1. Introduction and Overview of the Course CS 480/680 – Comparative Languages

2. Introduction and Overview2 What is this class about?  By studying several programming languages, we will learn: What different types of languages have in common, and what differs  Paradigms How programming language features are implemented How to pick up new programming languages quickly

3. Introduction and Overview3 Course Overview 1.Introduction to Programming Languages a.Groups of Languages b.Implementation of programming concepts c.Formal specification of languages 2.Two Example Languages a.Ruby – A very object-oriented language b.Scheme – A functional programming language 3.Student Presentations of Languages

4. Introduction and Overview4 Programming Language Groups  Level  Historical  Paradigm  Interpreted/Compiled/Partially-compiled

5. Introduction and Overview5 Machine Code  The lowest level “language”  Not designed to be human readable  An instruction consists of an opcode word, followed by extension words  Directly operate the gates/hardware of the CPU 0xD64A 1101 0110 0010 1010 Place the value zero into register D2.

6. Introduction and Overview6 Low Level Languages  In the beginning there was assembly language Requires an understanding of the CPU hardware Instructions directly control the registers, gates, and devices in the CPU MAINMOVE.W#20,D3 ADD.W$2002,D3 MOVE.W$2000,D4 DIVS.WD3,D4 BGEREADLOOP One line of assembly language corresponds to one machine code instruction.

7. Introduction and Overview7 Assembly Pros and Cons  Advantages Fast, efficient code Direct control of the hardware  Disadvantages Different hardware requires a completely different program (not just a port)  Requires knowledge of the hardware Many instructions to do simple operations Code is difficult to read and understand

8. Introduction and Overview8 Compiled Languages  Assembly is a low level language  High level languages include C, C++, Pascal, FORTRAN, and many others  Source code is just ASCII text  Compiled into executable format Machine code with some special tags to tell where to load into memory