Abstract: An object-oriented software architecture interacts with "real" input/output devices exclusively through "virtual" input/output devices. Since all human interface with the operating system is performed through such virtual devices, the system can accept any form of real input or output devices. The lowest level of the operating system converts input from any physical device to virtual form and converts virtual output into suitable physical output. Any number of physical devices can be connected to, removed from, or replaced in the system without disrupting the system.

Abstract: In a computer human interface an abstract, device-independent "picture" is capable of containing multi-application information. A picture comprises a number of abstract picture elements which can be arbitrarily combined. A particular application attributes meaning to a particular organization of picture elements. No one application need be aware of the existence of any other, nor is it affected by any other, even though several applications may be sharing the same picture. A single, cohesive visual image, incorporating information from various applications, is presented on a suitable output device, such as a video display unit. Images representing portions of any or all of the applications can be displayed and updated on the output device simultaneously and independently of one another. User interface interface information, such as menus, icons, prompts, and help text, is also contained in the picture and may be displayed simultaneously with the application image(s).

Abstract: In a computer human interface an adjustable "window" enables the user to view a portion of an abstract, device-independent "picture" description of information. More than one window can be opened at a time. Each window can be sized independently of another, regardless of the applications running on them. The human interface creates a separate "object" (represented by a process) for each active picture and for each active window. The pictures are completely independent of each other. That is, none is aware of the existence of any other, and any picture can be updated without reference to, and without affect upon, any other. The same is true of windows. Thus the visual entity seen on a user's screen is represented by two objects: a window (distinguished by its frame title, icons, etc.) and a picture which is (partially) visible within the boundaries of the window's frame.

Abstract: A multi-processor, multi-tasking virtual machine comprises processes, messages, and contexts. Processes communicate only through messages. Processes may be grouped into contexts of related processes. Communication may be made between processes in different or related contexts or at the same context level.According to one message transmission mode, a message may be sent to each process with a given name within one context, thus ensuring that all processes with the same name at the same context level can be communicated with individually without knowing how many there are or where they are located.

Abstract: A data management system used by a digital computer system comprises a plurality of individual file systems which are connected together in a logical ring configuration around which file requests travel. File requests may be transmitted by the user to the "next" file system in the ring relative to the user.File requests optionally may or may not specify a file system name. If a file system name is specified, then the request is forwarded unidirectionally around the logical ring until either that file system name is found or the request returns to its starting point. If no file system name is specified, then an attempt is made to satisfy the request on each file system in turn until either the request is satisfied or the request returns to its starting point.

Abstract: A multi-processor, multi-tasking virtual machine comprises processes, messages, and contexts. Processes communicate only through messages. Contexts are groups of related processes. The virtual machine is implemented in a distributed data processing system comprising a plurality of individual cells coupled by a local area network (LAN). Each cell may comprise one or more processes and/or contexts.A network interface module (NIM) provides the interface between any individual cell and the LAN. To facilitate message transmission between processes resident on different cells, each NIM provides addressing modes allowing messages to be sent to processes according to the processes' names. Cells may be added to or deleted from the LAN, and processes may be created or deleted, without disrupting the LAN operations.