Tony Duell wrote:
>
> > The only OS that came close to Unix for 8 bit micros was OS/9 for the
> > 6809 and
> > even then you needed a external MMU.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> AFAIK you didn't. The CoCo 2 can run OS-9 (I ran such a system for many
> years before I upgraded to a CoCo 3), and there's no MMU in that. The
> memory map is essentially all RAM (64K RAM, no paging or anything like
> that), with a little lost to I/O near the top of the address space.
>
> Of course with no MMU you didn't have any memory protection, so user
> processes could directly write anywhere in memory. Yes, this is a Bad
> Thing, but if your programs were well-behaved and didn't try to do this
> then OS-9 would work quite well on a plain 6809 + 64K RAM.
>
> -tony
Well I ran OS-9 level #1 too, but for any real work level 2 (mmu) was
needed.
I had a Coco 3 once but never got OS-9 level 2 because RS dropped the
product
line before I could save up for it and buy a memory upgrade. Also they
did
not have any real I/O for the Coco.
Ben Franchuk.
PS. With the OS9 C compiler I used only a simple variable could be used
in the switch statement. "switch( simple variable ) { ..."
--
Live "Pre-historic Cpu's" -- and you thought they were extinct.
www.jetnet.ab.ca/users/bfranchuk/index.html
Received on Mon Nov 12 2001 - 14:18:08 GMT