Why no Amiga equiv to Firebee?

[joska]

Does anyone know? Have the Atari guys figured out how to make an efficient emulator, or are they taking the performance hit?

I actually own and use a Firebee on a daily basis. The CPU compatibility issue is addressed in several ways:

1. The CF68KLib. This handles almost all illegal instructions. It does degrade performance to some extent. Currently it runs 68k applications about 2.5 times faster than my 60Mhz Milan060.
2. A software 68k emulator for better-than-060 compatibility when needed. This is based on the Musashi 68k-emulator and allows individual processes to run in separate emulated 68k CPUs. They share memory space with the real CPU, and all OS-calls are of course run in native mode.
3. The OS is compiled for the ColdFire, no issues there.
4. Binaries are patched (move.b xx,-(sp), LineA...) when launched.

Most *applications* are running fine with the CF68KLib. Some needs to be run under the 68k-emulator, and quite a few does not work at all.

What's interesting is that the apps that don't work often does this for other reasons than the CPU. I don't know how it's like in the Amiga world, but in the Atari world there's a lot of applications that make assumptions about screen layout, sound hardware, RAM etc and when you create a new computer it's hard to get these things perfectly backwards compatible. I have a Falcon, a Falcon with a 040 accelerator and a Milan060 (Atari clone) and the problem is always the same - the previous generation of software doesn't run or run with problems.

The Firebee in it's current state is a "GEM-machine". It runs GEM applications fast and stable, about 90% of the stuff that runs on my Milan060 also runs on my Firebee.

I would love to have a fast machine with a "real" 060. But currently there it no such thing. Even when running 68k code the Firebee is faster than the fastest 060 (which I think is a Falcon with a 100Mhz CT60). And the 060 is not without issues either.

[joska]

Still, you retro fanatics probably ought to stay focused on the FPGA projects. That should have similar performance benefits with possibly better compatibility.

Maybe it's possible to implement a softcore "060" that outperforms a V4E. But currently that seems to be difficult. Also, the V4E does all sorts of stuff that must be replaced if you go for a softcore. E.g. it has a DRAM-controller, ethernet, PCI-controller...

The CPU is only a part of the equation. You need to support all the other legacy hardware too, and maybe even a cycle-exact 68k. If you replace the 68k on a Atari ST or Amiga 500 with a 060 you will still have compatibility problems.

The Coldfire is powerful enough to emulate a 68k in software when you need it. Combine that with implementation of legacy chips in the FPGA and you have a machine that can both be more powerful than a 060/softcore-based AND more compatible.

Don't get me wrong, the Firebee is not perfect. Far from it. Some bad decisions has been made that unfortunately keeps it from being as backwards compatible as it could have been. But the CPU is not the problem.

[joska]

I think there are fewer timing problems on the Amiga though. There were a few early games that ran way too fast on an accelerated Amiga but that is rarely a problem since AmigaOS 2.x days.

The Amiga had more advanced video and audio hardware than the ST. On the ST there's a lot of software-tricks that depends on a cycle-accurate 68k. So if you want to play ST-games, you need a 8MHz 68000 in many cases.

I wouldn't call the 68060 slow. The v4e ColdFire out clocks the 68060 by enough that it's going to be faster with ColdFire code but the 68060 can still hang with 68k code.

Sure, the 68060 is a good CPU, better than the ColdFire in most aspects. But there hasn't been made a 68060 this millenium. And even with the 68k emulation layer, the V4E outperforms the 060.

The 68060 also benefits a lot with 68060 optimized code.

Well, if you can compile the code for the 060 you can also compile it for the V4E with even higher speeds

Well, that depends. There are very fast fpgas that could contain a CPU faster than the v4e ColdFire. They are very expensive now but dropping in price quickly.

Yes, in the future you can almost certainly get fast enough FPGA's at a reasonable cost. But will we get anywhere if we're always waiting for the next big thing? Today the V4E is the fastest option unless you go for a completely different architecture.

The CF series doesn't look like it's going anywhere.

Absolutely true. The V4E is probably a dead-end. In the future I'm sure that a FPGA based solution would be better.

The Apollo core could be used for an Atari project as well. We could go in together to burn an Apollo only CPU or perhaps a chip with Apollo core and custom chips for Amiga and Atari. An fpga solution opens up a lot of possibilities.

Very true. Basically all you need is a motherboard with a huge FPGA and a load of connectors, and you can implement all sorts of architectures on it. But again, this is the future and not today.

It would be nice if some of you Atari CF guys could do some testing .

I just don't have the time I'm afraid.