One significant exception to this is the AS/400, software for which is compiled into a virtual instruction set architecture (ISA) called "Technology Independent Machine Interface" (TIMI); TIMI code is then translated to native machine code by low-level software before being executed. The translation software is all that must be rewritten to move the full OS and all software to a new platform, as when IBM transitioned the native instruction set for AS/400 from the older 32/48-bit "IMPI" to the newer 64-bit "PowerPC-AS", codenamed "Amazon". The IMPI instruction set was quite different from even 32-bit PowerPC, so this transition was even bigger than moving a given instruction set from 32 to 64 bits.