1	Make it as simple as possible, but not simpler: The Programming Language Oberon Niklaus Wirth Oberon Day CERN, 10.3.2004
2	Part 1: Historical perspective
3	Design of Pascal, 1968-70 Algol-like phrase structure (syntax) Generality of expressions Conditions and the type Boolean Procedures and functions, recursion The concept of locality (block structure) Data structures: Array, Record, Set, File, Pointer
4	Pascal designed with three primary goals: - A tool for decent teaching - A tool for designing system software (compilers, operating systems) - Compactness and efficiency
5	Design of Modula-2 1977-1979 Pascal as basis Additional standard data types Modules, interfaces, information hiding, separate compilation Elements for parallel programming
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8	Design of Oberon 1986-1988 Modula-2 as basis Discarding several inessential features Adding type extensibility (inheritance) Simplify syntax
9	Complexity of syntax of programming languages
10	Part 2: The benefits of simplicity, or the curse of complexity Economy of design Simpler to define and document Easier to learn and understand Less difficult to implement, more efficient compilation Fewer misunderstandings, more efficient programs Disciplined programming, fewer mistakes
11	Conclusions and questions All together increases efficiency of program development, program maintenance, and program execution. The more complex the task, the more perspicuous and reliable must be the tools If problem is complex, do not add further, home-made complexity through tools Can a simple language be powerful? Can flexibility be achieved without sacrificing efficiency (or vice versa)?
12	Part 3: Oberon for embedded systems System engineers want to have close control over program and code No hidden mechanisms tolerated Oberon compiler generates “straight” code Predictable behavior, no surprises Ideal for light-weight systems with or without underlying “operating system” Modules with separate compilation
13	"Oberon allows to program device..." Oberon allows to program device drivers through its “low-level features”, which are encapsulated within specific modules. Directs access to device interface registers. No overhead through crossing of module boundaries. Watertight type checking, also across module boundaries, at compile time! Very fast loading and linking. Fast, dynamic loading of modules upon demand at run-time. Compiler was designed/ported for Strong-ARM within a month.
14	Simplicity and Complexity Самый верный признак истины -- это простота и ясность. Ложь всегда бывает сложна, вычурна и многословна. Лев Николаевич Толстой The most reliable sign of truth is simplicity and clarity. Lie is invariably complicated, gaudy and verbose.