You've got to be pulling my chain... (Ethernet) - test-drb@ccmp.vtda.org

10 Apr 1998

       Allison, this was private email, but I figure this may be
       actually of interest to the group.  There's nothing here
       personal, or insulting anyway... 

       OK.  So Allison says the HEX bus 11/44 ran a BSD variant with
       networking.  I would guess a Q-BUS CPU with memory management
       like the 11/23 and 11/73 line should run this BSD variant as
       well... what I want to know is, did the kernel fit into 64K in
       one segment, or did they spread the kernel across segment
       bounderies?  If so, how? 

       I mean, I could see overlays (in the kernel... blech!), but I
       don't remember the 11 supporting long long jumps... and address
       value was 16 bits, period.  Still, I was never great at 11
       assembly.  Could someone here give a good detailed account of
       PDP-11 segment mapping support?  Could my stack and register
       values be retained and follow while moving from segment to
       segment?  And how the hell did you tell the memory manager you
       wanted to pop to another segment, anyway?

The curious want to know....
--jmg

...
  Date: Fri, 10 Apr 1998 17:40:32 -0400
 From: allisonp(a)world.std.com (Allison J Parent)
 To: maynard(a)jmg.com
 Subject: Re: You've got to be pulling my chain... (Ethernet)

 <       I find it tough to believe that a BSD kernel with networking
 <       fit into the 64K memory segments of the PDP11... The copy of
 <       Venix I ran on my 11/23 didn't support networking and the
 <       kernel most _definately_ fit into only one segment. 

 Venix didn't, but IP and friends was developed on PDP11s!  It definately 
 fit and was run on 11/44s and the like so it would fit on an 11/23. That's 
 not to say there wasn't whole lto a swapping goin on.

 Allison