The Complete Spectrum ROM Disassembly

The Complete Spectrum ROM Disassembly

The Sinclair Spectrum is a complex microcomputer whose normal operation is controlled by the 16K ROM program that is inside every Spectrum. In this book, Dr. Ian Logan and Dr. Frank O'Hara examine this program and explain exactly what it is that makes the Spectrum operate in the way that it does. Every routine in the ROM has been disassembled and has full comments on what its function is and how it relates to the other functions in the ROM. Each aspect of the Spectrum operation is discussed in detail: The input/output routines: These cover the keyboard routines, the loudspeaker, the cassette handling routines, and the screen and printer handling routines. BASIC line and command interpretation: This part of the ROM considers each BASIC statement as a set of commands. For each command there is a command routine and it is the execution of the machine code in the appropriate command routine that affects the interpretation. Expresion evaluation: The Spectrum has a most comprehensive expression evaluator allowing for a wide range of variable types, functions and operators. The arithemetic routines and the floating point calculator: This part of the ROM handles all the numbers in a unique five byte floating point form, as well as all the mathematical functions. Overall, the 16K ROM program offers an extremely wide range of BASIC commands and functions. This book makes all the functions and entry points available for use in your own programs or for modification into your own special routines. The Complete Spectrum ROM Disassembly is a must for all serious programmers of the Spectrum.