impact of ucsd pascal a view from the trenches
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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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before the flood
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
rise of the microcomputer
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
pascal as a new language
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
key features of pascal
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…
limitations
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!
in the meantime the revenge of the phone company tpc
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!)
pascal is dead its legacy lives on
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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