Machine environment which ran System/36 SSP applications in emulation. IBM often uses different names for the TIMI, SLIC and XPF in documentation and marketing materials, for example, the IBM i 7.4 documentation refers to them as the IBM i Machine Interface, IBM i Licensed Internal Code and IBM i Operating System respectively. TIMI The TIMI isolates users and applications from the underlying hardware. This isolation is more thorough than the hardware abstractions of other operating systems, and includes abstracting the instruction set architecture of the processor, the size of the address space and the specifics of I/O and persistence. This is accomplished through two interrelated mechanisms: Compilers for IBM i do not generate native machine code directly, instead they generate a high level intermediate representation defined by the TIMI. When a program is run, the operating system carries out ahead-of-time translation of the TIMI instructions into native machine code for the processor, and stores the generated machine code for future execution of the program. If the translation process changes, or a different CPU instruction set is adopted, the operating system can transparently regenerate the machine code from the TIMI instructions without needing to recompile from source code. Instead of operating on memory addresses, TIMI instructions operate on objects. All data in IBM i, such as data files, source code, programs and regions of allocated memory, are encapsulated inside objects managed by the operating system (c.f. the "Everything is a file" model in Unix). IBM i objects have a fixed type, which defines the set of applicable operations which may be carried out on them (for example, a Program object can be executed, but cannot be edited). The object model hides whether data is stored in primary, or secondary storage. Instead, the operating system automatically handles the process of retrieving and then storing the changes to permanent storage. The hardware isolation provided by the TIMI allowed IBM to replace the AS/400's 48-bit IMPI architecture with the 64-bit RS64 architecture in 1995. Applications compiled on systems using the IMPI instruction set could run on top of the newer RS64 systems without any code changes, recompilation or emulation, while also allowing those applications to avail of 64-bit addressing. There are two different formats of TIMI instructions, known as the Original Machine Interface (OMI) and New Machine Interface (NMI) formats. OMI instructions are essentially the same as the System/38 Machine interface instructions, whereas NMI