Subject: Re: NetBSD without MMU ?
To: Byan, Stephen <Stephen_Byan@Maxtor.com>
From: David Laight <firstname.lastname@example.org>
Date: 04/15/2002 12:24:40
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
Neither the 11/10 nor the 11/03 had an MMU.
David Laight: email@example.com