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z/Architecture

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z/Architecture, initially and briefly called ESA Modal Extensions (ESAME), is IBM's 64-bit complex instruction set computer (CISC) instruction set architecture, implemented by its mainframe computers. IBM introduced its first z/Architecture-based system, the z900, in late 2000. Subsequent z/Architecture systems include the IBM z800, z990, z890, System z9, System z10, zEnterprise 196, zEnterprise 114, zEC12, zBC12, z13, z14, z15, z16, and z17.

Wikidata facts

Follows
IBM S/390
Said to be same as
IBM Z

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~88 min read

Encyclopedic overview

39 sections
Contents
  • Features
  • Extended-immediate facility
  • General-instructions-extension facility
  • High-word facility
  • Long-displacement facility
  • Miscellaneous-instruction-extensions Facility 1
  • Miscellaneous-instruction-extensions Facility 2
  • Miscellaneous-instruction-extensions Facility 3
  • Vector facility
  • Neural-network-processing-assist facility
  • Registers
  • Access registers
  • Breaking-event-address register (BEAR)
  • Control registers
  • Floating-point Control (FPC) register
  • Floating-point registers
  • General registers
  • Prefix register
  • Program status word (PSW)
  • Vector registers
  • Memory
  • Addressing
  • Types of main storage addresses
  • Address encoding
  • Addressing modes
  • Translation modes
  • Operating system support
  • z/OS
  • Code (or mixed) spaces
  • Data-only spaces
  • {{anchor}}Dataspaces and hiperspaces
  • IBM mainframe expanded storage
  • MVPG and ADMF
  • MVPG
  • ADMF
  • Non-IBM implementations
  • Notes
  • References
  • Further reading

z/Architecture, initially and briefly called ESA Modal Extensions (ESAME), is IBM's 64-bit complex instruction set computer (CISC) instruction set architecture, implemented by its mainframe computers. IBM introduced its first z/Architecture-based system, the z900, in late 2000. Subsequent z/Architecture systems include the IBM z800, z990, z890, System z9, System z10, zEnterprise 196, zEnterprise 114, zEC12, zBC12, z13, z14, z15, z16, and z17.

z/Architecture retains backward compatibility with previous 32-bit-data/31-bit-addressing architecture ESA/390 and its predecessors back to the 32-bit-data/24-bit-addressing System/360. The IBM z13 is the last z Systems server to support running an operating system in ESA/390 architecture mode. However, all 24-bit and 31-bit problem-state application programs originally written to run on the ESA/390 architecture will be unaffected by this change.

Excerpted from Wikipedia’s “z/Architecture” article, available under the CC BY-SA 4.0 licence.

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