Coldfire - Binary Compatible

[bloodline]

Hans_ wrote:
@bloodline & hbarcellos

By that reasoning, an AMD CPU is an x86 emulator too. It's not identical to the original x86 chip, but it does the same thing. Multiple companies make different but compatible versions of the same thing all the time. That doesn't make them emulators.

But you can take that argument to a stupid level... A Transistor is just a valve emulator... a computer is just an abacus emulator...

We're fully agreed that a clone (be it in an FPGA or otherwise) is not the original. Where we differ is in the definition of emulation. I agree that the end goal is roughly the same. However, the approach is quite different. An emulator is one thing, an FPGA implementation is another.

The only thing we disagree upon is the means... since we both want the same ends...

I just don't see the difference between a "Field Programmable Gate Array" programmed to behave like a chip/set of chips, and a CPU running a program  to do the same :-)

In many circuits, one would now use a Micro-controller in place of a large amount of dedicated custom built hardware.

This is why I call UAE an emulator, and the Minimig, an A500 clone. Neither are a genuine A500. To make things a little more complicated, the PIC micro on the Minimig that's connected to an SD-card slot is an Amiga floppy drive emulator, since there is no floppy drive at all, and it's making a file on the SD-card look like an Amiga floppy drive to the Minimig chipset.

I should point out that I love the Minimig and am really happy that Dennis made it!!!

I hope to buy one! But It should not be forgotten that all we are ever trying to achieve is an end result... how you achieve that should be dictated by the cheapest/most efficient route.

BTW, has anyone thought of taking the floppy emulator on the Minimig and connecting it to their Amiga? That would mean no more searching for disks.

Hans

Good idea.

[bloodline]

@Crumb

A bit off topic, sorry, but I've had a quick look around:

Compare the EPIA PX

With the EFIKA 5200B

I can't believe anyone would choose the Efika actually... Maybe I'm not looking at the right model... but really can't see the advantages... are you able to tell me?


I note you claim the C7 is bad for JIT execution due to small caches, but the Efika only has 32k L1 cache (ref) and no L2

The C7 has 64K L1 and  127K L2... (ref)

The Efika tops out at 400Mhz... the C7 is scalable up to 2Ghz... Need I go on?

Other than running PPC code there is no advantage to the PPC here  :roll:

[bloodline]

freqmax wrote:
Do we really need a softcore-68060, why not try to do 68020 (+mmu) in fpga instead? should give enough benefits without the complexity?

This is going to sound crazy after my previous rant... but probably the best idea is to clone something more like a Coldfire compatible core on FPGA... but one where all incompatible (with the 68k) instructions/addressing modes are trapped and trigger exceptions. And one where the supervisor mode functions as the supervisor mode on the 68k.

I expect the Freescale engineers carefully selected which 68k features would scale well, and/or be easy to implement simply. Then all less scalable features could be emulated (a la 68060.library etc...), that would not be particularly quick for old software, but it would run (possibly faster than on a real 68k).

If we took TobiFlex's 68k and stripped it back, it could probably be done... and would reduce the complexity/size of the core!

[bloodline]

Donar wrote:
It is possible to configure the CF68klib so that it sets up a Virtual 68k on the Coldfire (with e.g. 68060 as target), but then FPU and MMU will not work and it can not execute Coldfire Code anymore. Would it be possible to place the MMU and FPU in an FPGA'ed ChipSet?

I don't understand the question. The coldfire is not suitable to the amiga... I would hate the think how complex an FPU in an FPGA would be!

[bloodline]

Donar wrote:

Almost. Some instructions cannot be emulated, since they behave differently in the ColdFire. That's what the CF68klib manual says.

If i read page 10 onward of the manual correctly, which is about "Supervisor mode", that is only true for a CF68klib build for "User mode" :-P

There are situations where the Coldfire returns a different result, from what the 68k would return in the same situation. These are not trapped with an illegal instruction vector, and thus cannot be emulated.

Supervisor mode is totally different.

You don't need an MMU to get the CF68klib up and running. It uses the illegal instruction vector to implement missing instructions.

I was told that you need the MMU for setting up an expansion card for the Amiga with eg 68060 or CF. That's why i was nosy about having an MMU in the ChipSet.

MMU and FPU are not required for Amiga.

[bloodline]

@Donar

Yes exactly!

The MUL problem would kill a large amount of Amiga Code. Code which we can't modify, as CF68KLib suggests, because we don't have the source code.

 Supervisor mode would be very slow...

The point is not that the Coldfire can't be used... the point is that the amount of work required would be the same for any CPU... and there are cheaper faster ones available!

[bloodline]

Donar wrote:

User Mode or Supervisor Mode library doesn't matter.

I only find it strange that in the user mode paragraph it is mentioned explicitly that the differently implemented instructions will not work, and in the supervisor mode paragraph there is no word about it. It sounds like the library will set up an full 680x0 Emulator (without MMU/FPU) on the Coldfire but maybe i interprete in the text what i want to be true :lol:  

Ok, the Coldfire Supervisor mode is so incompatible with the 68k that it needs to run any 68k code in an emulator in the SuperState. This is a very slow thing to do, and negates the point of using the coldfire in the first place... Since to run Amiga code in the User mode it would also need the emulator... by now it really isn't worth using the coldfire.

Are you a coder, Donar?

No, but i think i can read...  :-)

What the document is saying (probably not very clearly), is that coldfire User mode offers a high degree of 68k compatibility, and requires only minor source code modification in order to work. But the Supervisor mode is so different to the 68k, that all your supervisor mode code must run in an emulator... Amiga code would need to run in that emulator all the time, this makes the CPU useless.

[bloodline]

Zac67 wrote:

It all depends on what you really want to achieve:
- save your old hardware from dying (expensive)
- modernize your system while keeping old software (=> emulation)
- regain a good price/performance relation (=> OS porting)

Everything else is :horse:

Beautiful summery.

[bloodline]

Donar wrote:

It all depends on what you really want to achieve:

-Having new hardware that follows in the footsteps of the AMIGA architecture (see Natami project) but is fast enough to not bore the user to death, while waiting for a window to open (as AGA will do, when you use HighRes in 256 colours).

Hacking together out of date technologies into something that is a little bit compatible to the old Amiga line of computers is not following in the footsteps of  AMiGA...

Taking the most advanced technology available to the consumer, putting it together in a new and innovative way and packaging it in a user-friendly way is following in the footsteps...

Unfortunately only Apple come close to that... and even they aren't really pushing the hardware envelope... but they are doing a good job.

And no i do not want to play Crysis in 1680x1050 on it nor do i want to compress all my DVD's to MPEG 4 or watch BluRay on it. I have a fast PC and PS3 for such things.

If we really were following in the footsteps of the Amiga, we would get all those things for free.

[bloodline]

Donar wrote:

...footsteps of the AMIGA architecture...

Hacking together out of date technologies into something that is a little bit compatible to the old Amiga line of computers is not following in the footsteps of  AMiGA...

Maybe it's not in the footsteps of the AMIGA if you think of the most advanced computer that is available on earth. But it would be in the footsteps of how things were done "differently" in the AMIGA.

But the Amiga did things differently... then everyone else did the same... what we have now is the legacy of the Amiga's different thinking.

We now need someone to think differently.

Taking the most advanced technology available to the consumer, putting it together in a new and innovative way and packaging it in a user-friendly way is following in the footsteps...

I like the idea but as i do not think that somebody who shares your vision of a new AMIGA has the funds to realize it, its just not going to happen. Somebody could cludge together an FPGA'ed Chip set and some processor in his cellar. But there is no way anybody beats Intel, AMD and NVidia with his cellar invention. :-(

Well, Audio has reached it's highest level... No one can think of any other ways of getting hardware to produce sound... Synths (subtractive and modelling) and Samplers. All you can do in increase fidelity (but at 24bit 96Khz who can tell beyond that, especially with speaker technology).

But there are projects to develop new ways of rendering graphics... With ATI and Nvidia stuck with current polygon system... others are looking to ray-tracing... maybe there are other ways... we need innovation here...

Unfortunately only Apple come close to that...

Why do you think so? Because Apple sells dual processor workstations with four cores to everyone who want's to have more than one hard disk in his computer? Ok i admit: OSX just works out of the box.

Apple now take the best technologies available, and package it in pretty user friendly boxes. That is what the Amiga was all about..

[bloodline]

Donar wrote:

bloodline wrote:

Apple now take the best technologies available, and package it in pretty user friendly boxes. That is what the Amiga was all about..

But in the end a MacPro is just a dual processor Workstation with EFI instead of a BIOS, which you could also get from Boxxtech. I would have found it interesting if they had (for example) included a Cell or DSP that could assist the XEON's for special purposes.

For what purpose...? A Cell or a DSP isn't going to offer anything over over a regular GPU and certainly nothing for the consumer price bracket...

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arnljot wrote:
Browsing for something copletely different I found this site:
http://www.cdtv.org.uk/coldfire/

This effort now seems dead since 2004. Did this have anything to do with Elbox?

No, that is Oli_HD's home project... Send him a PM :-)

[bloodline]

arnljot wrote:

bloodline wrote:
No, that is Oli_HD's home project... Send him a PM :-)

Nah, too shy :-)

Is he still working on this?

He's a nice enough chap... He'll tell you all about it if you ask him... I don't think he works on it any more, though I could be wrong.

[bloodline]

@Jarrod

I too, used to think that a static translation would be possible... Instead of arguing, I compiled some C source code (I forget the program) then assembled it to object code, then disassmbled the object code and manually tried to convert the resultant 68k in to PPC assembler... I remember hitting a wall and asking questions on this very forum only to discover that there were descisions that I needed to make that only the original coder knew the reasons for and I would only be able to determine at run time. Basically you hit the same problem the VLWI guys hit when they tried to take the RISC concept to the extreme.