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Origin of X




I have seen discussions of X in this list.  I haven't read everything,
since I am trying to close a backlog, so I appologize if some of the
things I write here have already been said on the list.

The X Windows project has been part of the Athena project in the MIT
Computer Science Lab.

Before X Windows was born, there were a number of computers or workstations,
running some Unix flavour, that had a graphical windows user interface.
Some that can come to mind are SunView from SUN and Apollo.  The problem was
that the graphical interface of each machine was different from that of other
machines.  That means that it is very difficult to construct a heterogenous
environment, where you have workstations from different manufacturers, since
they are not compatible.  MIT had SUNs and DEC workstations and others, and
there was a problem for the students and stuff, who needed to choose in
advance the type of machine on which the student will need to work on a project.

The X project came to change this.  X Windows has been a revolutionary concept
at its time, and it presented the following new concepts (I don't have any
pretentions that this list in conclusive, but I hope it emphasizes the high-
lights):

1. The separation of the display, or server, from the application, or
   client.  The client can run on one machine and the server can be another
   machine.  Of course, the two machines must be connected.
   In order to accomplish that, the X protocol has been devised.
   The X protocol can be applied over TCP/IP, but also over other types of
   network protocols.

2. X Windows does not dictate policies.  It provides a mechanism that tool sets,
   such as the Motif Widget set or Athena Widgets, can use to design and
   implement their own look and feel.

3. The X protocol is expandable, and allows for the creation of Extensions.
   It is not mandatory for each server to support any extension.  Only the
   basic capacities must be supported, that is, the X11 protocol itself.
   Some extensions that were created to the X protocol are:

   a) PEX - 3D graphics extension , to better exploit smart graphics engines.
   b) X Input extension - Allows for other input devices besides keyboard
	  and mouse, e.g.: tablet.
   c) SHAPE - Allows for non rectangular windows (oclock).
   d) XSERIAL - Allows for the use of a serial line to transfer X protocol.

   There is also an extension to display postscript, and other extensions
   which I will not write down here.

The X project has been supported by Digital from the start.  As time passed by,
more and more computer companies jumped on the wagon, since the idea was to
standardize user interface between platforms, and to allow for a uniform
base for a window system.  Of course, the look and feel on each machine
could have remianed different.

Consequently, the X Consortium has been founded, where the member companies
paid membership dues to finance the development of X.  With their dues came
also their ability to have a say on what was to be developed and over what
basis.  They also got early (alpha, beta) releases of the new software, etc'.

An important point to be made is: The final version of the protocol is X11,
and it hasn't changed for probably 10 years.  What the X consortium did later
was to develop sample code for the server, for the extensions server part,
for the XLIB library and the extensions client library sides, for the Xt
toolbox library, for the Athena widget set, etc'.  The sample code has been
the basis for the vendors code for the server and libraries.

The person heading the effort was Bob Scheiffler (also known as "reverand Bob"
and by other names).  He headed the effort when it was in the hands of MIT,
and I think he is still involved with the X consortium today, when the consrtium
is not headed by MIT anymore. 

-- 
Doron Zifrony                1 Oranim Str.          Tel: 972-3-5304324
Data General Technology      Givat Shmuel 51905     Fax: 972-3-5325917
                             Israel              E-Mail: doron@jaguar.dgt.co.il
Disclaimer: The opinions expressed hereby are my personal opinions.


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