Subject: DEC PDP-4

From: [email-masked] (Douglas W. Jones,201H MLH,3193350740,3193382879)
Date: Tue, 10 Nov 1992 17:19:40 GMT

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
					[email-masked]

---

From: [email-masked] (Charles Lasner)
Date: Wed, 11 Nov 1992 07:13:59 GMT

I briefly saw a PDP-4 in the Maynard Mill Complex, and it may very well
be the machine from the picture.  It had a Model 28 baudot teletype console,
and small Alco-type snap switches on the front panel.  (Much harder to use
than later designs such as the PDP-8.)

But some of those captions are confusing:  wasn't the PDP-7 not actually
wire-wrapped, but soldered like the PDP-5, and used Systems Modules?  The
PDP-9 was definitely constructed like the PDP-8, using Gardner-Denver
automatic wire-wrap equipment, so why would a forerunner be essentially
the same design?

In any case, DEC has been known to "fake" some of those pictures for the
add copy.  One rather infamous picture of what is alledgedly a PDP-15
panel actually has an 8/l panel as part of it, and upside-down!

A PDP-12 photo shows something that was never put into production: lettering
in lower-case on the silk-screen.

I was once shown the room where all the "sexy" cabinets for the early COS-300
systems were photographed.  These cabinets were painted with bright colors,
and there was even a silly plastic front plate over a TU56 DECtape, as well
as a modified TU-10 where the drive is low in the cabinet, but has a
modified control panel made to fit into the top of the lower cabinet.  All
of the machines were places over various fabrics on the floor to achieve a
"stage presence" or some sort of "office of the future" notion, etc.  Some
of these pictures are often found in early COS-300 manuals or associated
ad copy.

The level of hype throughout all these ads is consistent with the thread
about the irrelevance of "flip chips" as a concept, as opposed to the name
that became applied to the modules, regardless of actual component type.
Apparently DEC always used the same sort of ad agency, which was obsessed with
dramatic camera angles, etc., to suggest some sort of futuristic look to all
of the machines back then.

There's even a funny shot of a KA-10 with a few DECtape drives, implying that
an extra-large cabinet was the entire PDP-10 system in useful form.  Several
years later, the opposite extreme was achieved, with a poster of a typical
computer-center-like layout with an aerial view, raised floor, many cabinets,
and a legend explaining what each cabinet group was used for, etc.  A partial
version of this picture became a back cover for at least one PDP-10 manual.

cjl