The IA32 Architecture is specified by the following documents
Intel Architecture Software Developer's Manual, Volume 1: Basic Architecture
Intel Architecture Software Developer's Manual, Volume 2: Instruction Set Reference Manual
Intel Architecture Software Developer's Manual, Volume 3: System Programming Guide
Only the features of the Intel486 processor instruction set may be assumed to be present. An application is responsible for determining if any additional instruction set features are available before using those additional features. If a feature is not present, then the application may not use it.
Applications conforming to this specification must provide feedback to the user if a feature that is required for correct execution of the application is not present. Applications conforming to this specification should attempt to execute in a diminished capacity if a required instruction set feature is not present.
This specfication does not provide any performance guarantees of a conforming system. A system conforming to this specification may be implemented in either hardware or software.