For sale 128K Core RAM Industrial PDP 11/40 Massbus System

Mon Oct 31 14:29:32 CDT 2016

In a message dated 10/31/2016 6:36:17 A.M. US Mountain Standard Time,  
jnc at writes:

> From: Ed Sharpe

> was Unix or C the one  developed on the 11/20?

Both. Unix Version 1 was written in PDP-11  assembler, for the -11/20;
although that was a re-write of an earlier  version written in PDP-7
assembler. C was developed from B in good part  because the word address 
of B (inherited from its ancestor BCPL)  wasn't a good match for the 
byte addressing model. More  here:

>  From: Christian Corti

> I think the IP stack needs  separate I/D and more memory

I read that the networking code in 2.x  uses Supervisor mode (apparently it
needed more address space than was  available with only kernel, even with
split I/D).

Great History Noel! Many Thanks!
I  wonder  if the  pdp-11 was  just  called   pdp-11 at t that point or  
was   a  pdp-11/20  like we  have..
I know they are essentially the  same   at this  time  point they  got 
their  PDP 11  what  did it say on the front  panel  I wonder?
(figuring all this stuff out  for titling up  the  cards in the 11/20 
display we are  planning.)
thanks Ed Sharpe  _www.smecc.org_ (  

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