Editing MVS (section)

==MVS/XA==
'''MVS/XA''', or '''Multiple Virtual Storage/Extended Architecture''', was a version of MVS that supported the [[System/370#Expanding the address space|370-XA]] architecture, which had a new I/O architecture and also expanded addresses from 24&nbsp;bits to 31&nbsp;bits, providing a 2&nbsp;[[gigabyte]] addressable memory area.<ref>{{Cite book | last1=Hoskins | first1=Jim | last2=Frank | first2=Bob | title=Exploring IBM eServer zSeries and S/390 Servers: See Why IBM's Redesigned Mainframe Computer Family Has Become More Popular than Ever! | year=2003 | publisher=Maximum Press (FL) | isbn=1-885068-91-3 | pages=210–290 | url=https://books.google.com/books?id=NtHhpIjIFMEC&q=computer+virtualization+%22virtual+machine%22+date:1960-2004&pg=PA33 }}</ref> MVS/XA supported a 24-bit legacy addressing mode for older 24-bit applications (i.e. those that stored a 24-bit address in the lower 24&nbsp;bits of a 32-bit word and utilized the upper 8&nbsp;bits of that word for other purposes).