Processor Architecture

The ESA/390 Architecture is specified by the following documents:

• LINUX for S/390 ELF Application Binary Interface Supplement

• Enterprise Systems Architecture/390 Principles of Operation

Only the features of ESA/390 processor instruction set and the following optional instructions may be assumed to be present:

• additional floating point facility

• compare and move extended facility

• immediate and relative instruction facility

• string instruction facility

• square-root facility

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.