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Impact of UCSD Pascal A View from the Trenches

Impact of UCSD Pascal A View from the Trenches. Roger Sumner. Before The Flood. Languages of the day: Fortran, COBOL, PL/I, RPG(!) Batch Mainframe Computers Punch cards, line printers, reel-to-reel tapes, overnight batch runs HUGELY EXPENSIVE

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Impact of UCSD Pascal A View from the Trenches

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  1. Impact of UCSD PascalA View from the Trenches Roger Sumner

  2. Before The Flood • Languages of the day: Fortran, COBOL, PL/I, RPG(!) • Batch Mainframe Computers • Punch cards, line printers, reel-to-reel tapes, overnight batch runs • HUGELY EXPENSIVE • Minicomputers: Data General, DEC PDP-10, PDP-11, early Prime

  3. Rise of the Microcomputer • Assembly language • Basic (many dialects) • PL/M (Digital Research, Intel) • All limited to specific platforms • Very difficult to use • Open need: portable, easy to use, powerful language + compiler + system

  4. Pascal As A New Language • Other academic/niche languages: Simula, Euler, APL, Lisp, Algol; all on mainframes • Pascal was an academic language, too, but… • Simple enough for a modest-sized compiler • Powerful enough to write a compiler! • Pointers as a full-fledged data type • Enabled recursive data structures

  5. Key Features of Pascal • Strong type checking - parameters & expressions • Pointer types • Safe, coupled to specific types (unlike “C” at the time) • Allows easily expressed recursive data structures • Very easy to like! • Structured programming wasn’t common in those days • UCSD Pascal popularized Pascal itself, which was then picked up by… • Microsoft Pascal • Borland Turbo Pascal • Apple Pascal (32-bit) • Adopted as a standard development language by many organizations, but…

  6. Limitations! • What Brian Kernighan saw as missing: • Strings, variable size arrays, logical ops • Separate compilation, libraries • Flexible I/O • An “escape” from compiler builtins & dogma • Lots of folks modified Pascal to solve these issues • Raising the ire of the theologians • But you gotta get your work done!

  7. In the meantime… The revenge of The Phone Company (TPC) • C started its march towards domination • Low-level strings (OK with libraries) • Very flexible separate compilation (dangers, too!) • Pointers to functions • Very flexible I/O mechanism • Pointer/array semantics more powerful, but more dangerous • Lear Jet versus Piper Cub? (not in 1974!)

  8. Pascal is dead, its Legacy lives on • Pascal has gone the way of Latin • Borland Delphi = Pascal++ without credit • Key concepts live on, especially Java VM • Portable virtual machine • Friendlier, safer language than “C” • Strong type checking, scientific approach to program architecture

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