256 color pallette how is it possible to display 16million colors at once on the screen?....or is this missinformation that I have read.....just curious ........peace
 
Old 20 June 2002, 00:36   #5
Ian
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Some games have difference that you may not even notice, one such game is:-

Fantasy Flyer

If you play the game in AGA mode you get extra big sprites scrolling along in the foreground quite nicely thanks to the A1200's extra power, but if you run the game in ECS mode the sprites aren't there.

Try it with WinUAE and see if you can spot the difference
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Old 20 June 2002, 00:39   #6
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Quote:
Originally posted by ToTalXS
ok ....if there is only a 256 color pallette how is it possible to display 16million colors at once on the screen?....or is this missinformation that I have read.....just curious ........peace
HAM-8 mode (Or at least I think that's what it was called)

Much like the A500 had HAM mode for 4096 colours on the screen the A1200 had HAM-8

Virtually useless for anything other than DPaint V and other apps of the same ilk, but great for showing off your Amiga with.

There was an A500 game that actually used HAM mode, I can't remember what it's called now, but it was just a series of pictures that you clicked on to progress the story, crap, but great for showing off to your ST owning mates back in the day
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Old 20 June 2002, 01:14   #7
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Ian is basically right about Ham-8 mode, it allows you to display 262144 (out of a palette of 16777216 colours) different colours on screen at once.

It worked by employing a hardware trick where the colour registers were altered slightly in each pixel to the one next to it, this theoretically allowed all these colours, but it was useless for anything other than still pictures due to mainly to the amount of power required to shift the screens quickly (each pixel had to be updated individually) also because each pixel register is changed slightly if there was high conrast between the two colours you would get banding (makes a mess).

Other advantages of the AGA chipsets are as others have said higher resolutions, bigger sprites (upto 64 pixels wide and as tall as memory permits) the ability to display more sprites on screen at once, moving gfx memory around quicker.

Hope this is helpful
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Old 20 June 2002, 01:20   #8
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thanks....I also read somewhere that there is no monitor made that can display all the pixels you could display in hamm8 mode...is this also correct......also the A1000 had a ham mode as well right?.....
 
Old 20 June 2002, 01:22   #9
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Hmmmmm....

Right, some facts:

1). The blitter is the same speed in the A12oo as the A5oo

2). 16.8 million colours, max 256,000 on screen through HAM-8, which is pointless as it takes up too much DMA time to be anything more useful than static pictures

3). Sound channels are clearer, and if you remove one of the sound leads from its socket, all channels will be played through the other connected socket.

4). 14Mhz processor with caches which means processor run games are quicker.

5). Greater display modes

6). 2 Meg of chip ram which is useful obviously.

7). Bigger sprites (64 pixels wide) and Overscan bug is fixed where you would lose sprite 7

whilst one of you is correct in saying ECS 32 colours AGA 256, the fact is most A5oo games used a lot more than that via the copper. With the exceptions of muppets like Tiertex, Kremlin, Teque, most games were inexcess of 200 colours, simply do a screen grab with WinUAE and then get your favourite paint package to count the colours.

Oh yeah, you could also quarter pixel scroll on the A12oo whereas the A5oo would scroll pixel size, and the copper could reload the screen quicker on the A12oo (4 pixels as opposed to 8pixels on the A5oo)
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Old 20 June 2002, 01:39   #10
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Quote:
I also read somewhere that there is no monitor made that can display all the pixels you could display in hamm8 mode...is this also correct
No to display 262144 colours a display that allows more than the above number of pixels to be displayed on screen can show more for example on PC 640x480 = a possible 307200 different colours at once (each pixel is different)

On an Amiga Hi-Res Lace (640x512) can display 327680 pixels so in theory it is possible, whether the Amiga's actual limitations hindered this I am not sure (Every pixel being different)

@Galahad : How many different colours (in theory) can an AGA amiga display using the copper in it's highest resolution?
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Old 20 June 2002, 01:45   #11
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Oh god!

163840 I think!

but that would be one fucking enormous copper list!
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Old 20 June 2002, 05:22   #12
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Re: Hmmmmm....

Quote:
Originally posted by Galahad/FLT
1). The blitter is the same speed in the A12oo as the A5oo
I always read it had a faster blitter. Damned magazine liars! Thanks for clearing it up!

Quote:
3). Sound channels are clearer, and if you remove one of the sound leads from its socket, all channels will be played through the other connected socket.
The A600 does the "remove one lead and we get mono" thing, too.

Quote:
whilst one of you is correct in saying ECS 32 colours AGA 256, the fact is most A5oo games used a lot more than that via the copper.
I think they meant that the games would use the 32 color mode and on AGA, the 256 color mode. which I dont think it ever happened either, they used the copper for the colors and stuff, but generally they would use a 16 colro screen on the A500, and a 64 color screen on the AGA machine. Please correct me if I'm wrong, I think the 256 mode was too slow for games (look at Simcity :P)
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Old 20 June 2002, 09:58   #13
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Quote:
whilst one of you is correct in saying ECS 32 colours AGA 256, the fact is most A5oo games used a lot more than that via the copper.
Yes there are exceptions, actually their numbers are too many to count as exceptions I think.
 
Old 20 June 2002, 10:59   #14
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Quote:
copper could reload the screen quicker on the A12oo (4 pixels as opposed to 8pixels on the A5oo)
A1200's copper is exactly as fast (or slow..) as A500's. It may look faster because AGA bitplane DMA usually is set to use high bandwidth fetch modes that leaves more DMA time to copper and blitter, but I think you must already know this

Quote:
16.8 million colours, max 256,000 on screen through HAM-8, which is pointless as it takes up too much DMA time to be anything more useful than static pictures
I agree that HAM8 is not useful for moving screens but I don't believe on your DMA-time explanation because AGA 8 bitplane lores screen with FMODE-register set to 3 uses only 1/4th of available DMA time..
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Old 20 June 2002, 12:57   #15
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Now that's what I call a comprehensive answer! Thanks everyone. You really know your stuff.

What it was - I've got a real Amiga 1200 and I've already got all my fave classic games in ADF format, but I started wondering if it was worth my while getting the AGA versions instead wherever possible. You've now convinced me it's worth searching a bit harder to track them down. There's no need to settle for second best when everything is free.
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Old 20 June 2002, 19:18   #16
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Hmmm

I agree that HAM8 is not useful for moving screens but I don't believe on your DMA-time explanation because AGA 8 bitplane lores screen with FMODE-register set to 3 uses only 1/4th of available DMA time..
;-----------------------------

Lo Res AGA 8 bitplane is nice, but if you want high quality output, you would go for Hi res, hence my statement. If you want to output the highest quality, it then becomes pointless trying to shift it around, and then the blitter has 3 extra bitplanes to shift around... etc, etc. Sometimes Commodore could be quite inventive, and other times they were idiots!!!! Most of the A12oo design is because of idiots!
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Old 21 June 2002, 17:22   #17
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Re: Hmmm

Quote:
Originally posted by Galahad/FLT
I agree that HAM8 is not useful for moving screens but I don't believe on your DMA-time explanation because AGA 8 bitplane lores screen with FMODE-register set to 3 uses only 1/4th of available DMA time..
;-----------------------------

Lo Res AGA 8 bitplane is nice, but if you want high quality output, you would go for Hi res, hence my statement. If you want to output the highest quality, it then becomes pointless trying to shift it around, and then the blitter has 3 extra bitplanes to shift around... etc, etc. Sometimes Commodore could be quite inventive, and other times they were idiots!!!! Most of the A12oo design is because of idiots!
From what I recall of the magazine's etc. following CBM's demise AGA design had more to do with cost-cutting from management than anything else.
Rather than invest sufficient time & resources into the AAA design, the AGA design was rushed onto the market,whilst plans for a next-gen RISC based Amiga were mooted but never saw the light of day.
The AGA machines never lived up to the hype that the AAA design specs probably would've delivered.
More to the point, they certainly lacked the technical wizardry that the original Amiga had when it was launched.
As was noted earlier, whilst the AGA machines could display 256 colours, the programmers of 3D games particularly complained the Amiga couldn't handle 256 colour 3D games as the Amiga lacked a byte-per-pixel mode ala the PC's display. Indeed early plans by Bullfrog for a 256 colour hi-res version of Syndicate were dropped because of this.
I could be wrong,but I thought that the Amiga version of Links (The PC Golf game), might've used the HAM mode,("Hold-And-Modify"),. I believe as a result it was incredibly slow, but that it did use it. And what about all those digitised Strip Poker type games,didn't they use the HAM mode?
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Old 21 June 2002, 18:41   #18
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Correct

Links and Strip Poker aren't exactly pushing the hardware though! Strip Poker has a static screen with a sprite pointer and only has to redraw the card decks, which it doesn't have to be frame critical, it doesn't have to be smooth, and its a VERY simple piece of code that wouldn't trouble even the most feeble hardware.

Links drew the screen and then moved a tiny ball around, so the programmer only had to refresh the areas that the ball moved in, and well, try and do Lionheart in HAM mode and then try and shift it......... HAM mode is fine for static non-action games, anything more than that and its utterly pointless, but clever use of copper means a very colourful game.

I think if memory serves me right, Jim Power is Dual Playfield, so technically, its only a 16 colour game, but with clever copper usage, its too damned colourful!!
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Old 21 June 2002, 19:45   #19
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Wink

Galahad,I wasn't suggesting for a moment they were technically great games,I'd rather Project X,Superfrog etc. any day of the week, but I was trying to recall what if any games did try to make the use of the HAM mode period.
I'll admit that whilst the "copper chip" effect worked well for some games, there were other's where the use of it became mundane, compared to the mult-colour background scrolling on games like Shadow of the BEast or Unreal for example.
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Old 22 June 2002, 22:00   #20
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Wasn't Pioneer Plague the first HAM game for A500? Played decently smooth too, but not a very good game.
 
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