Subject: Canonical Flip-Chip Terminology

From: [email-masked] (Douglas W. Jones,201H MLH,3193350740,3193382879)
Date: 19 May 1994 16:23:32 GMT

Charles Lasner and I were hashing over bugs in my FAQ when we noticed that
we were using incompatable terms for the dimensions of various size of
flip-chips, so last night, I wandered through my collection of DEC Logic
Handbooks, and verified the terminology preferred by DEC:

      <---------------- height --------------->

       ___\__/___________   ______   __\__/___     
      |  |____|          | |      | | |____|  |    /|\
      |  _ _             |_|      |_|         |     |
      |   | |                                 |     |
      |   | |                                 |     |
      |   | |       quad height               |     |
      |  _|_|                                 |     |
      |           extended length             |     |
      |                                       |     |
      |___\__/______\__/___         ___\__/___|   length
      |  |____|    |____|  |       |  |____|  |     |
      |                    |       |          |     |
      |   double height    |       |  single  |     |
      |                    |       |  height  |     |
      |  standard length   |       |          |     |
      |                    |       | standard |     |
      |                    |       |  length  |     |
      |_        __        _|       __        _|     |
        |      |  |      | |      |  |      |       |
        |______|  |______| |______|  |______|      \|/

The term width is used by DEC to refer to the thickness of the board.
Most boards are single-width, but some have big components on them that
make them double width.

The terms height, width, and length are used uniformly in all board
dimensional drawings I've been able to find, from the the 1966-67
logic handbook to the 1978 logic handbook.

Having started using DEC equipment in the PDP-11/20 era, it's very
tempting for me to think in terms of an OMNIBUS board being quad-wide,
extended height, but none of my DEC documentation uses the terms this
way, so I guess, since I also deal with older stuff these days, I'll
try to stick to the "official" terms from now on.

				Doug Jones
				[email-masked]

---

From: [email-masked] (Mike McCrohan)
Date: 26 May 1994 18:36:19 +0100

> Handbooks, and verified the terminology preferred by DEC:
[Neat graphic snipped]

> logic handbook to the 1978 logic handbook.

I almost agree, but for a matter of detail. I spent from 1971 to 1980 as
a technician/engineer working in Digital Manufacturing. The Height of
the board was the dimension measured from the gold fingers to the plastic
handles, and the Width was measured along the fingers. The thickness of
the board was always referred to a so many layers.
The number in the height dimension is the number of sets of fingers on a
board. Original boards had one set of fingers and thus were single
height. Quad height appeared around the time of the 11/20 and 8/e, and
Hex in the 11/05, 11/40 and most other machines of that era.
The width dimension of the original  single width boards would have been
between 3 and 4 inches. Double width were already well established
before the 11/20.
The 11/20 was constructed from single, double and quad height boards -
all double width. The 8/e is all dual height quads.
When the 11/780 was introduced so was the "extended hex" board. Still
hex width but about 2-1/2 height.

Trivia: (Mention of the fingers reminded me)
        What letters are missing in the DEC Alphabet? And where is that
        alphabet used? And why are those letters missing?

---

From: [email-masked] (PDP11 Hacker .....)
Date: Thu, 26 May 1994 20:02:00 GMT

In article <[email-masked]>, [email-masked] (Mike McCrohan) writes...
>the board was always referred to a so many layers.

To me, the number of layers of a circuit board refers to the number of copper
layers in the PCB - for example, most of the boards in my 11/45 are 4-layer as
they have circuit traces on both surfaces, and internal power and ground
planes. Are you saying that DEC used the term layers to refer to the number of
slots across a backplane that a module would cover?

>all double width. The 8/e is all dual height quads.

That's inconsistent, surely. As I understand the terms, the 11/20 was made from
single, dual and quad height boards, and the 8/e was all quad _height_ dual
length. That's the way the terms are used in my DEC logic handbook.
Anyway, if you are having quad height boards in an 11/20, you'd better have
them in the 8/e as well...

>        alphabet used? And why are those letters missing?

A,B,C,D,E,F,H,J,K,L,M,N,P,R,S,T,U,V  - the letters of the pins on a standard
(flip-chip) board slot.
Missing are 
G (looks like C??)
I (confusion with 1)
O (confusion with 0)
Q (ditto)
W,X,Y,Z (too few pins :-))

-tony

Bristol University takes no responsibility for the views expressed in this
posting. They are the personal views of the user concerned.

---

From: [email-masked] (Frank R. Borger)
Date: Thu, 26 May 1994 22:14:21 GMT

>        alphabet used? And why are those letters missing?

	Let's see, the alphabet according to Ken needed only 22 letters,
	to match the 18 pins...

	A B C D E F (no G)		Can be confused with 6 or C
	
	H (no I) J K L M N (no O) P	I looks like 1, O looks like 0

	(no Q) R S T U V		Q easy to mistake for O

	and no W X Y Z	

	Memory fails me, but wasn't that a standard somewhere before? Anyway
	I still buggered at times trying to determine whether it was U or V
	on a blurry print.

Frank R. Borger - Physicist     ___      What's the best way to tune a Banjo?
Michael Reese - U of Chicago   |___      With an Axe! -  What's the difference
Center for Radiation Therapy   | |_) _   between a dead skunk and a dead banjo
net: [email-masked]    | \|_)  player on the road? The skunk was on
ph: 312-791-8075 fa: 791-2517       |_)  his way to a gig!