From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Subject: DEC PDP-4
Date: Tue, 10 Nov 1992 17:19:40 GMT
Organization: University of Iowa, Iowa City, IA, USA

Our news server here at Iowa just died and is being reborn, so I thought
I'd do a test posting.

In looking through my July 1965 copy of "Digital Flip Chip Modules" (this
is the predecessor of the well known "Digital Logic Handbook" series, but
in loose leaf format), I came across the following references to the DEC
PDP-4 computer:

Page 8, a photograph shows a man at the console of a computer, inserting
a Flip Chip module into a test fixture.  The computer has "PDP-4" on one
side of one of the 4 visible relay-racks, in 2" high letters.  The caption
is "Computer-controlled module tester performs complete electrical tests."

Page 10 has a photo showing a man sitting in front of a Gardner Denver
Wire Wrap machine, with a bit of an IBM keypunch off to one side.  The
caption reads "Back panel wiring for PDP-7 being done automatically from
punched cards generated on a PDP-4 computer.

There is one more picture that is relevant to the PDP-4.  This is in the
1966-67 "Digital Logic Handbook" (Copyright 1966).  I believe that this is
the first edition.  On page xii is a photo that I believe shows the same
PDP-4 based module test fixture that was on Page 8 of the 1965 module
handbook.  The relay racks look like they've been rearranged, but the
console, scope, and test fixture look the same, and the same archaic
(pre ASR-33) teletype is on the worktable by the console.

These photos suggest that the PDP-4 had the following physical
configuration:

   From above      __________             __________
                  |          |           |          |   2 pairs of CAB-1
                  |          |           |          |   19 relay racks
                  |          |           |          |   (CAB-6 racks are
                  |__________|           |__________|   possible -- the
                  |          |           |          |   photos don't show
                  |          |           |          |   the difference)
                  |          |           |          |
                  |__________|    _______|__________|________
                                 |         |______|          | Test fixture
                                 |                           | panel protrudes
                                 |                           | slightly over
                                 |                           | table top.
                                 |___________________________|
                                                 _
						|\
						  \ Direction of view in
                                                    photos.

   From the side   __________             __________
                  |          |           |          |
                  |          |           | ________ |
   Raised aluminum|    PDP-4 |           ||[  ]    ||  Big ugly Tektronics
   letters on     |__________|           ||[  ]    ||  scope
   black top side |----------|           ||        ||
   panel          |          |           ||________||
                  |          |           |          |  Analog output panel
   Bottom side    |          |           |__________|  to scope
   panel is dull  |          |           |          |
   pale color,    |          |           |__________|  Test fixture console
   standard       |          |           |__________|  Test fixture 
   color of DEC   |          |  =============================   Table top
   racks at the   |          |           |          |
   time was blue. |          |           |          |
                  |          |           |          |
                  |__________|           |__________|
                      ^
                      |
           This rack is not visible
           in the 1966-67 photo,

Neither photo shows the actual control panel of the PDP-4, unless it is the
small panel above the test fixture console on the side of the right rack.

Note that the french doors on the normal front sides of the racks are
unbroken by any hint of a console or other decoration, and note that all
of the console panels and the identifying PDP-4 panel are on what would
normally be called the sides of the relay racks.

					Doug Jones
					jones@cs.uiowa.edu
Newsgroups: alt.sys.pdp8