AROS68K and the Freescale Coldfire CPU

[WolfToTheMoon]

I've been following the Atari Firebee(Coldfire) project with great interest.

They seem to be close to delivering their promised product(for 599 euros which includes the 120 euros for the FPGA onboard which we would not need if the AGA would be used for legacy apps). The hardware phase is mostly over and now they're primarily busy with porting software.
As far as I can see, they have successfully managed to overcome the Coldfire 68K incompatibility with something they claim to be a "light compatibility layer".

Since AROS68K is open source(the Atari team has done some patching of the TOS source code). I'm no expert here and I'd be interested in some of the more knowledgeable members opinion, but I believe a similar process could be possible to enable full Coldfire compatibility for the AROS68K.

Why am I bringing this up? Well, the Coldfire v4 offers DDR RAM, has MMU, FPU and clocks at 266 MHZ(400 MIPS). It is also cheaper then 68060 and runs with very little power(3-5 W). For those not being able to buy what is probably going to be a very expensive NATAMI board, it might be a viable alternative to get significantly more performance out of AROS68K and their 68K systems. The Firebee can now run FireTOS at 1920x1080 resolution!!!

http://acp.atari.org/

[WolfToTheMoon]

It still won't run amiga 68k software so I don't see the point. Why not just use x86?

I agree, use x86. I'm simply asking whether it'd be possible to do a Amiga "FireBee" edition for the 68K guys. The Atari crew seem to be able to work with it just fine. Sure, you'd need to recompile apps to run on AROS68K coldfire, but at least it offers a significant performance upgrade for a decent amount of money.

One solution might be maybe to use the onboard 68K for legacy software and Coldfire board for AROS68K.

[WolfToTheMoon]

There are plenty of threads on this forum as well as the Natami forum about why ColdFire is less than optimum for the Amiga. AROS 68k probably will be part of the future for some fpga based 68k Amiga though. That is what the Natami is planning...

http://www.natami.net/

Yes, I'm well aware of the Natami and their plans. The problem with Natami is price. It will probably be expensive.
Coldfire less then optimum for the Amiga? I agree it's less then optimum for the KS/WB 3.1 combo for known issues. However, not for AROS68K, since it could be patched to remedy any issues with compatibility. The issue remains for the legacy 68K software, but that could be handled by the 68K/AGA on board A1200/A4000.

Looking at the Atari Firebee project, I think one could get a expansion board with the Coldfire CPU with similar power for lower price then Natami. It would lack Natami-specific features like Super-AGA, but it could also pack it's own graphics system that could be more powerful then Natami's if not AGA related.

[WolfToTheMoon]

Don't just look at clock speed of the ColdFire vs N68k vs 68060. The ColdFire is a cut down "cheapened" 68k CPU for embedded systems. It's not as powerful as the 68060. Sure, it has larger caches and some modern features that the 68060 didn't get way back then but adding those would have been easy had the 68060 been continued. Motorola/FreeScale didn't want the 68k/ColdFire competing with PowerPC. There is no future for ColdFire except as a little brother "embedded" CPU. The N68k project is an attempt to continue the 68k line as a powerful processor. The 68k was abandoned because of marketing reasons before it's power was explored. The N68050 should already be on par with the V4 ColdFire at a lower clock speed while the N68070 should easily outperform it. Parallel processing is a big part of the reason why. The N68k should be much easier to program and much more Amiga compatible than the ColdFire too. If you want a cheaper Amiga than the Natami, then there is the MiniMig 68020+AGA. I'd rather go that route than try and make a cheap ColdFire based Amiga.

The 68060 does 110 MIPS @ 75 MHz
The Coldfire V4(e) does 400 MIPS @ 266 MHz

The advantages of the 68060 is that it is a fully superscalar design, while the CF V4 is only partially so. Still, your reasoning may apply to lower end V1, V2 and V3 Coldfires. I believe a CF V4(e)  @ 266 MHz is handily faster then any 68K silicon. The V5 Coldfire is fully superscalar(and 300 MHz) but Freescale will only make it for you if you order a (pretty) large number of them.

The N68050 should already be on par with the V4 ColdFire at a lower clock speed while the N68070 should easily outperform it

the key word being "should"

[WolfToTheMoon]

I recall reports of Elbox's "Dragon" which ran @266mhz effectively being about the speed of a 40mhz 68040 in real-world tests due to compatibility trapping, etc.

That's known for the AmigaOS and I'm not suggesting that.

But here we're talking about AROS68K. Which could be patched to avoid compatibility trapping on ColdFire. The only thing in question is how to provide full backwards compatibility with 68K... software or hardware emulation?


P.S. The V5 Coldfire @ 333 MHZ does 610 MIPS.

P.P.S. If what you say is true that it would be about 40 MHz 68040 in "emulated" mode, than maybe that's not that bad after all. Which memory and bus speed did Elbox's Dragon run? I'm thinking DDR2 RAM should speed up things. ATA controller is also built in V4e core.

[WolfToTheMoon]

Re-werite an OS that hasn't been finished yet to run on a CPU thats only partially compatible.

I think "re-write" might be just a tad bit too extreme. Sure, some patching would be required. I plan to maybe get an ColdFire evaluation board  once AROS68K progresses enough and test it.

Then require that apps be re-compiled for the new CPU or run in an emulation mode that provides much lower performance. The entire idea sounds kind of painful.

The way you say it it does sound painful.
But I'd like to investigate further just how much is the performance drop of using Coldfire with AROS68K and then see whether it is painful or not.

And how are you going to implement the rest of the chipset?  Is this going to be an accelerator card or a complete new computer?

It makes sense to be an accelerator card since it would be much cheaper to the end user and I would consider this to be a hobby and the lower the price the better(Also, then I'd avoid having a FPGA aboard which is expensive).

Yes the Natami will be fairly expensive, but hopefully it will offer a good level of compatibility. Your idea doesn't offer much compatibility at all.

Too early to say about compatibility. But if I can get 68040 performance of the CPU in the emulation mode, I'd be more then happy. The rest of the board should be pretty powerful(compared to classic 68K systems).

Personally, I'll stick with NG OS' and hope for better emulation as they progress.

I agree to that. I hope to develop for the future WB X(which will have emulation). This would be a fun side hobby project and it might benefit those people who'd like to keep their 68K hardware(and benefit me to gain more knowledge on the matter). I'm still undecided whether to go with something 6502-based or 68k based. Might end-up doing an 16-bit C64 clone afterall . It would be cheaper and simpler. But if I can get people interested in this, then maybe a joint effort could be made. I'll talk with some of the local Amiga users and see if anyone is interested.

It would not be a commercial project since I cannot guarantee to be able to finish it, whatever the reason. :roflmao:

[WolfToTheMoon]

@WolfToTheMoon
I don't mean to discourage you either but I see the hurdles and they are tough. The Natami team, Elbox and probably others have evaluated the ColdFire a lot. I think it would be neat to look at the FIDO instead. It's a CPU32 compatible 68k processor that's pretty neat. It's not as fast as the CF but it's cheap cheap and has some pretty nifty features. Exec would probably have to be modified for this too. I really like this 68k CPU in the bargain basement price range...

http://www.innovasic.com/products/ic/67-fido1100-32bit-comm-controller/

I've noticed FIDO but I haven't considered it. Do you think one could use a dual CPU configuration and possibly use FIDO to execute legacy 68K apps and CF to run patched AROS68K? I'd like to keep CF on board so to be able to use faster DDR memory and it would offer greater speed in native CF applications(and those that would be cross-compatible between 68K and CF).


also, feel free to name any other 68K and 6502 compatible CPUs as I'm still evaluating all options

[WolfToTheMoon]

That might make more sense. FIDO has an operating speed of 66Mhz. Considering that it is a 68000 and that a 50Mhz 68060 would probably outperform it, adding a Coldfire processor to either makes some sense.
The real trick would be getting AROS to use both processors. AmigaOS and its derivitives have never sucessfully used more than one processor.

No, that's out of the question. SMP would be too big of a hassle and even if it could be done, I'd then simply have 2 Coldfires and have one of those emulate 68K.

AROS 68K could run on both CPUs indivudally. FIDO would "simply" execute all those apps that have a problem with CF. But it complicates things, I'd need dedicated SDRAM for FIDO and sharing resources(graphics, HD, audio) could be a problem. To tell you the thruth, I'd much rather emulate 68K compatibility on CF. It's simpler, cheaper and, like I said, I'd be happy with 68040 performance.

[WolfToTheMoon]

The best solution would be to have enough demand to burn a real cpu from the N68070.

Indeed. But it must be first tested. How far are they from implementing it?

[WolfToTheMoon]

But by all means, go ahead and try Coldfire too, be interesting to see the results with AROS given that far less of the code would need trapping/emulation than with unmodified AmigaOS

Exactly... this idea of mine is specifically for AROS68K as I expect that in the coming years AROS68K will be making the biggest progress since 68K is the platform most loved by amigans and it has probably the biggest number of users and devs. Some extra performance would be welcomed, I believe, for the future growth.

[WolfToTheMoon]

There's nothing stopping anyone from porting AROS to the coldfire right now except a lot of work and no real market incentive to do so.  Currently AROS m68k-amiga is only partially complete and unoptimized in many areas like the native chip set graphics driver, so its currently slower than AmigaDOS 3.1.  

While the m68k work is wonderful and is helping AROS to mature, I don't think it will remain much of a focus after its "done" (as in being a decent replacement for kickstart 3.1 ROMS) because the other architectures are getting all the benefits of its work, and other AROS improvements like the ongoing gallium work (supporting OpenVG and OpenGL hardware acceleration) are more likely to be worked on and targeted for ARM and x86 based hardware.

We'll see... I haven't been meaning to start any of this before AROS68K reaches a certain point where it is usable enough.

I think you're wrong. OS 3.x has many limits and while AROS shares many of them, it's open source nature could provide decent push for the classics and their users and devs. Especially if new 68k hardware arrives, be it Natami or something else.

I think that AROS has more sense for 68K then x86 or ARM. However, it remains to be seen what kind of performance and compatibility it will achieve on 68K hardware.

[WolfToTheMoon]

So, to summarize, we're talking about a V4 Coldfire with its own memory used in an accelerator installed on legacy Amigas running AROS68K (suitably modied to run on a Coldfire processor). Is this correct?

In a word, yes.

Usage? Hobby.

Why make it? To provide a hardware solution for AROS 68K. Running AROS68K natively on a V4e Coldfire would provide a noticeable improvement over even the fastest 680x0. Only apps affected by 68K/CF incompatibility would be affected and would run at 030 or 040. But, with a max of 4 GB DDR RAM, a PCI graphics card(Matrox still makes new PCI cards and they'd be willing to provide documentation, but alternatively older Radeon or GeForce cards could be possibly used, especially if supported under Gallium) and fast disk would it matter much? I think there is no 68K application that would not run EASILY on such a configuration.

Elbox Dragon was supposed to be priced at 350 euros, according to their website.

[WolfToTheMoon]

I would really like to know more about what Elbox was planning. I just downloaded some technical data from Freescale and I'm having trouble seeing how a MCF5474 could be implemented in an accelerator. The Coldfire CPU has some common instructions it shares with the 68K but the interfaces are radically different. The MCF5474 is a much more integrated product. Not quite an Soc but close.

There are some pictures of Dragon here from 2006...

http://tdolphin.org/amikrak/amizaduszki2006.php

I wonder if they'd be willing to sell the design  if it still exists?

[WolfToTheMoon]

Interesting! Looks like it relies on RTG. What, if any, Amiga legacy components are supported?

I'm trying to find some more info about it...

[WolfToTheMoon]

I was juts looking at some of the V5 Coldfires that can be found in certain printers...

They go as high as 540 MHz!!! Even emulated, any 68K apps would FLY! Man, this would be a killer CPU to test AROS on. I wonder is there any way to get these chips but not having to deal with Freescale directly?