7 Dec
2016
7 Dec
'16
9:12 p.m.
From: Clem Cole
DEC's Custom Special Systems (CSS) group .. build
a simple base/limi
register device, soon after the 11/20 was released.> ... So an early
version of after the original 11/20 port from the PDP-7 had this
however.....
Oh, right, I'd forgotten about that: the KS-11 - I've previously enquired to
see if anyone had _any_ documentation for this, but so far, nada.
I would look at Warren's First Edition work to
see if there were dregs
of this in that code base
Alas, I'd already had that idea (to try and at least re-create a programming
spec, at least, for the KS11). There do not seem to be any traces there,
perhaps because that code came from a document entitled "Preliminary Release
of Unix Implementation", which argues that it's a very early 'version'
of V0
(the early 'versions' weren't very formal, there was a continuous process
of
change/improvement going on, apparently).
It is also noted that the 45 class system
(45/55/70/44) had "17th"
address bit - i.e. split I/D space. I believe that this is when "magic
numbers" were really introduced so that could be supported.
No, they came in first for 'pure text' (0410):
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/sys1.c
which I would expect arrived to minimize swapping on machines with small
amounts of real memmory.
Support for user split-I/D (411) didn't arrive until Version 6:
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/sys/ken/sys1.c
although IIRC split I/D in the kernel was supported supported slightly
before it was in user - although V5 didn't:
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V5/usr/sys/conf/mch.s
so it couldn't have been much earlier than V6.
Noel