The material in this book builds on the fundamentals of machine language programming as found in the book The Machine Language Book for the Commodore 64. In this book we will show you how to make use of many the Commodore 64's special features and capabilities using machine language.

The book is divided into three major sections. The first section concerns the internal representation of numbers on the Commodore 64 and describes in detail how the computer performs calculations and how its math routines can be used from machine language. In addition to the conversion of numbers between the various formats, the main emphasis of this section lies in writing arithmetic functions which can be used from BASIC with the help of the USR function.

The second section deals with a specialty of machine language: interrupts. After explaining some of the terms, interrupts are discussed in detail. Many sample programs illustrate the variety of uses for interrupt handling. At the close of this section, a machine language program demonstrates how BASIC subroutines can be controlled with interrupts.

The third and final section presents the concept of vectors in both the BASIC interpreter and kernal. The individual vectors are described and the procedure for adding your own commands is explained. The implementation of the REPEAT-UNTIL structure is used to demonstrate this.