Hardware-software interactions in SYMBOL-2R's operating system

Abstract

This paper describes the chief attributes of the Virtual Processor placed at the disposal of each user of the SYMBOL-2R time-shared multiprocessor system, and the mechanisms by which SYMBOL's hardwired operating system manages processing-mode transitions for individual Virtual Processors and allocates hardware resources -- processors and memory space -- among competing Virtual Processors. It describes the provisions by which the unusually high-level capabilities of the hardware are augmented by software, and contrasts the structure of the software component of the operating system with that of the hardware component. Finally, it describes the hardware/software partition of resource-allocation functions, in which allocation policies are controlled by software and executed by hardware.

Controlled information sharing in the SYMBOL-2R computer system

“…The functionality of the system described above is provided by SYMBOL'S hcirdware alone, with no software involvement other than for system initialization. The system's user services can be augmented, however, by system software, as described in [25] is primarily a convenience in referring to the set of services received by a given terminal, in SYMBOL (unlike most systems in which the concept is used) a virtual processor has a certain degree of tangibility, in the form of dedicated memory space (its "context block," which is defined below) and a dedicated terminal. The SYMB0L-2R system allows for 32 virtual processors (only three of which are equipped with physical terminals as this is written).…”