Domain/OS - The early distributed Operating Systems
Post by: bond
Back in 1980's Domain/OS(Unix family) was developed by Apollo Computer Inc for Apollo/domain line of work stations. These Apollo/domain machines were built around the Motorola 68k family of processors, except for the DN10000, which had from one to four of Apollo's RISC processors, named PRISM(Parallel reduced instruction set machine). During that period Apollo's prism was for some time the fastest microprocessor available. PRISM was based on VLIW(very long instruction word) design. Whereas conventional processors mostly only allow programs that specify instructions to be executed one after another, a VLIW processor allows programs that can explicitly specify instructions to be executed at the same time (i.e. in parallel). This type of processor architecture is intended to allow higher performance without the inherent complexity of some other approaches.
Hewlett Packard purchased Apollo in 1989 supported the Operating system for a short period of time, later ending development of PRISM, although some of PRISM's ideas were later used in HP's own HP-PA Reduced instruction set computer (RISC) and Itanium processors.
This OS was considered the early distributed operating system. A distributed OS provides the essential services and functionality required of an OS, adding attributes and particular functional units(cpu operation and calculation) to allow it to support additional requirements such as increased scale and availability. To a user, a distributed OS works in a manner similar to a single-node, monolithic operating system(Entire OS working in kernel space and is alone in supervisor mode). That is, although it consists of multiple nodes, it appears to users and applications as a single-node.
