Address translation mode

Home address space is where the work unit is dispatched. Primary address space indicates the segment tables used to fetch instruction is all address modes. Secondary address space indicates segment tables used to use to fetch data is the secondary ASC mode. 

ASC (access register address space control) mode determine how the processor resolve address in a program. 

In Primary ASC mode, processor does not use AR and fetch both instruction and data from the primary address space. 

In secondary ASC mode, processor does fetch instruction from the primary address space and data from the secondary address space. 

In AR ASC mode, processor uses AR to resolve address in address or data space. The program can move, compare and operate on data in other address space or data space.