From: allisonp@world.std.com [mailto:allisonp@world.std.com]
>An aside, I"d contend the the instruction set for PDP-11 is far better
>than 80x86 (vastly better than 8086).  So the memory footprint would
>be better.  

Um...better != smaller, for all values of better.  Some would argue that
RISC style ISAs are "better", but result in significantly larger code sizes.

>that and PDP-11 And VAX instruction set are better matched
>to C as a higher language.  

In what way, other than some obscure things like pre- and post-incriment?  

>What about I&D space allowing concurrent data and code spaces?  PDP-11s
>(some) permit this for greater space than would be available as 16bit
>bare.  

Doesn't increase usable memory enough to do anything for a Linux derivative.
I vaugely recall that split I&D is required to run 2.x BSD, but I'm not
sure.

<x86 stuff deleted>

It's been a long time since I played with this stuff, but I recall you could
protect segment registers (among other things) if you were using the x86
mode that used protection rings and gates.  The details have long since
faded away.

Ken