underlying hardware, which changed significantly throughout the life of the AS/400 platform. Features include a RDBMS (Db2 for i), a menu-driven interface, support for multiple users, block-oriented terminal support (IBM 5250), and printers. Object-based design Unlike the "everything is a file" feature of Unix and its derivatives, on IBM i everything is an object (with built-in persistence and garbage collection). Single-level store IBM uses a single-level store virtual memory architecture in the AS/400 platform. For 64-bit PowerPC processors, the virtual address resides in the rightmost 64 bits of a pointer while it was 48 bits in the S/38 and CISC AS/400. The 64-bit address space references main memory and disk as a single address set which is the single-level store concept. Hardware integration Later generations of hardware are also capable of supporting various guest operating systems, including SSP, AIX, Linux, Microsoft Windows 2000 and Windows Server 2003. While OS/400, AIX, and Linux are supported on the POWER processors on LPARs (logical partitions), Windows is supported with either single-processor internal blade servers (IXS) or externally linked multiple-processor servers (IXA and iSCSI). SSP guests were supported using emulation from OS/400 V3R6 through V4R4 using the Advanced 36 Machine facility of the operating system, a feature distinct from the System/36 Environment compatibility layer which requires System/36 software to be recompiled. Hardware CPUs System models See also Notes References External links IBM's Power Systems product page IBM Archives: A Brief History of the IBM AS/400 and iSeries The IBM AS400 A technical introduction AS/400 System i Computer-related introductions in 1988 48-bit computers 64-bit computers