Arcade / Console --> Amiga conversion discussions

[ovale]

These rants are SO annoying...

I think Anima writes here with the spirit of see what can be done on a the Amiga by talented coders like him. I guess he is moved by intellectual curiosity not because he want to troll or show superiority of ST over Amiga.

If possible, please keep the conversation technical.

[Miggy4eva]

Originally Posted by ovale

These rants are SO annoying...

I think Anima writes here with the spirit of see what can be done on a the Amiga by talented coders like him. I guess he is moved by intellectual curiosity not because he want to troll or show superiority of ST over Amiga.

If possible, please keep the conversation technical.

Agreed 100%, these rants are extremely annoying and off topic. AnimaInCorpore is very good to share his sprites and assist with Amiga conversion. But all the other ST peasants posting in here are taking it off topic.
I compare to the ST, say the Amiga port could destroy this ST port not to compare platforms but to explore the conversion of Amiga port.
The ST port of Ghouls n Ghosts is very useful and helpful for discussion of Amiga ports because it shows that such a port is easily achievable on the A500 OCS, if it can be done on the ST as per the video.

[kovacm]

Originally Posted by Miggy4eva

Agreed 100%, these rants are extremely annoying and off topic.

Rants are annoying?

You are one who start trolling, asshole. We were just fine without you!

[Miggy4eva]

Originally Posted by roondar

Besides, the notion that the Amiga can do anything the ST does better is misinformed at best. The Amiga has great hardware and it allows it to do many things better than the ST (especially when concerning 2D action games), but the ST/STE have their own advantages which sometimes are more important than having sprites, a Copper or a Blitter. These include memory layout, bitmap layout in memory, a faster CPU and a faster memory bus and (as far as I've seen) faster disk/harddisk access.

Faster RAM of ST is easily overcome by DMA access in OCS so that Blitter and Copper can access RAM while the CPU still works.
Every advantage the ST has is 1 step forwards, 5 steps backwards. 3d is faster on the Amiga with help of blitter to fill the polygons, which makes the TINY bit faster CPU irrelevant.
OK, no more on Amiga vs Atari! Maybe start another thread for that........

Originally Posted by roondar

You see, I think copying from fast to chip can be a very useful technique for improving performance. The same goes for running the code from fastram. Some ideas I got reading the last few pages here:

• Running all code in fastram, allowing the Blitter to freely use all memory bandwidth
• Using the CPU to create a dynamic copper list (which in turn does all blitting) in fastram, copying it over to chipram when done
• Storing graphics, SFX, etc in fastram and copying it to chipram only when needed. Key here would be to limit the rate at which copying is done to minimize overhead and selecting which graphics to store where intelligently
• Using the CPU to 'pre-render' effects such as rotation in fast memory and copying over only the result when done (which lowers the 'effective cost' to merely the copy action and not the whole rotation as that is done while the Blitter can still run at full speed)
• Playing all audio from tiny chipram buffers that are refreshed by the CPU from fastram, limiting memory overhead for audio and increasing memory available for graphics cached in chipram
• etc..

Great list and great ideas. Also I think we do not have to go to such great trouble.
My idea is this: 2MB of Chip RAM is a very large amount to play with, more than most OCS games ever used and more than most games on any platform or arcade machine in the era used.
Simplest solution is to run code in Fastram, yes, and then also use the rest of Fastram as a big RAM disk. Then load data on demand, instead of from slow floppy or hard drive just have all the sprites and data in the RAM disk in fastram. Instant loading when required.

[Amiga1992]

Originally Posted by Miggy4eva

these rants are extremely annoying and off topic. AnimaInCorpore is very good to share his sprites and assist with Amiga conversion. But all the other ST peasants posting in here are taking it off topic.

Funny coming from you, who took this to off-topic-ness by overstating Amiga capabilities without even having any kind of solid knowledge of how Amiga hardware (or any otehr hardware) actually works.

Here's another bit of really "funny" misinformation you are passing off as a "fact" but it's actually a load of old bull:

Originally Posted by Miggy4eva

2MB of Chip RAM is a very large amount to play with, more than most OCS games ever used and more than most games on any platform or arcade machine in the era used.

Or

The ST port of Ghouls n Ghosts is very useful and helpful for discussion of Amiga ports because it shows that such a port is easily achievable on the A500 OCS

You are as bad as the "ST peasants" you criticize so much. No fanboyism is needed in this thread, only analytical reality, of which you are providing none.

[Miggy4eva]

YOu have spent more time complaining about me than I have taking the thread off topic.
I will not reply to such posts anymore.

[DamienD]

Ok, just read through the last 2 days posts here...

@kovacm; what the hell?

Originally Posted by kovacm

So I must start to collect and document these bullshits: http://milan.kovac.cc/atari/dlfrsilver/

and if Miggy4eva continue with trolling around he will also get place in "hall of shame"

As someone already mentioned, are you that sad to be "documenting" discussions and then creating webpages to slag people off?

Keep it up and you'll most definitely be getting banned from EAB permanently

[DamienD]

...forgot to mention in the above post.

@everyone; back on topic please.

Enough of the Amiga vs Atari ST flame wars rubbish.

[zero]

In terms of an interesting project I think an A1200/030 with a few megs of fast RAM could do some very impressive stuff that hasn't really been seen before in games, or even in demos.

Having said that I think few games ever really found the maximum potential of the basic A1200 because the AGA versions were often just ports or updates of the OCS version. It's a lot like how the Amiga got many crappy Atari ST ports before Beast came along and showed what was possible.

[ovale]

IMO a port for accelerated Amiga doesn't have any appeal. To use the 030 to draw stuff in a frame buffer is no more Amiga-ish than the same code running on a Mac. At this point I prefer to play with MAME.

For me it should be a A500 with fast ram. This is a challenge comparable to the STE.

[sandruzzo]

Originally Posted by ovale

IMO a port for accelerated Amiga doesn't have any appeal. To use the 030 to draw stuff in a frame buffer is no more Amiga-ish than the same code running on a Mac. At this point I prefer to play with MAME.

For me it should be a A500 with fast ram. This is a challenge comparable to the STE.

030 would help Blitter to do stuffs. Even 1200 with fast ram is good as target machine!

[kovacm]

Originally Posted by ovale

IMO a port for accelerated Amiga doesn't have any appeal. To use the 030 to draw stuff in a frame buffer is no more Amiga-ish than the same code running on a Mac. At this point I prefer to play with MAME.

For me it should be a A500 with fast ram. This is a challenge comparable to the STE.

For me is also most impressive what people can pull out of stock machine.
On other hand, Amiga by design have FastRAM capabilities so it is "stock" in my book FastRAM did cost as "normal" RAM, right?

And Amiga 500 with FastRAM would greatly surpass STe so STe have no chance.

[roondar]

Originally Posted by kovacm

For me is also most impressive what people can pull out of stock machine.
On other hand, Amiga by design have FastRAM capabilities so it is "stock" in my book FastRAM did cost as "normal" RAM, right?

And Amiga 500 with FastRAM would greatly surpass STe so STe have no chance.

I've never understood why Commodore didn't have the A500 trapdoor expand true fast memory instead. Yes, it would've been more expensive, but it would've made the machines much faster (especially in situations were the chipset is taxed).

And when they released the A500+/A600 they made the same mistake again...

Mind you, I never understood why sidecar expansions for more memory didn't take off either so it could just be me

[dlfrsilver]

Memory at this period was very expensive unfortunately. Otherwise i guess people would have invested in more ram.

[kovacm]

Yes, Amiga original was planed with 256KB of RAM...
Atari ST also have Atari 260 ST (256KB RAM) version but it never hit the market.

@roondar what is "true fast memory" for A500?
In A1000 and A500 you have:
1) chip ram / custom chips can access it, access shared with CPU
2) slow ram / custom chips can NOT access it, but access shared with CPU (same as chip ram)
2) fast ram / custom chips can NOT access it, access is at full CPU speed (custom chip can not slow/block CPU access to this ram)

what I am not sure is what people usually have back in 80s and 90s. Do Amiga users expand their A1000/A500/A500+... with slow ram or fast ram...? Was there difference in price (fast vs slow ram)?

I did have Amiga 500 only later, somewhere in 1993. to play some games and it had 1MB total - 512KB in trap door of slow ram I believe.

[roondar]

Originally Posted by kovacm

Yes, Amiga original was planed with 256KB of RAM...
Atari ST also have Atari 260 ST (256KB RAM) version but it never hit the market.

@roondar what is "true fast memory" for A500?
In A1000 and A500 you have:
1) chip ram / custom chips can access it, access shared with CPU
2) slow ram / custom chips can NOT access it, but access shared with CPU (same as chip ram)
2) fast ram / custom chips can NOT access it, access is at full CPU speed (custom chip can not slow/block CPU access to this ram)

Basically, RAM put in the trapdoor is slow ram (or fake fast ram). RAM on an sidecar expansion is fast ram (which I call 'true fast memory' because the OS will report slow ram in the fast ram category).

what I am not sure is what people usually have back in 80s and 90s. Do Amiga users expand their A1000/A500/A500+... with slow ram or fast ram...? Was there difference in price (fast vs slow ram)?

Almost everyone had trapdoor expansions, hence slow ram. Mainly because sidecar expansions where more expensive.

Which is why I lamented Commodore's decision to not have the trapdoor provide for fast ram instead of slow ram. I understand it would've been harder/more expensive, but it was still a missed opportunity.

Especially so for the A500+/A600.

[frank_b]

For the 500 it all depends on how much sprite data is required in a level.

Tile data can be stored in fast RAM and copied with the CPU. They don't need to be shifted.

Masked and shifted graphics data on the Amiga really needs to be accessible via the blitter. The 68000 is too slow unless you preshift which likely isn't an option if the data is very large. You could always buffer from fast to chip then render but there's a cost.

In ideal conditions the Amiga blitter runs at 8 CPU clock cycles (4 dma ticks) to mask a single word to the screen. It's generally slowed down by other DMA access. If the CPU were to copy from fast to chip 32 bits at a time, then you're looking at opcode read (4 cycles), (32 bit read 8 cycles) and another write (8 CPU clock cycles) to get 4 bytes of data into chip RAM. Your best case 8 cycles is now up at 8 + (20 /2) for 16 bits. it's literally twice as slow. You might save some cycles with a movem.l copy but it's still going to hurt.

Actually it's worse than this.. I forgot that you need to buffer the mask too
I think the STe wins here if the sprite data is massive. An ST or STe can use all of the 24 bit range for its blitter. Add a monster card and you can have 12 meg of sprite data if you want. It isn't doing two pass masking either. It's a line by line fringed copy due to the intelligent end masks. Ie worst case 12 cpu cycles per word with a best case of 8 excluding overhead. It is really fast at blitting with this technique.

It would be good to see an a500 version though

[dlfrsilver]

Originally Posted by frank_b

For the 500 it all depends on how much sprite data is required in a level.

Tile data can be stored in fast RAM and copied with the CPU. They don't need to be shifted.

Masked and shifted graphics data on the Amiga really needs to be accessible via the blitter. The 68000 is too slow unless you preshift which likely isn't an option if the data is very large. You could always buffer from fast to chip then render but there's a cost.

In ideal conditions the Amiga blitter runs at 8 CPU clock cycles (4 dma ticks) to mask a single word to the screen. It's generally slowed down by other DMA access. If the CPU were to copy from fast to chip 32 bits at a time, then you're looking at opcode read (4 cycles), (32 bit read 8 cycles) and another write (8 CPU clock cycles) to get 4 bytes of data into chip RAM. Your best case 8 cycles is now up at 8 + (20 /2) for 16 bits. it's literally twice as slow. You might save some cycles with a movem.l copy but it's still going to hurt.

Actually it's worse than this.. I forgot that you need to buffer the mask too
I think the STe wins here if the sprite data is massive. An ST or STe can use all of the 24 bit range for its blitter. Add a monster card and you can have 12 meg of sprite data if you want. It isn't doing two pass masking either. It's a line by line fringed copy due to the intelligent end masks. Ie worst case 12 cpu cycles per word with a best case of 8 excluding overhead. It is really fast at blitting with this technique.

It would be good to see an a500 version though

as roondar explained, the sidecar expansion port is the port on the left of the A500. It supports up to 8mb of ram (fast type).

I remember that Richard Aplin explained on an old topic on EAB that Strider could have been arcade perfect on A500 with 8mb of ram, the whole lot with the triple playfield. With lots of memory, you can do a lot of things.

But anyway, the problem remains the same : lower the RAM specs and only loads the required sprites and tiles in memory.

[kovacm]

It looks like that many of you just talks about how everything can been "arcade perfect on A500" but can we some action?

btw dlfrsilver,
frank_b just explain (and you quote him) that it would be slow to copy data from fastram to chip ram if you need masking operation. ST blitter has no problem and can access and use entire RAM (12MB if you put as much in ST ).
I am eager to see what Amiga folks could pull out of A500 with fast ram!

[idrougge]

Originally Posted by kovacm

I am eager to see what Amiga folks could pull out of A500 with fast ram!

Can't say I am. A game for an A500 with fast RAM is about as interesting as a game for an A500 with a 24-bit graphics card. What's the point in using a limited platform when you remove limitations on a whim?