Freescale Coldfire V4s

[Iggy]

Freescale is sending my company two MCF54452VR266 samples.
These are V4 Coldfire processors that run at 266MHz with built in support for USB and PCI.
I'm going to examine how hard it would be to interface these with an FPGA based board.

[Zac67]

Just wondering - what'll you use the Coldfires for?

[Iggy]

Just wondering - what'll you use the Coldfires for?

I'm not even sure.
I originally requested them to explore building a replacement for an old 68K design my company used to sell.
When I realized Freescale still had a record of the request I asked them to ship them.
I don't think approaches like the Firebee make much sense, but I would like to see how well this V4 variant supports PCI, USB and networking.

And its cheap.

[Oli_hd]

Worth having a look at the Atari Coldfire project. Its almost finished and looks amazing! It also uses the v4e Coldfire.
Also worth googling the Elbox Dragon (Amiga Coldfire upgrade prototype)

[Iggy]

Worth having a look at the Atari Coldfire project. Its almost finished and looks amazing! It also uses the v4e Coldfire.
Also worth googling the Elbox Dragon (Amiga Coldfire upgrade prototype)

I'm familiar with both. The V4 variant I'm exploring is a little different then the one used in the Firebee.
I think the Elbox project didn't go anywhere since OS3.1-3.9 source code is not available for re-compilation.
Of course now we have AROS68K.
That might make a good base for a Coldfire based Amiga.

[smerf]

Hi,

Great news!!

See if you can get one of those chip running on an old 3640 Amiga 4000 accelarator board. I know lots of people that would be interested. A lot of people here on Amiga.org would be interested in an upgrade to the old 68000 chip in there machines.

march on old valiant one.

smerf

[Iggy]

Hi,

Great news!!

See if you can get one of those chip running on an old 3640 Amiga 4000 accelarator board. I know lots of people that would be interested. A lot of people here on Amiga.org would be interested in an upgrade to the old 68000 chip in there machines.

march on old valiant one.

smerf

THAT is an interesting idea Smerf.
How about a replacement for the 3640?

[Zac67]

A 266 MHz CPU would severly starve on motherboard RAM. There's no way you can avoid a local memory subsystem. While you're at it, don't forget to provide means to use the PCI bus (at minimum, a connector enabling you to route the bus to a replacement daughter board).

Coldfires have several software compatibility issues, so it'll be quite a feat to make present software run without problems.

[Iggy]

A 266 MHz CPU would severly starve on motherboard RAM. There's no way you can avoid a local memory subsystem. While you're at it, don't forget to provide means to use the PCI bus (at minimum, a connector enabling you to route the bus to a replacement daughter board).

Coldfires have several software compatibility issues, so it'll be quite a feat to make present software run without problems.

How about a Coldfire processor linked to its own memory and an FPGA that emulates the Amiga chipset?
Running a re-compiled version of AROS68K with the  CF68KLib library to help run 68K code.

[Piru]

See if you can get one of those chip running on an old 3640 Amiga 4000 accelarator board. I know lots of people that would be interested. A lot of people here on Amiga.org would be interested in an upgrade to the old 68000 chip in there machines.

Unfortunately this is not possible as there are differences between 68k and coldfire.

[Piru]

How about a Coldfire processor linked to its own memory and an FPGA that emulates the Amiga chipset?
Running a re-compiled version of AROS68K with the  CF68KLib library to help run 68K code.

This won't help. The incompatibilities also include the actual applications, most of which you cannot recompile.

Coldfire just doesn't work running amiga 68k applications.

[Zac67]

In theory, you could modify the binary loader to patch everything it loads by means of a database.

While this wouldn't catch anything loaded by other methods or self-modifying code it would probably work on 95% of the software. However, we'd have a very hard time building the patch database (which would require automated code search and visual inspection of candidates).

[Akiko]

I assume Elbox abandoned the Dragon because they couldn't overcome the 68k compatibility issues, there was a show held in Poland a few years ago, Elbox were in attendance and demonstrated the Dragon, but as I recall it appeared to be running slower than a bog standard 040 card.

[Iggy]

In theory, you could modify the binary loader to patch everything it loads by means of a database.

While this wouldn't catch anything loaded by other methods or self-modifying code it would probably work on 95% of the software. However, we'd have a very hard time building the patch database (which would require automated code search and visual inspection of candidates).

While I disagree with Piru that it wouldn't work entirely, he does have a point that compatibility is limited. Also, you've brought up something that always really bugged me. Self modifying code. Without a doubt one of the worst programming practices I've ever run into.
And impossible to patch for.
The first thing anyone following this idea of mine is going to have to accept is that OS' like MorphOS willl have BETTER compatibility with Amiga 68K code then a Coldfire based re-implementation.
The MorphOS JIT compiler can handle on the fly translation of 68K instructions.
The approaches needed for a slower processor like the Coldfire include the  CF68KLib library to trap unsupported instructions, patching binaries before execution,  possible 68K emulation software (much slower than a PPC), and recompilation.

It can be done, but some software simply isn't going tp run on a system like this.

[matthey]

Joska mentions about 90% compatibility with the ColdFire on the Atari with it's patching and traps:

http://www.amiga.org/forums/showthread.php?t=60771&page=3

A 68k fpga processor can handle the self modifying code better than the 68040, 68060 or ColdFire. They should be more compatible also but we will have to see what the performance is like. I expect the Natami Apollo fpga CPU will be competitive with a fast 68060. A ColdFire V4 should be faster with ColdFire code. Maybe the ColdFire could be used for I/O and (DSP like) sound processing. The fpga could then run the Apollo core if your fpga is big enough or the fpgaArcade core otherwise.