A3000, A3640, 060 adapter and internal FPU

[jltursan]

So, I've recently installed a 060 adapter in my A3640 and all in all is working fab with a LC060/50. Of course, as the 060 cpu is a LC version without FPU, I'm trying to enable the A3000's own FPU.

Is there a way to enable the onboard FPU?, maybe using J103?

[guest11527]

Is there a way to enable the onboard FPU?, maybe using J103?

No, there isn't. The 060 (and 040) lack the coprocessor interface to control the FPU, or any coprocessors for this matter.  Which on-board FPU anyhow? The A3640 doesn't have one. It uses the FPU within the 68040.

[magnetic]

Thomas
He converted is 3640 to an 060 with a voltage hack.

@ OP
No you cannot use the a3k on board fpu becuase you are using the 3640.

[guest11527]

Thomas
He converted is 3640 to an 060 with a voltage hack.

I understand, but the 3640 is a CPU card for the 68040. There is no separate FPU on this board.

[AmiDude]

I understand, but the 3640 is a CPU card for the 68040. There is no separate FPU on this board.

He's revering to the A3000's onboard FPU.

[jltursan]

Right, I'm referring to the A3000 motherboard own FPU. Seems a waste to have it and not be able to use it.

I was hoping that configuring the FPU as internal or maybe a hack on the fast slot will do the trick...

[Acill]

Right, I'm referring to the A3000 motherboard own FPU. Seems a waste to have it and not be able to use it.

I was hoping that configuring the FPU as internal or maybe a hack on the fast slot will do the trick...

When you use an EXT cpu card you take the internal one along with its FPU out of the loop. The 060 also isn't compatible with it. I would just keep an eye out for a full 060 on ebay. You can find them for a good price as long as your not looking for the one that people OC all the time. A standard RC060/50 is fine.

[guest11527]

When you use an EXT cpu card you take the internal one along with its FPU out of the loop. The 060 also isn't compatible with it. I would just keep an eye out for a full 060 on ebay. You can find them for a good price as long as your not looking for the one that people OC all the time. A standard RC060/50 is fine.

A full 68060 just won't work with only the adaptor in place. It requires an additional DiagRom to disable the FPU during startup.

[Iggy]

A full 68060 just won't work with only the adaptor in place. It requires an additional DiagRom to disable the FPU during startup.

There is something I was not aware of.
Full '040 and '060 cpus need to have their fpus disabled during boot.
Interesting.
Why?

[guest11527]

There is something I was not aware of.
Full '040 and '060 cpus need to have their fpus disabled during boot.
Interesting.
Why?

No, only full 68060 with FPUs require their FPU to be disabled. The 68040 is fine.

The problem is that the idle stackframe of the 68060 FPU is not compatible to the stackframe of all other motorola FPUs. This has two problems: First, the FPU test of the bootstrap code crashes due to the wrong stackframe, and second, the context switch code of the exec task scheduler also corrupts the stack for the very same reason.

A small boostrap code, typically (though not fully correctly) provided by an F-space debug rom disables the FPU before the Os boostrap code starts.

The 68060 FPU is then re-enabled by the 68060.library which also exchanges the exec context switch code and installs a couple of related compatibility patches to adjust to the incompatible stack frame of the FPU.

[psxphill]

A small boostrap code, typically (though not fully correctly) provided by an F-space debug rom disables the FPU before the Os boostrap code starts.

It's a pity that commodore went bankrupt around the time the 68060 was introduced, or we have had had kickstart 3.2 (or maybe even 3.1) that avoided the problem.

And of course it's also a pity that in the following 22 years there has never been another kickstart :/

[guest11527]

And of course it's also a pity that in the following 22 years there has never been another kickstart :/

Look, I asked in this very forum who would be interested in buying such a kickstart, and all I received was "we want it for free" and "go home."

So what exactly do you expect to happen?

[Oldsmobile_Mike]

Look, I asked in this very forum who would be interested in buying such a kickstart, and all I received was "we want it for free" and "go home."

So what exactly do you expect to happen?

LOL.  Typical Amiga user responses.    There is the Cloanto "3.X" ROM, but from what I've seen on the forums, it's pretty buggy.  IMHO 3.1 ROM's + a ton of updates loaded in with LoadModule and LoadResident commands are the way to go, unless you've got the capability to burn your own custom ROM's.  Otherwise there's too many variables, you're never going to please all the people all the time.

Then you've got the people who vehemently oppose even upgrading from 3.0 to 3.1.  I just SMDH at them, it's like, less than $20 USD, for chrissake.  

[amiga1260]

You can use on the adapter a full 060, but you need a modified kickstart ROM with Exec.library.

I think Cosmos can help you with it.

[Iggy]

You can use on the adapter a full 060, but you need a modified kickstart ROM with Exec.library.

I think Cosmos can help you with it.

Thank you (and Thomas) for the education.
The owner of the company I used to work for that built 68K based systems died as we were readying a 68030 model.

The jump from the '020-'030 cpus to the '040-'060 cpus is pretty complicated.

I'd already seen beta copies of Win 3.0 (from IBM) before we closed shop, so I felt kind of doomed anyway.

Nothing like realizing that market domination was going to result in an inferior system becoming the standard.