Niklaus Emil Wirth is a Swiss computer scientist. He has designed several programming languages, including Pascal, pioneered several classic topics in software engineering. In 1984 he won the Turing Award recognized as the highest distinction in computer science, for developing a sequence of innovative computer languages. Wirth was born in Winterthur, Switzerland, in 1934. In 1959 he earned a degree in Electronics Engineering from the Swiss Federal Institute of Technology Zürich. In 1960 he earned an M. Sc. from Université Laval, Canada. In 1963 he was awarded a Ph. D. in Electrical Engineering and Computer Science from the University of California, supervised by the computer designer pioneer Harry Huskey. From 1963 to 1967 he served as assistant professor of Computer Science at Stanford University and again at the University of Zurich. In 1968 he became Professor of Informatics at ETH Zürich, taking two one-year sabbaticals at Xerox PARC in California. Wirth retired in 1999. In 2004, he was made a Fellow of the Computer History Museum "for seminal work in programming languages and algorithms, including Euler, Algol-W, Pascal and Oberon."
Wirth was the chief designer of the programming languages Euler, Algol W, Modula, Modula-2, Oberon-2, Oberon-07. He was a major part of the design and implementation team for the Lilith and Oberon operating systems, for the Lola digital hardware design and simulation system, he received the Association for Computing Machinery Turing Award for the development of these languages in 1984 and in 1994 he was inducted as a Fellow of the ACM. His book, written jointly with Kathleen Jensen, The Pascal User Manual and Report, served as the basis of many language implementation efforts in the 1970s and 1980s in the United States and across Europe, his article Program Development by Stepwise Refinement, about the teaching of programming, is considered to be a classic text in software engineering. In 1975 he wrote the book Algorithms + Data Structures = Programs. Major revisions of this book with the new title Algorithms + Data Structures were published in 1985 and 2004; the examples in the first edition were written in Pascal.
These were replaced in the editions with examples written in Modula-2 and Oberon respectively. His textbook, Systematic Programming: An Introduction, was considered a good source for students who wanted to do more than just coding. Regarded as a challenging text to work through, it was sought as imperative reading for those interested in numerical mathematics. In 1992 he published the full documentation of the Oberon OS.. A second book was intended as a programmer's guide. In 1995, he popularized the adage now known as Wirth's law, which states that software is getting slower more than hardware becomes faster. In his 1995 paper A Plea for Lean Software he attributes it to Martin Reiser. Asteroid 21655 Niklauswirth Extended Backus–Naur Form Wirth syntax notation Bucky bit Wirth–Weber precedence relationship List of pioneers in computer science Biography at ETH Zürich. Personal home page at ETH Zürich. Niklaus Wirth at DBLP Bibliography Server Niklaus E. Wirth at ACM. Wirth, Niklaus. "Program Development by Stepwise Refinement".
Communications of the ACM. 14: 221–7. Doi:10.1145/362575.362577. Wirth, N.. "On the Design of Programming Languages". Proc. IFIP Congress 74: 386–393. Turing Award Lecture, 1984 Pascal and its Successors paper by Niklaus Wirth – includes short biography. A Few Words with Niklaus Wirth The School of Niklaus Wirth: The Art of Simplicity, by László Böszörményi, Jürg Gutknecht, Gustav Pomberger. Dpunkt.verlag / Morgan Kaufmann Publishers, 2000. ISBN 3-932588-85-1 / ISBN 1-55860-723-4; the book Compiler Construction The book Algorithms and Data Structures The book Project Oberon – The Design of an Operating System and Compiler. The book about the Oberon language and Operating System is now available as a PDF file; the PDF file has an additional appendix Ten Years After: From Objects to Components. Project Oberon 2013
Switzerland the Swiss Confederation, is a country situated in western and southern Europe. It consists of 26 cantons, the city of Bern is the seat of the federal authorities; the sovereign state is a federal republic bordered by Italy to the south, France to the west, Germany to the north, Austria and Liechtenstein to the east. Switzerland is a landlocked country geographically divided between the Alps, the Swiss Plateau and the Jura, spanning a total area of 41,285 km2. While the Alps occupy the greater part of the territory, the Swiss population of 8.5 million people is concentrated on the plateau, where the largest cities are to be found: among them are the two global cities and economic centres Zürich and Geneva. The establishment of the Old Swiss Confederacy dates to the late medieval period, resulting from a series of military successes against Austria and Burgundy. Swiss independence from the Holy Roman Empire was formally recognized in the Peace of Westphalia in 1648; the country has a history of armed neutrality going back to the Reformation.
It pursues an active foreign policy and is involved in peace-building processes around the world. In addition to being the birthplace of the Red Cross, Switzerland is home to numerous international organisations, including the second largest UN office. On the European level, it is a founding member of the European Free Trade Association, but notably not part of the European Union, the European Economic Area or the Eurozone. However, it participates in the Schengen Area and the European Single Market through bilateral treaties. Spanning the intersection of Germanic and Romance Europe, Switzerland comprises four main linguistic and cultural regions: German, French and Romansh. Although the majority of the population are German-speaking, Swiss national identity is rooted in a common historical background, shared values such as federalism and direct democracy, Alpine symbolism. Due to its linguistic diversity, Switzerland is known by a variety of native names: Schweiz. On coins and stamps, the Latin name – shortened to "Helvetia" – is used instead of the four national languages.
Switzerland is one of the most developed countries in the world, with the highest nominal wealth per adult and the eighth-highest per capita gross domestic product according to the IMF. Switzerland ranks at or near the top globally in several metrics of national performance, including government transparency, civil liberties, quality of life, economic competitiveness and human development. Zürich and Basel have all three been ranked among the top ten cities in the world in terms of quality of life, with the first ranked second globally, according to Mercer in 2018; the English name Switzerland is a compound containing Switzer, an obsolete term for the Swiss, in use during the 16th to 19th centuries. The English adjective Swiss is a loan from French Suisse in use since the 16th century; the name Switzer is from the Alemannic Schwiizer, in origin an inhabitant of Schwyz and its associated territory, one of the Waldstätten cantons which formed the nucleus of the Old Swiss Confederacy. The Swiss began to adopt the name for themselves after the Swabian War of 1499, used alongside the term for "Confederates", used since the 14th century.
The data code for Switzerland, CH, is derived from Latin Confoederatio Helvetica. The toponym Schwyz itself was first attested in 972, as Old High German Suittes perhaps related to swedan ‘to burn’, referring to the area of forest, burned and cleared to build; the name was extended to the area dominated by the canton, after the Swabian War of 1499 came to be used for the entire Confederation. The Swiss German name of the country, Schwiiz, is homophonous to that of the canton and the settlement, but distinguished by the use of the definite article; the Latin name Confoederatio Helvetica was neologized and introduced after the formation of the federal state in 1848, harking back to the Napoleonic Helvetic Republic, appearing on coins from 1879, inscribed on the Federal Palace in 1902 and after 1948 used in the official seal.. Helvetica is derived from the Helvetii, a Gaulish tribe living on the Swiss plateau before the Roman era. Helvetia appears as a national personification of the Swiss confederacy in the 17th century with a 1672 play by Johann Caspar Weissenbach.
Switzerland has existed as a state in its present form since the adoption of the Swiss Federal Constitution in 1848. The precursors of Switzerland established a protective alliance at the end of the 13th century, forming a loose confederation of states which persisted for centuries; the oldest traces of hominid existence in Switzerland date back about 150,000 years. The oldest known farming settlements in Switzerland, which were found at Gächlingen, have been dated to around 5300 BC; the earliest known cultural tribes of the area were members of the Hallstatt and La Tène cultures, named after the archaeological site of La Tène on the north side of Lake Neuchâtel. La Tène culture developed and flourished during the late Iron Age from around 450 BC under some influence from the Gree
The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. In total, around 600,000 PDP-11s of all models were sold, making it one of DEC's most successful product lines; the PDP-11 is considered by some experts to be the most popular minicomputer ever. The PDP-11 included a number of innovative features in its instruction set and additional general-purpose registers that made it much easier to program than earlier models in the series. Additionally, the innovative Unibus system allowed external devices to be interfaced to the system using direct memory access, opening the system to a wide variety of peripherals; the PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years. But the ease of programming of the PDP-11 made it popular for general purpose computing uses as well; the design of the PDP-11 inspired the design of late-1970s microprocessors including the Intel x86 and the Motorola 68000.
Design features of PDP-11 operating systems, as well as other operating systems from Digital Equipment, influenced the design of other operating systems such as CP/M and hence MS-DOS. The first named version of Unix ran on the PDP-11/20 in 1970, it is stated that the C programming language took advantage of several low-level PDP-11–dependent programming features, albeit not by design. An effort to expand the PDP-11 from 16 to 32-bit addressing led to the VAX-11 design, which took part of its name from the PDP-11. In 1963, DEC introduced what is considered to be the first commercial minicomputer in the form of the PDP-5; this was a 12-bit design adapted from the 1962 LINC machine, intended to be used in a lab setting. DEC simplified the LINC system and instruction set, aiming the PDP-5 at smaller settings that did not need the power of their larger 18-bit PDP-4; the PDP-5 was a success selling about 50,000 examples. During this period, the computer market was moving from computer word lengths based on units of 6-bits to units of 8-bits, following the introduction of the 7-bit ASCII standard.
In 1967–68, DEC engineers designed a 16-bit machine, the PDP-X, but management cancelled the project. Several of the engineers from the PDP-X formed Data General; the next year they introduced the 16-bit Data General Nova. The Nova was a major success, selling tens of thousands of units and launching what would become one of DEC's major competitors through the 1970s and 80s. A subsequent effort, code-named "Desk Calculator", looked at a variety of options before choosing what became the 16-bit PDP-11. DEC sold over 170,000 PDP-11s in the 1970s. Manufactured of small-scale transistor–transistor logic, a single-board large scale integration version of the processor was developed in 1975. A two-or-three-chip processor, the J-11 was developed in 1979; the last models of the PDP-11 line were the PDP-11/94 and -11/93 introduced in 1990. The PDP-11 processor architecture has a orthogonal instruction set. For example, instead of instructions such as load and store, the PDP-11 has a move instruction for which either operand can be memory or register.
There are output instructions. More complex instructions such as add can have memory, input, or output as source or destination. Most operands can apply any of eight addressing modes to eight registers; the addressing modes provide register, absolute, relative and indexed addressing, can specify autoincrementation and autodecrementation of a register by one or two. Use of relative addressing lets a machine-language program be position-independent. Early models of the PDP-11 had no dedicated bus for input/output, but only a system bus called the Unibus, as input and output devices were mapped to memory addresses. An input/output device determined the memory addresses to which it would respond, specified its own interrupt vector and interrupt priority; this flexible framework provided by the processor architecture made it unusually easy to invent new bus devices, including devices to control hardware that had not been contemplated when the processor was designed. DEC published the basic Unibus specifications offering prototyping bus interface circuit boards, encouraging customers to develop their own Unibus-compatible hardware.
The Unibus made the PDP-11 suitable for custom peripherals. One of the predecessors of Alcatel-Lucent, the Bell Telephone Manufacturing Company, developed the BTMC DPS-1500 packet-switching network and used PDP-11s in the regional and national network management system, with the Unibus directly connected to the DPS-1500 hardware. Higher-performance members of the PDP-11 family, starting with the PDP-11/45 Unibus and 11/83 Q-bus systems, departed from the single-bus approach. Instead, memory was interfaced by dedicated circuitry and space in the CPU cabinet, while the Unibus continued to be used for I/O only. In the PDP-11/70, this was taken a step further, with the addition of a dedicated interface between disks and tapes and memory, via the Massbus. Although input/output devices continued to be mapped into memory addresses, some additional programming was necessary to set up the added bus interfaces; the PDP-11 supports hardware interrupts at four priority levels. Interrupts are serviced by software service routines, which could specify