Introduction to Computer Programming

Compilation Process

• A compiler translates a high-level program to machine-specific assembler language, which is then converted to machine code by an assembler.
• Compiled code is usually faster than interpreted code, but requires compilation-time.

Interpreted Code

• An interpreter translates a high-level program on-the-fly, executing the necessary set of low-level operations.
• Interpreted code avoids the overhead of compilation-time, making it suitable for rapid implementation and testing.
• Examples of interpreted code languages include Matlab and Python.

Virtual Machine

• A virtual machine behaves as an abstract-machine layer on top of a real machine.
• A high-level program is compiled to a special byte-code, which is then interpreted by the virtual machine program.
• Interpreting byte-code is usually faster than interpreting high-level code directly.
• Examples of virtual machines include the Java virtual machine.

Advantages of Representations

• Compiled code is typically fastest.
• Interpreted code is highly portable and quick to implement and test.
• Virtual machines offer a combination of speed and portability.

High-Level Language

• The primary purpose of a high-level language is to permit more direct expression of a programmer's design.
• High-level code modules can be designed to "plug" together piece-by-piece, allowing large programs to be built out of small, comprehensible parts.

Machine Language

• The native language of a computer is binary—ones and zeros.
• Machine language is called native binary code.
• Developing correct programs in machine language is tedious and complex, and practical only for very small programs.

Assembly Language

• Assembly languages have simple mnemonic instructions that directly map to a sequence of machine language operations.
• Programs written in assembly language are translated to machine code using an assembler program.
• Assembly languages are low-level and unsuited to large-scale programming.
• Assembly language programs tend to be non-portable, requiring rewriting to run on a different machine.

High-Level Languages

• High-level languages, such as Fortran and Algol, were introduced in the 1950s and 60s.
• These languages provide mechanisms, such as subroutines and conditional looping constructs, which enhance the structure of a program.
• High-level languages are an abstraction of the underlying machine instructions and are not tied to any particular hardware.
• Ideally, a program written in a high-level language can be ported to a different machine and run without change.

Learn about the native language of computers, machine language, and how early digital computers were programmed using binary and hexadecimal codes.