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APPENDIX A GLOSSARY The following list of terms is meant to add to the glossary provided in Part 1 of this Introduction. Most of the terms appear for the first time here, though several are repeated with expanded definitions.
One group of characters unbroken by blanks; it signifies one word to Multics. The characters may include alphabetic, numeric and some other characters (periods, hyphens, and underscores).
The state the computer is in when it is ready to accept command lines. You are at command level when you log in, when a command completes execution or encounters an error, or when you stop command execution by issuing a quit signal. Command levels above level 1 are indicated by the ready message.
The program that interprets command lines and calls the appropriate programs, after processing parentheses and active functions.
A part of an entryname. Entryname components are separated by a period (e.g., data_base is the second component of the entryname random.data_base.plans).
an unplanned termination of service from the front-end network processor causing a disconnection of the process. The process can be saved and reconnected when the -save_on_disconnect control argument has been used with the login command.
An unplanned termination of system availability caused by problems in hardware and/or software, often signalled by the message: MULTICS NOT IN OPERATION. Processes cannot be reconnected after a system crash.
A software system that integrates various computerized information units of an organization into a total system. With such a system, all users of data within an organization share common records of information and the information available at every level is drawn from the same source, providing mutually consistent levels of accuracy to all users.
The value or action that the system assumes when none has been specified by the user.
A name given to an item (segment or directory) contained in a directory. It may contain one or more components, separated by periods. All names given to entries within one directory are unique but need not be different from names used in other directories.
A path in the I/O system through which information is sent. For example, the normal output switch (user_output) is usually attached to the terminal, but it may be attached to a segment in storage by using the file_output command. This would save the output in a segment rather than print it at the terminal.
A communications control device which permits sharing of facilities by connecting the central processing unit to a large number of communications channels that may all transfer data to or from the processor at one time.
A unit of storage in Multics. A page contains up to 4096 characters.
A name of a segment or directory that specifies its location in the storage system. A pathname is either absolute or relative.
A segment name preceded by the series of directory names that lead from the root to that segment: each level in the pathname is preceded by a ">". For example, the absolute pathname for a segment under a user's home directory is designated this way:
All absolute pathnames begin with ">".
The pathname that uniquely locates a segment relative to the working directory, by listing the pathnames of directories under which the segment resides. For example, the relative pathname for a segment that resides in a directory one level under the working directory is designated this way:
All relative pathnames begin WITHOUT ">".
The activities (programs, data entry, etc.) of an individual user that begin when the user logs in, including absentee log in, and continue until logout or until another process is explicitly begun through use of the new_proc command.
The maximum number of pages that can be used in a hierarchy of directories. Each user is allotted a predetermined amount of quota; however, quota can be increased by a system administrator.
The structure of access control on Multics which is implemented by special hardware. Operation is controlled in such a way that the computer's work is done in a number of mutually exclusive subsets. These subsets may be considered concentric rings of privilege, representing different levels of access rights. The innermost or hardcore ring is made up of those segments essential to all users. This innermost ring, designated as ring 0, represents the highest level of privilege. The work of most users is done in ring 4. Ring 7 is the ring of least privilege.
The rules that specify the order in which directories are searched to find a command, subroutine, or data item. This is to be distinguished from addressing a segment by its pathname, which explicitly specifies the directory containing the segment.
A collection of programs that provide a special environment for some particular purpose, such as editing, calculation, or data management. It may perform its own command processing, file handling, and accounting.
The last component of an entryname, which often specifies the purpose of a segment (e.g., action.ec where ec specifies an exec_com segment).
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