The What and Why of System z Millicode

Millicode as an advancement over microcode is arguably one of the best recent ideas in mainframe computer design. While microcode requires a distinct microcode processor to be designed and built, millicode shares the same processor that runs regular software, allowing it to take advantage of all the technology investment in that processor. In IBM mainframe processors, millicode is used to implement complex instructions, to implement other elements of the architecture and to provide system initialization, error recovery and other control functions. This presentation takes a look at z/Architecture millicode from a number of perspectives.

Tracks: z/OS Systems Programming and z/VM Systems Programming