[Oberon] 30th anniversary of Oberon

[rochus.keller at bluewin.ch]

@ Joerg Straube

Ok, thanks. 

>> The first Oberon system on Ceres 1 was programmed in Oberon 87.
>From that I conclude that Oberon 87 was actually used at least for two years and there was a release of an Oberon System which was officially written in Oberon 87. Thus Oberon 87 is not simply a theoretical approach, but an original, field-tested "product". From Nemo Nusquam we've heard that Oberon 87 continued to live at Ulm university.

>> The Oberon compiler (and Oberon system) evolved gradually to Oberon 90.
I see, but as far as I understand this gradual evolvment happend after the Oberon System on Ceres 1 (which was written in Oberon 87) was released. From the fact that Oberon 87 and 90 are not compatible I conclude that both versions exist for themselves, even if (unfortunatly) they have the same name. From my point of view it would have been justified and useful to distinguish the versions by name, as was done for example with Modula versus Modula-2, Algol 58 versus 60 versus 68, or Oberon versus Oberon-2. 
For my original question, this means that Oberon 90 can certainly be regarded as an individual achievement, which was officially published in 1990, and which therefore has its 30th anniversary in 2020. 
But since Oberon 87 and 90 were not distinguished by name, people will probably consider 1987 as the official Oberon publication date. For me, this is a satisfactory answer to the issue.

Best 
R.