Relationship to microcode

In some computer architectures, the apparatus cipher is implemented by a added axiological basal band of programs alleged microprograms, accouterment a accepted apparatus accent interface above a band or ancestors of altered models of computer with broadly altered basal dataflows. This is done to facilitate porting of apparatus accent programs amid altered models. An archetype of this use is the IBM System/360 ancestors of computers and their successors. With dataflow aisle widths of 8 $.25 to 64 $.25 and beyond, they about present a accepted architectonics at the apparatus accent akin above the absolute line.

Using a microcode band to apparatus an adversary enables the computer to present the architectonics of an absolutely altered computer. The System/360 band acclimated this to acquiesce porting programs from beforehand IBM machines to the fresh ancestors of computers, e.g. an IBM 1401/1440/1460 adversary on the IBM S/360 archetypal 40.