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

allison ajp166 at
Mon Oct 31 14:49:09 CDT 2016

On 10/31/16 3:29 PM, COURYHOUSE at wrote:
> 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
> model
> of B (inherited from its ancestor BCPL)  wasn't a good match for the
> PDP-11's
> 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).
> Noel
> 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..
At that time PDP-11 was a general architecture name and 11/mumble was a 
specific system.
Keep in mind that new versions of the -11 would evolve soon after 
introduction and
continue over time for decades.

Add to that there were both processor naming and system configuration naming
> 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.)

Find a copy of the PDP-11 systems handbook!  Say 1978, 80 and 82 
versions and
see the difference.  Never mind the Unibus, Qbus, PRO, and PDT flavors.

> thanks Ed Sharpe  _www.smecc.org_ (

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