Notes: Wednesday 18 January 2002

Schedule

• Sunday, 20 January: There will be staffed lab hours in the Olsson 001 lab, 7pm-10pm
• Sunday, 20 January: By Sunday, you should have at least read SICP, p. 1-21, read through the whole problem set, and answered questions 1-4.
• Monday, 21 January: No Class - Martin Luther King Day University Holiday.
• (Optional) Wednesday, 23 January: Radhika Nagpal Seminar, Olsson 009, 3:30pm: Programming using Origami Paper Folding
• Friday, 25 January: Problem Set 1

Everyone in the class should have received an email with your PS1 groups (sent out at 6:30pm yesterday).

Notes and Questions

What is a formal system?

What is the difference between a formal system and a language?

Languages are made of:

• Primitives (almost all languages have these) - the simplest surface forms with meaning
• Means of Combination (all languages have these) - rules of production (ways to make new surface forms from ones you already have)
• Means of Abstraction (all powerful languages have these) - ways to use simple surface forms to represent complicated ones

When learning a foreign language, which of primitives, means of combination or means of abstraction is hardest to learn?

Who was Admiral Grace Hopper and what did she do?

Compiler: A program that translates between two languages, usually from a high-level programming language to machine code.

What is the difference between a compiler and an interpreter?

Why did John Backus want a precise way of describing languages?

Links

• ENIAC Story (like most ENIAC histories, it is wrong about ENIAC being the "world's first electronic digital computer" — we'll learn why before PS4)
• ENIAC Programmer's Manual
• USS Hopper (Navy ship named after Admiral Grace Hopper, their slogan is "Dare and Do")
• John Backus biography

  
  

  Frankly, we didn't have the vaguest idea how the things would work out in detail... We struck out simply to optimze the object program, the running time, because most people at that time believed you really couldn't do that kind of thing.
  John Backus (on FORTRAN language and compiler, quoted in 1966)

University of Virginia Department of Computer Science CS 200: Computer Science

David Evans evans@virginia.edu Using these Materials