Storage access authorization controls in a computer system using dynamic translation of large addresses

A method of using the DAT mechanism in a computer processor to extend both: 1) the native storage access authorization architecture of the processor, and 2) to enable the processor to execute programs designed to operate under different storage access architectures. An executing program (called a source program) uses "source effective addresses" (source EAs) for locating its instructions and storage operands while executing on the processor (called the target processor).