UOS Glossary and Article Index

Absolute date/time: A specific date and/or time value. As opposed to relative, delta, or combination date/times. Described in article 78
Access Control List: A list of specifications that modify file protections, allowing or denying access to specific users. First discussed in article 39
Access Mode: The way in which a device is accessed: sequential or random-access. First discussed in article 48
Access Type: The manner of accessing a user account; typically batch, interactive, network, or remote. First discussed in article 42
ACE: Access Control Entry. An entry within an Access Control List.
ACL: See Access Control List
Allocation Chain: A single-linked list of allocation clusters.
Allocation Cluster: A cluster containing pointers to allocated data clusters.
Allocation Table: A bit array indicating which clusters of a store are in use. First discussed in article 10
Allocation Type: Types of memory, such as data, instruction, and stack. First discussed in article 31
ANSI: American National Standards Institute. When used as a stand-along term, it means a character encoding standard - a superset of ASCII. First discussed in article 50
ASCII: American Standard Code for Information Interchange. A character encoding standard. First discussed in article 50
ASTLM: Asynchronus I/O limit. A quota restricting the number of simultaneous asynchronous I/O requests. First discussed in article 42
AST: See Asynchronous System Trap
Asynchronous I/O: An I/O operation that does not block the process.
Asynchronous System Trap: VMS terminology for asynchronous callbacks from the executive to applications. First discussed in Article 64
Authentication: The process of ensuring that someone has legitimate access to an account. First discussed in article 42
Bad Block file: A file consisting of flawed clusters on the store. First discussed in article 13
Command Line Interface: A non-graphical shell, such as UCL.
CPUTIM: A quota used to limit the number of CPU seconds that a process can use. Discussed in article 195
CR: Carriage Return. A control character used to move to the start of a line. First discussed in article 50
BEL: A control character that typically sounds a tone when output. First discussed in article 42
BIOLM: Buffered I/O limit. A quota restricting the number of buffered I/O operations per session. Discussed in article 42 and article 58
BIOS: Basic I/O System. In general, any hardware and/or software system that provides a basic interface to hardware devices. In a PC, it is firmware that is essentially a set of drivers for the hardware supported by the motherboard.
Blocked: A process state indicating that it is waiting for some event to complete. Discussed in article 195
Boot Block: The first sector of a disk, reserved for the bootstrap. First discussed in article 10
Bootstrap: The program which starts up the operating system. First discussed in article 10
Buffered I/O: An I/O operation that uses an intermediate system buffer. First discussed in article 42
BYTLM: Bytelimit. A quota restricting the number of bytes in I/O operations per session. Discussed in article 42 and article 58
Channel: Synonym for Handle.
Character Folding: A process used to convert Unicode characters to lowercase. See Unicode.
CLI: See Command Line Interface.
Cluster: A collection of contiguous data which is a multiple (1 or more) of the basic allocation unit of a store. On a hard disk, the smallest cluster is a single sector. First discussed in article 4
Combination date/time: A date/time specification consisting of both an absolute and delta date/time. Described in article 78
Command Abbreviation: A way for defining commands that can be abbreviated in UCL. Discussed in article 63
Command File: A file containing a UCL script. First described in Article 45.
Command Line interface: The textual interface to an operating system, also known as a shell. Described in Article 45.
Command recall: A service which retains previously entered input lines and/or commands that can be reused. First discussed in article 140
Commonly Used System Programs (CUSPs): Programs provided as part of UOS. Unlike the Executive, these programs make up the user-interface to UOS and add functionality to what the Executive offers. Programs used by most/all UOS users, as opposed to utilities.First discussed in article 27
Computable: A process state indicating that it is ready to be scheduled for execution. Discussed in article 195
Console: The terminal used for system startup. First discussed in article 19
Control character: Non-glyph character value which performs special operations on devices. First discussed in article 50
Cooked data: Data which has been processed - as opposed to raw data. First discussed in article 50
CPUTIM: CPU time limit. A quota restricting the total number of CPU seconds that can be used per session. First discussed in article 42
CR: Carriage Return. A control character used to move to the start of a line. First discussed in article 50
CUSP: See Commonly Used System Program.
Data sanitation: The operation of removing all traces of data from a disk, short of physical destruction. Used for disks with highly-classified data. Discussed in article 21
Data Stream: An independent collection of data. For instance, a file's content is stored in a data stream. First discussed in article 8 and expanded on in article 144
Date/Time Codes: Codes which indicate specific parts of dates or time and the formatting thereof. First described in article 78
Date/Time specification: Specification for date, time, or both. UOS date/time specifications can be abosolute, delta, or combination. First described in article 78
Delta date/time: A relative date is an offset day/hour/minute/second from the current or absolute date. As opposed to relative, absolute, or combination date/times. Described in article 78
Device Class: The class of device: store, stream, or other. First discussed in article 48
DIOLM: Direct I/O limit. A quota restricting the number of direct I/O requests. First discussed in article 42
Direct I/Os: Direct I/Os, as opposed to buffered I/Os. These are I/O's whose buffers are in user memory. First discussed in article 42
Directory: Synonym of Folder.
Dismount: The opposite of Mount. In the case of a disk, this involves flushing all data, such a the allocation table, to the store.
Display Management services: UOS system services that manage output to displays and/or terminals. First discussed in article 189
DMG: See Display Management services.
Dynamic disks: Disks not associated with a specific disk controller, partition, or RAID set. First discussed in article 25
Echo: The process of outputting a character in response to a character being typed on a terminal. Also called full-duplex, as opposed to half-duplex where no character is output. First discussed in article 20
Effective privileges: The set of privileges that a process has at the moment.
Emancipated object: A reference-counted object that deletes itself when no longer referenced. Discussed in article 6
ENQLM: Lock queue limit. A quota restricting the number of simultaneous locks. First discussed in article 42
EOF: End of File. This is the logical file size, which is equal to, or smaller than, the size allocated on the store for the file. This is essentially a "high-water" mark that indicates the last byte written to the file.
ESC: Escape. A control character. First discussed in article 50
ETIME: Elapsed Time limit. A quota restricting the amount of elapsed (connect) time per session. First discussed in article 42
Event Flags: Flags used to synchronize asynchronous operations. First discussed in article 193
Exception: An unexpected condition or error. Discussed in article 6
Executive: The core of the UOS operating system. First discussed in articles 19 and 27
Extendable store: A store whose size can be dynamically changed while in use. Discussed in article 40
Expression trees: A data structure used to store an expression for later evaluation. Discussed in article 66
Extent: A fragment of a file. First discussed in article 3
FF: Formfeed. A control character used to move to the top of the next page. First discussed in article 50
File Handle: A Handle for a file.
File Header: The data structure used to store meta data about a file. Discussed in article 8
File Heap: A heap implemented in a file store. Discussed in article 40
File Processor: The executive component responsible for device, file system, and file management and I/O. First discussed in article 36
File Protections: The combination of flags indicating which users can perform which operations on files. First discussed in article 39 and further discussed in article 177.
File Store: A store implemented in a file. Discussed in article 40
File System: A data structure on a store used to manage files. First discussed in article 3
File System file: A file containing a file system. Discussed in article 184
File System services: System services used to manage File System files.
FILLM: File Limit. A quota restricting the number of simultaneous opened files. First discussed in article 42
FiP: See: File Processor.
Folder: A collection of files and other folders. First discussed in article 10
Footprint: The amount of space required on disk and/or in memory.
Forced login: A login requested by the executive that occurs without authentication or other considerations. First discussed in article 10
FS services: See File System services.
Full duplex: See echo.
GETDVI: A system service that returns device information. First discussed in article 62
GETJPI: A systen servuce that returns job/process information. First discussed in article 68
Granted privileges: Privileges granted to a user.
GUID: Globally Unique IDentifier. A 128-bit value used to unqiuely identify things. Discussed in article 24
GUID Partitions: A partitioning scheme used to replace MBRs. Discussed in article 23
HAL: Hardware Abstraction Layer. The component that interfaces UOS to the hardware platform that it is running on. First discussed in article 19
Half duplex: See echo and Local Echo.
Handle: A value used to uniquely identify a resource for access from the process. First discussed in article 52
Hashlib: A set of hash and encryption/decryption routines provided with UOS.
Heap: A type of managed store.
Heap Fragmentation: A situation in which the free memory exists in several small chunks. This can result in there being enough free memory, but not enough contiguous memory to fulfill a request. First discussed in article 28
Heap Management Component: A class which allocates, deallocates, and reallocates memory in a Heap. First discussed in article 28. Discussed at length in Article 32
Help: 1. Text documenting use of CUSPs and utilities. 2. Libraries containing such text. 3. A CUSP used to access help text. First discussed in article 179
HMC: See Heap Management Component.
Hooking: The process of making UOS bootable by including pointers to essential files in the boot block and file system header. Discussed in article 30
HT: Horizontal Tab. A control character used to move to the next tab stop. First discussed in article 42
I18N: An abbreviation for "Internationalization".
Image Rundown: The process of ending a running image, including releasing resources the image used. Discussed in article 145
Init: The secondary bootstrap for UOS. Used to load UOS and to provide the user with configuration options prior to booting UOS. Discussed starting in article 19
Internationalization: The state of being able to be customized to a specific nation, language, and/or locale. First described in article 78
Interprocess Communication: Direct communications between different processes. First discussed in article 196
IO_SETMODE: A means of setting up ASTs for terminal interrupts.
I/O Devices: Any device used for reading/writing (input/output). A device consists of three tiers: tightly-coupled hardware, loosely-coupled hardware, and media. Discussed starting in article 48
I/O Filters: Classes used by terminals to cook input and output data. First discussed in article 50
Executive startup: The first phase of UOS startup, where the Executive is loaded and set up. First discussed in article 27
Kernel: In most operating systems, this refers to the core of the O/S. In UOS, the Kernel is part of, and responsible for, loading the components of the Executive. It coordinates activity between them, and provides an interface for them to the rest of the system. Described in articles 19 and article 27
Labels: Targets for code flow in UCL command files. Discusssed in article 59
LBR services: System services that allow management of library files. First discussed in article 180
Layered architecture: An architecture where software components are built in a hierarchy resembling, in diagrams, layers in a cake. Also known as a Stack architecture. Discusssed in article 27
Lexical Functions: Scripting functions used in UCL. Named for the fact that they are executed during the lexical processing of the command line. First discussed in article 74
LF: Linefeed. A control character used to move to the next line. First discussed in article 50
LGICMD: Login Command file. The command file run when a user logs in. First discussed in article 42
Library: A collection of files in a directory or a library file.
Library file: A file system file containing collections of files, called modules. Discussed in article 179
Librarian: A utility used to manage a library file. Discussed in article 182
Links: See Symbolic Link.
Local echo: When a terminal displays a character as it is typed. See also Echo.
Localization: See Internationalization.
Locked pages: A page of memory that has been marked to stay resident in memory. First discussed in article 47
Logging in: The process of presenting authentication to be allowed access to the computer. The process is done via the LOGIN utility.
Logging out: The process of ending a session that was started by logging in. First discussed in article 146
Logical device: A redirection via symbols which is used like a device name. First discussed in article 35
LOGIN: The program that logs a user into the system. First discussed in article 150
Mailbox: A virtual stream used for interprocess communication and/or synchronization. First discussed in article 196
Managed Store: A store that keep tracks of what areas of the store have been used, and allows us to allocate/deallocate areas of the store. Heaps are an example of managed stores. Discussed in article 4
Mapped pages: A page of a process' virtual memory that has been made available in the virtual memory of another process, or the executive. First dsicussed in article 47
MAXACCTJOBS: Maximum Account Jobs. A quota restricting the number of non-network processes that can be simultaneously active. First discussed in article 42
MAXJOBS: Maximum Jobs. A quota restricting the total number of processes that can be active simultaneously. First discussed in article 42
MBR: Master Boot Record. A structure stored in the boot block that defines how the disk is partitioned. Discussed in article 23
Memory Management Component: A component that interfaces with the HAL and provides memory management for UOS. Discussed in article 31
Meta data: Data that is about data. For instance, a file's name isn't data, it is the name associated with the actual data. Discussed in article 8
MFA: Multi-Factor Authentication.
Mirror manager: A class that manages multiple mirror sets. Discussed in article 24
Mirror set: A collection of stores being used in mirroring.
Mirroring: A form of RAID which replicates exact copies of a store for performance and data reliabiligy. First discussed in article 24
MMC: Memory Management Component.
Mount: To make a device ready for use. In the case of a disk, this involves loading the store header and allocation table, and validating the file structure. Discussed in article 37
Multi-Factor Authentication: Authentication that involves more than one form of authentication. Used for increased security.
NUL: Null. A control character that typically does nothing. First discussed in article 42
Null Device: A device name not associated with a physical or virtual device. Discussed in article 36
OPCOM: A detached process that logs and manages system messages. First discussed in article 196
Operator: A user who performs manual tasks such as changing printer paper and loading/unloading removable media. First discussed in article 196
Owner: The user who created a file or has been designated as the owner of a resource.
Page: The unit of minimum allocatable memory. First discussed in article 31
Page List: A list of pages allocated to a process or to the executive. First discussed in article 31
Page Table: A table of all possible pages in physical RAM. First discussed in article 31
Password: A secret sequence of letters/symbols used to authenticate access to a user account.
Partition: A contiguous area of a store that is treated as an independent store. Discussed in article 23
Patterns: A series of bit patterns used to test a store for bad sectors. First discussed in article 13
Preempting: Suspending the execution of a process in order to run another one. Discussed in article 195
PGFLQUOTA: Page File Quota. A quota restricting the number of page file pages that can be used by the user. First discussed in article 42
PRCLM: Process limit. A quota restricting the number of simultaneous processes that a user can have running. First discussed in article 42
Priority: An integer value from 0 to 255 indicating relative priority of processes. A higher number indicates a greater priority. Discussed in article 195
Private Stores: Stores that do not take part in the Public Pool.
Privileges: Flags associated with users and programs that allow special abilities. First discussed in article 39
Process Scheduling: See Scheduling.
PROCESS_SCAN: A system call used to iterate through current processes. First discussed in article 70
Program privileges: Privileges granted to a prcess while a privileged program is running.
Prompt: A sensory indication that software is ready for user interaction.
Protections: See File Protections.
Psuedo-random Numbers: Numbers which are generated by an algorithm but which appear random. Discussed in article 24
Public Pool: A collection of stores that are treated as one large logical file system and are available for general use. Discussed in article 37
Public Storage Pool: See Public Pool.
Public Stores: Stores that take part in the Public Pool.
QIO: The I/O routine used by VMS and UOS. First discusssed in article 55
Quantum: The minimum amount of CPU time a process is allowed before it is preempted. Discussed in article 195
Quotas: Limits placed upon the use of some system resources to prevent one process from affecting others by using too many of those resources. First discussed in article 42
RAB: Record Access Block. A structure used by RMS. First discusssed in article 53
RAID: Redundant Array of Independent Disks - a stragegy of using multiple disks as a single logical volume for purposes of reliability and/or performance. First discussed in article 24
RAM Disk: An in-memory store. Discussed in article 25
Random Numbers: See psuedo-random numbers.
Raw data: Data which has not been processed - as opposed to cooked data. First discussed in article 50
Real-time: Processes which run in response to events, preempting other processes even if those processes have not reached their quanta. Discussed in article 195
Reallocation in-place: The process of resizing a chunk of allocation memory without changing its position. Discussed at in Article 32
Recall: See Command recall.
Redirection Constant: A reserved handle value used as an indirect reference to the handle associated with a redirection. Discussed at in Article 52
Reference Store: An up-to-date store which is used to update other stores that. Discussed in article 24
Relative date/time: A specification indicating yesterday, today, or tomorrow (relative to the current date/time). Described in article 78
Reserved Memory: Memory reserved for the executive. First discussed in article 31
RH_Command: Redirection constant for the handle associated with SYS$COMMAND.
RH_Error: Redirection constant for the handle associated with SYS$ERROR.
RH_Input: Redirection constant for the handle associated with SYS$INPUT.
RH_Output: Redirection constant for the handle associated with SYS$OUTPUT.
Ring: A CPU protection mechanism that operates as concentric circles of access to hardware features. Described in Article 45.
Ring Queue: A queue with a fixed buffer where data wraps from the end to the beginning of the buffer. Described in article 50
RMS: Record Management Services. An I/O software layer that cooks data for files. First discusssed in article 53
RNG: Random Number Generator. Something that generates psuedo-random numbers.
Rotational latency: The time it takes for a sector on a disk to rotate into position for read or write. Discussed in article 24
Scheduler: The code which determines which processes run. Called on each system timer interrupt. Discussed in article 195
Security Reference Model: An architecture/approach to security that involves three entities: the requestor, resource, and database. Discussed in article 39.
Seek time: The time it takes for a disk read/write head to move to a target track. Discussed in article 24
Shell: The user interface for an operating system. Some systems have multiple shells. In the case of Windows, for instance, there is the Windows GUI and command-line box.
Quantum: The minimum amount of CPU time a process is allowed before it is preempted. Discussed in article 195
Simulator: Software or hardware that is functionally identical to other hardware.
SNIA: A standard for RAID support structures. Discussed in article 24
Spanned Sets: A set of stores that are treated as a single larger store by logical concatenation of their clusters. Discussed in article 37
Spawn: The creation of a process by another process. Discussed in article 168
SSC: See System Services Component.
Starlet: The library that provides direct access to the UOS executive and a developer-friendly API for UOS. First mentioned in Article 45.
Startup: See System Startup and Startup account.
Startup account: A special hard-coded user account (UIC=1) used for system startup and system setup. Discussed in article 43
Stream: See Data Stream.
Store: Anything that we can store data on and read it back from. A common example of a store is a hard disk. But there are other stores as well, such as floppy disks, files, and memory. Stores have a generic interface in UOS, which allows us to deal with them in a general fashion. For example, a file system could exist on a store that is a disk partition, or in RAM (eg a RAM Disk), or even within a file that exists on another store (a container file). Stores can be fixed in size (such as a disk), or expandable (such as a file). Discussed in article 4
String table: A collection of string values, including a count of references to each one. Discussed in article 12
Sub-Heap: One of many smaller heaps that, together, make up one large heap. Discussed at length in Article 32
Symbol table: Collections of symbols. Symbol tables exist for each process, each job, the system, and the cluster. First dsicussed in article 35
Symbol substitution: The process of customization in UCL command files where symbol values are substituted for symbol names. Substitution occurs in two phases. Discussed in articles 59 and 60
Symbolic Link: A file which serves as an indirect reference to another file. Discussed in article 174
Symbols: Values accessed by name in collections called symbol tables. First dsicussed in article 35
SYS$COMMAND: A logical used to redirect command input.
SYS$ERROR: A logical used to redirect error output.
SYS$INPUT: A logical used to redirect input.
SYS$LANGUAGE: A symbol used to indicate the user's preferred language. First dsicussed in article 78
SYS$OUTPUT: A logical used to redirect output.
System Operator: See Operator.
SYSUAF: System User Authorization File. The file is a file heap that contains the definitions and attributes of users. Discussed in article 42
System account: A user account with a UIC less than 8. First discussed in article 43
System programs: See CUSPs.
System services: Utility routines provided with UOS that can be used by programmers.
System Services Component: A class which provides general services for the executive. Discussed in article 35
System startup: The second phase of the UOS startup. First discussed in article 27
System User: A user with a low UIC (usually 1-7).
Terminal: A logical serial I/O device used to communicate with a user. First discussed in article 19
THREADLM: Thread limit. A quota restricting the number of simultaneous threads per process. First discussed in article 42
Timesharing: The sharing of the CPU by multiple concurrent proceses. Discussed in article 195
Timestamps: UOS date/time values are stored as 64-bit integers that indicate a date and time. The values indicate the number of nanoseconds since 12:00:00 AM, January 1, year 0, projecting the Gregorian calander back. Discussed in articles 8 and 78
TOFF_: Terminal output Filter Flag. Flags used to control how to cook output data. First discussed in article 42
TQELM: Timed Queue Event Limit. A quota restricting the number of simultaneous active timers that a process can have active. First discussed in article 42
TResource: A class used to associate a process with a a file - the instance address is the handle.
TRNLNM: A systen servuce that returns symbol (logical) information. First discussed in article 68
Turn: The operation of moving from one allocation cluster to another, by following a pointer and reading the next cluster. Discussed in article 5
TUUI: A class used to manage user interfaces for CUSPs and utilities. Described in Article 154.
UCL: UOS Command Language. A scripting language for UOS and also the name of the shell that executes the script. First described in Article 45.
UCL Expressions: Syntax used to evaluate numeric, string, and logical operations. First described in Article 65.
UCL Tokens: The individual parsable items in a UCL command. Described in Article 61.
UHTML: A subset of HTML supported natively by UOS.
UIC: User Identification Code (see User).
Unicode: A standard for universal support of the glyphs for all languages. Described in Article 17.
Unisys: A state in which a process is given sole execution on the system. Discussed in article 195
UOS: Universal Operating System.
UOS simulator: A hardware simulator for UOS that runs on Windows.
UOS startup: The process of starting UOS, consisting of two phases: Executive startup, and System startup. First discussed in article 27
User: A numeric identifier (UIC) used to authenticate access to UOS, control access to resources, and track usage. UICs have unique names associated with them. First discussed in article 39
Utility: Programs provided as part of UOS, used primarily by system administrators and/or programmers. As opposed to CUSPs.
UUI: Universal User Interface. A standard for defining a user interface. First described in Article 154.
Virtual store: A store which is not associated with a dedicated hardware device. A RAM Disk is a type of virtual store.
Wildcard: A character used to represent other characters for matching purposes. Described in Article 17.
WSDEFAULT: Working Set Default limit. A quota indicating the number of pages of physical memory that a process is given by default. First discussed in article 42
WSMAX: Working Set Maximum limit. A system parameter defining the maximum number of pages of physical memory that a process can own. First discussed in article 145