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Programming Languages
The definition of the term programming language can vary with the context: these languages are both tools for directing the operation of a computer and tools for organizing and expressing solutions to problems. At the lowest level is pure binary code. This is so impractical to use that humans almost never use it, even though it is actually the only language that the machine "understands" and that does not need further translation. A step above is symbolic assembly language in which the names of variables and of operations are written in symbols. High level languages provide more convenient instructions; they also take over most storage-management tasks. Both of these attributes abstract away machine-level details to permit fuller attention to the problem to be solved. The first programming language that both deserves the name of a high level language and received broad acceptance due to efficient automatic compilation was FORTRAN. FORTRAN allowed programmers to express mathematical formulae in a notation that was very similar to the usual one. The first programming language with a compact and exact language definition, including a formal specification of the syntax, was Algol-60. The Algol-60 report could be regarded as the “birth certificate” of computer science. To illustrate the difference between assembly and high level languages, let’s take the example that we want to add the value of the variables x and y and assign the result to z. In a typical assembly language this would look like:
LOAD x, R0(Load the value of the variable x into the internal register R0)
LOAD y, R1(Load the value of the variable y into the internal register R1)
ADD R0,R1,R2 (Add the internal registers R0 and R1 and assign the result to R2)
STORE R2, z(Store the value of the internal register R2 into the variable z)
In Algol-60 we simply write: z := x + y (The rather unusual := stands for assign, or make equal to) It is obvious that the Algol code is not only much more compact and easier to read, it is also much less error prone. [Sources: Encyclopedia of Computer Science, Fourth Edition, Anthony Ralston, Edwin D. Reilly, David Hemmendinger; Laszlo Böszörmenyi: Notes to the Virtual Exhibition "People behind Informatics"]
 

 

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