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

John Holden johnh at psych.usyd.edu.au
Thu Sep 5 09:48:22 AEST 2002

On Wed, 4 Sep 2002, Dennis Ritchie wrote:-

> I'm not positive about the logo on our first PDP-11.

The picture of Dennis and Ken in front ASR-33's hints at a pdp11/20 logo
on the console. The 11/20 I have (built 29/1/71, SN 821) has just plain 'pdp11'.
The lead time on getting the machine was about 6 months. I suspect that the
/20 was added as other models were in the pipeline (/05,/45).

For a picture, see http://www.psych.usyd.edu.au/pdp-11/11_20.html

> Incidentally, the machine's handbook was a wonder.

Indead it was

The front cover is interesting, in that it shows a table top version of the
11/20. It was quite possible to run one just with paper tape and an ASR33 with
the reader/punch option. There was a similar option for the pdp8/e.

The only obvious change between the first and second edition handbooks was that
the latter changed the last page from a picture of a young lady in front of
a machine to a table of Unibus pin assignments.

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