Fortran manual for Xerox Computers

Lisp machines are general-purpose computers designed to efficiently run Lisp as their main software and programming language, usually via hardware support. They are an example of a high-level language computer architecture. In a sense, they were the first commercial single-user workstations. Despite being modest in number Lisp machines commercially pioneered many now-commonplace technologies, including windowing systems, computer mice, high-resolution bit-mapped raster graphics, computer graphic rendering, laser printing, networking innovations such as Chaosnet, and effective garbage collection. Several firms built and sold Lisp machines in the 1980s: Symbolics, Lisp Machines Incorporated, Texas Instruments, and Xerox. The operating systems were written in Lisp Machine Lisp, Interlisp (Xerox), and later partly in Common Lisp.

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The primary purpose of the Data statement is to give names to constants; instead of referring to pi as 3.141592653589793 at every appearance, the variable Pi can be given that value with a Data statement and used instead of the longer form of the constant. This also simplifies modifying the program, should the value of pi change.