Re: NetBSD without MMU ?

[David Laight <david%l8s.co.uk@localhost>]

On Fri, Apr 12, 2002 at 11:35:39AM -0700, Byan, Stephen wrote:
> 
> BTW, the PDP-11/20 and PDP-11/40 didn't have memory mappers; that was an
> option for the PDP-11/45.

IIRC the pdp 11/40 did have an MMU - used to expand the 16bit virtual
address out to the wider physical bus.

RSX/11M used the MMU to swap processes into different physical
addresses, some programs (eg the task builder aka linker) used it
to get their resident size above 64kb - useful for linking moderate
sized programs, but had to be restricted to use less that all the
available memory for very large ones.

RSX/11M didn't page - only swapped, indeed (from experiments putting
all the swap space onto an 8" floppy drive) might have swapped
synchronously!

Neither the 11/10 nor the 11/03 had an MMU.

        David

-- 
David Laight: david%l8s.co.uk@localhost