Old platforms: bring out your dead

[Daniel Palmer]

Hi Adrian,

On Mon, 11 Jan 2021 at 18:17, John Paul Adrian Glaubitz
<glaubitz at physik.fu-berlin.de> wrote:
>
> Hi Daniel!
> > On Sat, 9 Jan 2021 at 07:56, Arnd Bergmann <arnd at kernel.org> wrote:
> >> * 68000/68328 (Dragonball): these are less capable than the
> >>   68020+ or the Coldfire MCF5xxx line and similar to the 68360
> >>   that was removed in 2016.
> >
> > I have some patches for the DragonBall series to enable SPI etc there,
> > some patches to support the SuperVZ variant, some tools to upload
> > Linux via the integrated serial bootloader.
> > The DragonBall is probably what anyone that wants to build a 68K retro
> > computer should use as the DRAM controller is integrated and it can
> > access 32MB of SDRAM.
>
> Sounds interesting. Do these SoCs come with an MMU? And do they use the
> ColdFire instruction set or do they run plain 68k code?

I can't remember if they have a simple memory protection controller or
not but I'm sure there isn't a proper mmu so they are limited to
nommu.
The instruction set is exactly the same as the original 68000 except I
think they have the one slightly different instruction like the
MC68SEC000 has.
The standard MC68000 only has 24 bits worth of address lines though so
you have to get everything into 16MB which is a bit painful if you
have 8MB of flash and 8MB of RAM.
The DragonBall must have more address lines internally however as I
managed to get 32MB of SDRAM and 16MB of flash working on my board.

It's still a toy at the end of the day though. :)

Cheers,

Daniel