[pups] Unix and PDP11/20 (was PDP9?)

[cdl@mpl.ucsd.edu (Carl Lowenstein)]

> From: Dennis Ritchie <dmr at plan9.bell-labs.com>
> Subject: [pups] Unix and PDP11/20 (was PDP9?)
> Date: Wed, 4 Sep 2002 00:21:40 -0400
> 
> I'm not positive about the logo on our first PDP-11.

The text accompanying the picture "Ken and Den" somewhere on your web site
says that the logo on your first PDP-11 was just "PDP-11" without the /20.

> On the earliest handbook I have, the front panel photo
> just shows "PDP11", though inside the handbook
> it does talk about the two models (11/10 and 11/20).
> Both had the same KA11 processor, but the basic
> 11/10 sported 1024Kw ROM memory plus a generous
> 128 words of RAM, while the 11-20 had
> 4096Kw core RAM, and the ASR33 Teletype was included.
> You could add more RAM to the 11/20.

I fear that you have suffered a "units slip" saying 1024Kw
and 4096Kw when you meant 1Kw and 4Kw respectively.

> Incidentally, the machine's handbook was a wonder.
> In 104 pages (each 5.25x8 inches), it described the whole
> system: not only the instruction set but the theory
> of the Unibus (including some logic diagrams) together with
> programming specifications for the TTY, the clock,
> and the paper tape reader.
> 
> 	Dennis

Agreed, "PDP11 Handbook Second Edition" was a really good book
Occasionally I wonder if I ever had my hands on a "First Edition"
and threw it away when the second edition came out.  Not knowing
that both the computer and the handbook would become classics.

    carl
-- 
    carl lowenstein         marine physical lab     u.c. san diego
                                                 clowenst at ucsd.edu