[Coco] 2-meg mem capable 6809 before the gime and coco3?

[Willard Goosey]

On Sat, Aug 22, 2009 at 09:50:48AM -0700, Wayne Campbell wrote:

> A Memory Management Unit (MMU), the MC6829, allows a M6809 based
> system to address a 2 megabyte memory space. NOTE: An arbitrary
> number of tasks may be supported -- slower -- with software.
> 
You can't accuse the Motorola engineers of thinking small.  They
clearly had great plans for the 6809 to conquer the entire universe.

Unfortunately, that didn't happen, and most of the esoteric 6809
support chips, like the MMU and the FPO9 ROM, didn't get produced, or
were only produced in small numbers.

It's not like an MMU is necesarily a complex device.  By 82 the
mainframe and mini people had been using MMUs for years.

And as a fellow on the Model 100 list reminded me, OS-9 (even Level
II) ran on other computers besides the CoCo.  GIMIX and other LII
and/or UniFLEX machines had their own MMUs.  The unique thing about
the GIME is that it's *our* MMU. :-) (Well, and maybe that it
duplicates and expands the VDG at the same time. :)

Willard
-- 
Willard Goosey  goosey at sdc.org
Socorro, New Mexico, USA
I search my heart and find Cimmeria, land of Darkness and the Night.
  -- R.E. Howard