Chapter 2

• Statements like V1 = V2 => R1. This means: Compare the variables V1 and V2: If they are identical then assign the value true to R1, otherwise assign the value false. Such operations could also be applied on complicated data structures.
• Programming plans, calling sub-programs, and different stop criteria.
• Conditional statements (but no ELSE statement).
• Repetition of statements (loops).
• Operations of predicate logic and Boolean algebra.
• Powerful operations on lists and pairs of lists.
• No recursion.
• Data types like: floating point, fixed point, complex numbers.
• Arrays, records, hierarchical data structures, list of pairs.
• Arithmetic exception handling.
• Applications to play chess are described on more than 60 pages.
• Assertion(6) as was subsequently used in the EIFFEL and MODULA-2 languages.
• Complicated expressions with parentheses and nesting.

Short Code (1949)

• John Mauchly created a code called Short Code. It was still fairly cryptic, but it allowed equations to be entered using a special code.
• This new code inspired a woman named Grace Murray Hopper.

Univac and Eniac (1945)

• The first fully functioning electronic digital computer to be built in the U.S. was ENIAC, constructed at the Moore School of Electrical Engineering, University of Pennsylvania, for the Army Ordnance Department, by J. Presper Eckert and John Mauchly.
• In 1944, John von Neumann joined the ENIAC group
  • He had become 'intrigued' (Goldstine's word) with Turing's universal machine while Turing was at Princeton University during 1936-1938.
  • von Neumann emphasised the importance of the stored-program concept for electronic computing, including the possibility of allowing the machine to modify its own program in useful ways while running (for example, in order to control loops and branching).
• UNIVAC, 1951, Eckert-Mauchly Computer Corporation, Philadelphia (the first computer to be available commercially in the U.S.)

IBM 704 (1954) - Fortran

• IBM 704
• IBM 704 manual

• "I really didn't know what the hell I wanted to do with my life...I said no, I couldn't. I looked sloppy and disheveled. But she insisted and so I did. I took a test and did OK." - John Backus on interviewing for IBM.

• John Backus wanted a programming language closer to human language, which is the definition of a high level language.
• The first computer to run the first compiler was the IBM 704, which John Backus helped design.
• Prior to Fortran all floating point operations had to be simulated in software, a very time consuming process. (Look for an assignment on this).
• The compiler was introduced in April 1957, Fortran I.
  • Input/output formatting
  • variable names up to six characters long (two chars prior to this)
  • user defined sub-routines
  • If
    • if(arithmetic expresion) N1, N2, N3
  • Do loop
    • Do N1 variable = first_value, last_value
  • No data typing. Variables whose names began with I,J,K,L,M, and N were ints; all others were floats
  • Since no dynamic allocation of memory was allowed there was no recursion and no data types could grow.
  • Original plans were never to have Fortran run on anything but IBM, yet today all languages owe a debt to fortran.
  • Programming manual
  
  

• LISP

  
  

• ALGOL 60

  • Dynamic Arrays - one for which the subscript range is specified by variables so that the size of the array is set at the time storage is allocated.
  • Reserved Words - the symbols used for keywords are not allowed to be used as identifiers by the programmer.
  • User defined data types - allow the user to design data abstractions that fit particular problems very closely.
  • BNF (Baucus-Naur form)
    

    		 ::=   
    
     		 ::=  |  "."
    
     		 ::=   [] 
    	      		 |  
    
     		 ::= []   
    
     		 ::=  ","   
    

  • An Algol program that calcuates the mean
  
  

• COBOL

  • Not covered
  
  

• BASIC

  • Not covered

• PL/1

  • Not covered

• SNOBOL

  • Covered

• APL

  • Not covered

• ALGOL 68

  • Not covered

• PROLOG

  • Covered

• Ada

  • Histories largest design effort.
  • DoD
  • 1974 - half computer systems in DoD were embedded systems
  • 450 different languages were being used.
  • No standards
  • So in 1974 they proposed the development of a single high-level language for embedded systems.
  • HOLWG - the group
  • All four proposals were based on Pascal.
  • 1979 the one chosen was the only foreign competitor in the bunch.
  • They named it Ada
  • Language Overview
    • Encapsulation
    • Data Abstraction
    • Program units can be generic in Ada. (reusable)
    • It was cosidered a huge set of language features at the time
    • The compiler was much harder to develop than they thought, it took until 1985.
    
    

  • Smalltalk

    • Not covered

  • C++

    • Covered

  • java

    • Covered

  • Scripting languages

  • C#