Modern central processor architecture

A number of significant architectural concepts which have evolved in recent years are reviewed. These concepts are: the notion of process and the facilities for process management, such as dispatching and synchronization; the use of segmentation in organizing address spaces, and the resulting sharing and protection capabilities; the control of access to data and procedures via multiple privilege levels; the use of automatic stack management for procedure calling; and the structure of logical and physical I/O channels and I/O operations queueing. The rationale for including these concepts in modem central processor architectures, such as in the Honeywell Series 60, is also presented.