Re: [hatari-devel] 68040/68060, external FPU?

[Thomas Huth <th.huth@xxxxxxxxx>]

Am Wed, 9 Jul 2025 13:26:44 +0200
schrieb Uwe Seimet <Uwe.Seimet@xxxxxxxxx>:

> > it all depends if we speak of FPU as a logic part of the setup, ie sthg 
> > that can do floating point or as a real stand alone HW component.
> > 
> > In all cases, the cpu core from WinUAE can have the following values for 
> > fpu_model : 68881, 68882, 68040 and 68060.
> > 
> > and in M68000_CheckCpuSettings() we already warn if user chooses fpu 
> > internal for cpu <= 030.  Maybe a similar warning would be needed if 
> > user chooses fpu 68881/82 (ie not internal) on cpu >= 040.  
> 
> Either that, or enable/disable invalid items in the dialog as soon as the
> user selects a CPU. Preventing the user from selecting invalid settings
> is better than later saying "sorry, your selection is invalid, please try
> again".

I've checked the Motorola user manuals for the 68040 and 68060, and it
indeed sounds like the 68LC040 and 68LC060 cannot deal with external FPUs
anymore. So I now reworked the code in M68000_CheckCpuSettings() to switch
to the internal FPU in that case instead (since that's the closest config
to what the user selected).

It's not as good as disabling the entries in the GUI actively, but
considering that we have multiple GUIs (SDL, macOS, Python), and CLI and
config file to change these options, having this in a central place in
M68000_CheckCpuSettings() is still the best maintainable way.

 Thomas