Coldfire - Binary Compatible

[Crumb]

@JimS

Data and code is not splitted in 68k code so that's probably not an easy task and that's the reason JITs exist.

[Crumb]

@bloodline

If I am not mistaken, raw performance of intel ARM cpus is half the performance of PPC cpus (even embedded ones).

If I was desgning such a board for classic I would probably choose a low-power PPC chip (as it's very cheap, offers PCI, memory controller, usb and other stuff and could bring the possibility of running MOS/OS4). Or maybe an x86 low-power single-core chip (but this could turn much more complex and expensive).

I guess that interfacing a modern x86 chip to an Amiga classic bus would be quite complex: 0.5 to 1 Ghz memory buses, you would need to build some kind of "northbridge" to communicate the amiga hardware with it... and I think it would be much more easy with an embedded PPC chip (memory bus is slower so board layout is easier), these include nice controllers built in for SATA, PCI, ...

With a 68k->PPC JIT a modern embedded PPC chip running at 1Ghz would probably offer better performance running 68k code than a 68->x86 JIT on a single core low power x86 cpu.

IMHO an accelerator's cpu shouldn't require much more than 18watts.

[Crumb]

Don't sprout this 20 year old rhetoric... the performance of a modern architecture is now very dependant upon implementation. The ARM Cortext A8 offers the same MIPS/MHz ratio as the 3 core IBM Xenon, and uses less power.

Well, ARM performance usually sucks compared to normal cpus, just like VIA C7 sucks compared to AMD and Intel cpus. I don't care much about tweaked benchmarks.

The big difference between the PPC and the ARM... is the number of companies supplying compatible parts and the amount money being poured into development... i.e. the ARM has vastly more on both counts.

PPCs are cheap, specially SOC models. Just because Apple charged you a lot of money it doesn't mean PPC is expensive. Just look at the Price of Efikas.

A quick look at wikipedia will show you companies that have licensed PowerPC:

    * Altera - FPGA manufactor
    * Apple ('A' in original AIM alliance), switched to Intel starting early 2006
    * Applied Micro Circuits Corporation (AMCC)
    * Avago Technologies
    * BAE Systems for RAD750 processor, used in spacecraft and planetary landers.
    * Bandai for its Apple Pippin
    * Cisco Systems for routers.
    * Culturecom for V-Dragon CPU.
    * Exponential Technology X704
    * HCL
    * LSI Logic
    * Microsoft, for the Xbox 360 processor, Xenon.
    * Motorola (now Freescale Semiconductor), as part of the original AIM alliance.
    * Nintendo for the GameCube and Wii processors.
    * P.A. Semi.
    * Rapport for Kilocore 1025 core CPU.
    * Samsung.
    * STMicroelectronics for the MPC55xx series.
    * Sony and Toshiba, for the Cell processor (inside the Playstation 3 and other devices).
    * Xilinx - FPGA manufactor, Embedded PowerPC in the Virtex-II Pro and Virtex-4 FPGAs.

There are plenty of lower power, simple x86 variants that one could use... produced by a range of companies... and in vastly more configurations and with much more support hardware.

And these usually suck running 68k JITs because are little endian and lack big L2 cache. These also suck compared to normal x86 chips.

One would need a "Northbridge" with a PPC too... the PPC offers nothing from a hardware point of view over the x86 in terms of 68k compatiblity...

I don't know if you didn't read what I wrote or you didn't want to understand it...

PPC offers a good performance/consumption ratio, a very good price (just look at the price of Efikas). Your claims about low consumption embedded PPCs being expensive are simply ridiculous. Even desktop cpus like 970FX had decent price.

Just for your information... making a board and a "northbridge" that supports buses of 1Ghz is more complex and expensive than making a board that uses an embedded PPC.

68k->PPC JITs are faster than x86 ones. Just compare the speed of a CRAP board like BlizzardPPC, using 60ns SIMMs, no L2 cache etc and the speed of a much more powerful x86 with twice bus clock and faster memory bus.

though the PPC does offer Big Endian data format, but that is a software issue... and the ARM offers that also.

Just software? Come on! If I was doing an A1200 accelerator that would be the most important thing. It would be retarded to create an (expensive) accelerator for A1200 that didn't have good compatibility and performance. Ever wondered why phase5 included a real 060 chip on their CSPPC boards?

If you really don't care about classic software it would be quite stupid to create an incompatible accelerator for such an ancient board.

BTW, not all ARMs are bi-endian

No way!!! And certainly not for a decent price.

An embedded PPC would run 68k JITs way better than any x86 equivalent chip, it would be faster and it would have a similar price.

Then I guess that Efika owners bought their efikas for 99$ and Genesi lost 600$ with each board. Yeah, sure.

Check out the ARM Cortex A8... have a look at the power consumption at 1100Mhz (~2000 MIPS)

Phone me when 68k->ARM JITs are available and when MorphOS and AmigaOS4 runs on ARM.

[Crumb]

@Hans

I don't care much if 68k binaries could be written, because 90% of amiga software won't be rewritten.

BTW Biggun demonstrated *NOTHING* because there's no AmigaOS that runs on Coldfire. He just spreaded his theories about recompiling your binaries and making them slower on 68k just to be compatible with a handful of accelerators that run at 266Mhz and that are *slower* than a pitiful and cheap Efika/Pegasos (that at least has native PPC binaries and also can run 68k code at decent speeds).

IMHO a Coldfire would simply be a waste of time because it would not be 68k compatible. Recompiling would simply be stupid because 68k->PPC and 68k->x86 JITs are already faster than any Coldfire running native code (and since 1997-98 you have native PPC software). There are two OSes for PPC that run native PPC binaries.

What if current software is ported to Coldfire? Will it run faster than native PPC software running on Efika/pegasos/A1?-->NO

E.g.: would it be able to run Quake3 natively faster than Efika/Peg/A1?

Will it be faster running legacy 68k software? -> NO

[Crumb]

@hans

None of this changes the fact that you could produce binaries that run on both 68K and Coldfire if you wanted to.

Yes, but you have to avoid using normal instructions like MUL and "emulate" it, slowing down the execution on both cpus

[Crumb]

My old EPIA 800MHz can run the latest WinUAE perfectly!!

And an Efika running MorphOS would run rings around it when running Amiga m68k code.

The PPC is a well proven/documented architecture with plenty of dev software. It's quite attractive... but I don't see as much of a future as the ARM.

The 3 biggest console producers have jumped to PPC boat so I don't agree.

Really... I think you need to read up on the new 45nm chips from intel...

I doubt they offer the same performance per watt running emulated m68k code or running PPC code (OS4 and MorphOS are attractive to Amigans, don't you know?)

The PPC offers a mature platform for a company that wants to put a CPU core on their ASIC... but I don't see much advantage for a company wanting to build an accelerator for an Amiga.

Running AmigaOS3/OS4/MOS software perhaps?

A x86 or ARM will be cheaper and more long term solution...

I doubt it.

That is a pointless paragraph... my £30 2.5Ghz Athlon64 can run a JIT sooooo much faster than my 240Mhz BlizzPPC... so what?

That is a pointless reply as you would never put a power hungry Athlon64 in an A1200 accelerator.

If we are going to talk cost/performance... nothing even comes close to the x86... nothing can... the shear amount of development and scale of production, can't be matched.

I was talking about Amiga accelerators (that need to be low-power and run m68k and PPC software) and you have started  talking about x86 vs PPC.

The biggest flaw with the PPC boards...

The biggest flaw would have been investing 800€ on an accelerator with no software. No one would have bought it.

they should never have had a 68k on them. I guess they needed to ensure good compatibility, and didn't have enough time/money to develop a 68k emualtor that would have allowed AmigaOS to run on the PPC and still be able to match the timings properly... it's not an easy task!

Running the entire OS under emulation wouldn't have been fun

Not true, especially if you add in the cost of the support hardware.

VIA cpus or AMD low power cpus aren't exactly brilliant running m68k or PPC software

Of couse not... but for $150 I could buy a x86 system that would wipe the floor with the Efika in terms of performance... but the efika isn't designed for performance it has other priorities.

But for that 150$ wouldn't be low power and run m68k and PPC software at decent speeds.

[Crumb]

@Hans_

I think that comparing a reimplementation with an emulator is like claiming that modern x86 chips are just emulators because they internally work as RISC cpus and simply have x86 interpreters.

[Crumb]

Maybe it would... I don't have an Efika to test... but my EPIA is 6 years old and only cost just over £100 back then... it runs rings around my 25Mhz 040... but has full compatibility with my A1200...

Then imagine how fast would it run your OS if you had the chance of running your 68k apps together with native PPC apps.

They really will outperform any PPC Performance per watt, as for PPC code... well I don't really care about that

Most of amigans do. Just check out the interest in MOS/OS4. And it's much lower than it could be due to expensive hardware (or unavailable OSes).

But you would put a PPC 970 - G5?

On an Amiga Classic cpu? Probably never. I think that embedded models with built-in stuff are far more appropiate.  Even if you fitted a low power 970Fx you still would need a big and expensive northbridge and memory controller. Embedded models include the memory/pci/sata/usb controller

No, exactly... I appreciate that... it's just a shame, that is all.

I think that CyberstormPPC/BlizzardPPC were more or less OK at the time. Don't get me wrong, a CyberstormG3/G4 would have been very nice with a JIT or maybe even an embedded emulator but it's a pity phase5 died before releasing it.

But how much Amiga PPC only software, do you have that you couldn't do without? really?

I could probably live without amigas too, but it would be much more boring.


BTW, graphics are much faster on Amithlon/MorphOS/OS4 than on UAE.