loops), MVCL, which was introduced with the 1970 announcement of the System/370, and MVPG, patented and announced by IBM in 1989, each have advantages. ADMF ADMF (Asynchronous Data Mover Facility), which was introduced in 1992, goes beyond the capabilities of the MVPG (Move Page) instruction, which is limited to a single page, and can move groups of pages between Central and Expanded Storage. A macro instruction named IOSADMF, which has been described as an API that avoids "direct, low-level use of ADMF," can be used to read or write data to or from a hiperspace. Hiperspaces are created using DSPSERV CREATE. To provide reentrancy, IOSADMF is used together with a "List form" and "Execute form." z/Architecture operating systems The z/VSE Version 4, z/TPF Version 1 and z/VM Version 5 operating systems require z/Architecture. z/Architecture supports running multiple concurrent operating systems and applications even if they use different address sizes. This allows software developers to choose the address size that is most advantageous for their applications and data structures. On July 7, 2009, IBM on occasion of announcing a new version of one of its operating systems implicitly stated that Architecture Level Set 4 (ALS 4) exists, and is implemented on the System z10 and subsequent machines. The ALS 4 is also specified in LOADxx as ARCHLVL 3, whereas the earlier z900, z800, z990, z890, System z9 specified ARCHLVL 2. Earlier announcements of System z10 simply specified that it implements z/Architecture with some additions: 50+ new machine instructions, 1 MB page frames, and hardware decimal floating point unit (HDFU). Non-IBM implementations Platform Solutions Inc. (PSI) previously marketed Itanium-based servers which were compatible with z/Architecture. IBM bought PSI in July 2008, and the PSI systems are no longer available. FLEX-ES, zPDT and the Hercules emulator also implement z/Architecture. Hitachi mainframes running newer releases of the VOS3 operating system implement ESA/390 plus Hitachi-unique CPU instructions, including a few 64-bit instructions. While Hitachi formally collaborated with IBM on the z900-G2/z800 CPUs introduced in 2002, Hitachi's machines are not z/Architecture-compatible. Notes References Further reading Preshing on Programming - Atomic vs. Non-Atomic Operations Principles of Computer Design - Atomicity IBM mainframe technology Instruction set architectures Computer-related introductions in 2000 mainframe expanded storage 64-bit computers