This document is one of several documents containing the Implementation Specification of Europay's Open Terminal Architecture. Other volumes in this series specify the Forth and C language programming interfaces, as well as the EMV application library and the Terminal Kernel Test Program (see related publications).

The overall architecture of the Open Terminal Architecture is described in Appendix F, “System Architecture,” and is based on a Virtual Machine (VM) that can be programmed using high-level languages such as Forth or C. For compactness and efficiency a tokenised form has been developed for delivering compiled programs to terminals of all CPU types. This and other Virtual Machine related issues are explained in Section 3.

This International Standard describes a set of functions to be implemented in terminals in terms of instructions for a Virtual Machine. With these functions the application programmer is able to generate application software that is compact, portable and certifiable on all OTA terminals.

The inclusion of a function is determined by three main criteria:

• core compactness,
• execution speed,
• security requirements.

This International Standard provides the specifications for the standard OTA kernel in several layers:

• definition of the Virtual Machine (VM) (Section 3);
• description of the services provided by the VM to terminal programmers (Section 4);
• specification of a set of tokens representing the native machine language of the VM (Section 5);
• specification of the format in which token modules are delivered to an OTA kernel for processing (Section 6).