Note: this material was prepared by Prof. Gerhard Goos and formed the basis for a speech after a dinner to celebrate 25 years of WG2.4. We are indebted to Prof. Goos for assembling this fascinating and often amusing collection of facts from the group's archives.

In August 1973, IFIP TC 2 sponsored a Working Conference on Machine-Oriented Higher-Level Languages (MOHLLs) in Trondheim, Norway. It was organized by Knut Skog, professor at Tromso University. At that conference a resolution recommending the establishment of a Working Group on MOHLLs was passed without dissent. The establishment of WG2.4 was approved by TC2 and the IFIP General Assembly at their October 1973 meetings.

As background, the following may be recalled: These were the times of languages such as PL\360 (N. Wirth) and PLS (shortly afterwards, IBM) which combined high-level control structure with assembly-like features at the data level. Extensible languages and wide-spectrum languages were another trail which was explored. Macro-languages such as Waite's STAGE2 were in widespread use for addressing the severe portability issues amongst the multitude of different processor- and computer-architectures. BCPL (Martin Richards) and LIS (Ichbiah, a predecessor of Ada) were just in the making.

First Meeting at La Grande Motte

The Group held its first meeting at La Grande Motte, France on May 7-9, 1974 with W.A. Wulf as acting chairman and J. Horning as acting secretary. Here is a list of some of the people present (excerpted from the minutes; I am sure there were more people but they did not make it into the minutes): Peck (representing TC 2), Bell, Birkenbihl, Boom, Brown, Correll, P. Cousot, DeRemer, Goldsack, Goos, Griffiths, Haentgens, Heliard, Holager, Horning, Ichbiah, Koster, Krieg, Kronental, Krueger, Kruseman, Lagally, Lindsay, McKeag, Napper, Newey, Rain, Rissen, Ross, Russell, Scheidig, Schuman, Shaap, Skog, Trilling, Vanberne, van der Poel, Wichmann, Wickström, Wulf.

At the end of this meeting a subgroup of those present met and proposed an initial membership of WG2.4 based on the presentations and discussions of the meeting. This list was later amended and resulted in the initial membership: Correll, Cousot, Goos, Griffiths, Holager, Horning, Ichbiah, Kakehi, Koster, Rain, Richards, Ross, Schuman, Skog, van der Poel, Voda, Waite, Wichmann, Wulf.

The group proposed to publish an informal "MOL-Bulletin" patterned after the then famous "ALGOL-Bulletin" of WG2.1. This bulletin had Mark Rain, Mike Griffiths and then Patrick Cousot as its first editors and for several years a subscriber list of 400-600 people; the bulletin died in early 1980. The group also planned immediately its next working conference for 1976. It actually took place at Novosibirsk in 1977 with the title "Conference on Constructing Quality Software".

Here are some statements and titles from the minutes. (Aren't they still interesting?)

  • Horning's problem statement for WG2.4: We are concerned with languages oriented to applications where efficiency is a major concern and/or system integration and maintenance are likely to be significant problems.
  • Ichbiah coined the name System Implementation Languages (SILs) for the group, complaining that MOHLL is an anachronism. The switch of names took place in 1978.
  • Wulf: Have you ever tried to maintain two copies of a large system? It's impossible!
  • Ichbiah: I would like to say a firm no to a new language as a WG2.4 project. It would quickly produce sterility.

Here is a selected list of titles of presentations:

  • Horning: Designing MOLs and SILs for Reliability.
  • DeRemer: A Conceptual Framework for Object Definitions in Programming Languages.
  • Ross: Object-Oriented Features of a New Implementation Language.
  • Holager: Practical Experience with MARY.
  • Goos: Program Modules in Programming Languages.
  • Ichbiah: Visibility and Separate Compilation.
  • Schuman: Toward Modular Programming in High-Level Languages.
  • Scheidig: Recent Developments Concerning Wide Spectrum Languages.
  • Brown: Portable Software Using a High Level Macro Language.

Second Meeting at Berlin

The second meeting took place in Berlin, December 3-6, 1974 and was hosted by Kees Koster, then professor at the Technical University of Berlin. Brian Wichmann was secretary. The minutes say that three students, F. Denert, S. Jähnichen, and S. Dehottay assisted in preparing the notes.

This meeting saw amongst others presentations by DeRemer on Programming-in-the-large versus programming-in-the-small and by Liskov on A note on CLU.

The business meeting created the three meeting rule: An observer must be considered for membership after attending three meetings (proposal by Waite).

Third Meeting at Santa Cruz

The third meeting took place at Santa Cruz, May 28 - June 2, 1975, hosted by Frank DeRemer. This meeting had so much material to present and to discuss that we even split and held parallel discussion sessions.

Topics included user needs, SILs in industry vs. academia, special SILs: BCPL, CORAL 66, FORTRAN (!), BLISS, CLU, LIS, typing problems in SILs, compilation structures, and variables in programming languages.

In summary the minutes of this meeting list already most of the topics which later played a role in the development of Ada.

Further Meetings and Remarks

These initial meetings where followed by a steady series of meetings. The announcement of the Ada project appears first in the minutes of the fourth meeting held at St. Pierre de Chartreuse (near Grenoble), February 1976.

The fifth and the seventh meeting at Nottingham 1976 and Enschede 1978 were the really large Ada preparation meetings. The first one discussed requirements. The second one saw presentations and discussions of all four language proposals which then were named Blue, Green, Red and Yellow.

You can find an overview over all meetings here.

The notice "not for publication or quotation" appears first in the minutes of the Brussels meeting 1980. Niklaus Wirth had taken sentences out of context from the previous minutes and published them.