Chapter 2 Programming Language Concepts R . Sebesta

Review question

6.What hardware capability that first appeared in the IBM 704 computer strongly affected the evolution of programming languages ? Explain why?

A:  The inclusion of floating-point hardware capability that first appeared in the IBM 704 computer strongly affected the evolution of programming languages because at that time ,the lack of floating-point hardware in the available computers. All floating –point operations had to be simulated in software, a very time-consuming process.

7. In what year was the Fortran design project begun ?

A: May 1954

8. What was the primary application area of computers at the time Fortran was designed ?

A: Mathematics applications

9. What was the source of all of the control flow statements of Fortran I ?

A: They were based on 704 instructions

10. What was the most significant feature added to Fortran I to get Fortran II ?

A: Independent-compilation capability

Problem Set

6. Make an educated guess as to the most common syntax error in LISP programs.

A: Undefined escape sequences in literal strings. The backslash character can be used in literal strings and characters :

       - to escape various characters
       - to introduce an escape sequence representing a character

7. LISP began as a pure functional language but gradually acquired more and more imperative features. Why ?

A:Because there is always a new idea for the uses and begin to develop the language.

8. Describe in detail the three most important reasons, in your opinion, why ALGOL 60 did not become a very widely used language. 

A:1.Excessive flexibility hurt ALGOL60 since languages that are difficult to learn were not as well received as languages with a more rigid structure. 2.Sebesta (2002, p. 60) notes that its association with BNF alienated the language as strange and complicated. If programmers are not excited about using a language, they will always find a different one. 3.perhaps the most important reason that ALGOL60 was not very widely used was because of a lack of support from IBM, who was at the time the preeminent company for using computer languages. 

9. Why, in your opinion, did COBOL allow long identifiers when Fortran and ALGOL did not ? 

A:COBOL is more of a reporting language than Fortran. Since Fortran handles calculations much better, there is not a real need for long identifiers. As a reporting language, COBOL uses long identifiers in tagging the source to the reports it is writing. Also, COBOL is the closest language to a fully, self documenting language, that it gets, and long identifiers provides one more case for i

10. Outline the major motivation of IBM in developing PL/I.

A:Like Fortran, PL/I was developed as an IBM product. By the early 1960s, the users of computers in industry had settled into two separate and quite different camps: scientific and business. From the IBM point of view, scientific programmers could use either the large-scale 7090 or the small-scale 1620 IBM computers. This group used floating-point data and arrays extensively

For business applications, people used the large 7080 or the small 1401 IBM computers. They needed the decimal and character string data types, as well as elaborate and efficient input and output facilities. They used COBOL, although in early 1963 when the PL/I story begins