Multics 826 entries
16 Feb 2014

Glossary - N

Glossary of Multics acronyms and terms. Entries by Tom Van Vleck ([THVV]) unless noted.


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name
See additional names.

Nancy
Multics site: Centre Informatique Regional Interuniversitaire de Lorraine, Universite de Nancy 1 (Vandoeuvre Les Nancy, France)

NCP
[BSG] Network Control Program. (1) the set of ARPANet inter-host protocols that preceded TCP/IP (which latter made the Internet possible).

(2) The set of ring 0 Multics programs that supported this protocol in the Multics ARPANet implementation, written by Doug Wells and Ed Meyer, and discarded when TCP/IP took over. This system relied on the Host-to-IMP (Interface Message Processor) protocol, that supported in wired code by Raj Kanodia, which pioneered an event count technique for which he later acquired some fame. The Multics NCP involved a daemon which periodically called in to unload buffers of unfetched data from from ring 0. The NCP code was conceptually, stylistically, and implementationally isolated from the rest of ring zero, and was a bete noir to all Multicians except the aforementioned "network people".

NCSC
National Computer Security Center. This US government organization produced the Orange Book under the guidance of its Deputy Director, Dr. Roger Schell.

The NCSC operated the DOCKMASTER site.

NEC
Nippon Electric Company. Had a GE-645 in Tokyo in the early 70s.

new_proc
Terminate the user session's process and create a new one. This command reveals a deep weakness in the Multics design. A Multics process is expensive to create, so it runs commands and user programs inside the same process that contains the user's listener and shell. If these programs damage the process's machinery, such as its stack or combined linkage segment, the process may malfunction. The new_proc command destroys the current process and creates a new one, by sending an IPC message to the answering service. Until Multics was changed (about 1970) to refresh the linkage information for a program when it was recompiled, users used to have to new_proc every time they recompiled. Info segment for new_proc command

nothing
This command does nothing, as its name suggests. It's like the IEFBR14 routine of OS/360. It was written as the simplest test case for new command processor designs, and is still used in some exec_coms.

notify
[BSG] "Wait/notify" is one of two interprocess synchronization mechanisms used in Multics. "block and wakeup" is intended only for user programs. The overhead of event queues and the inability to wait on multiple events at once made it unsuitable for use in complex asynchronous subsystems (e.g., page control) in the supervisor. A process goes to "wait on" a given "event", a 36-bit number then recorded in the traffic control entry for the process. The process is suspended until some other process "notifies" that event, whereupon -all- processes waiting on it are resumed. Part of the protocol is the possibility of false notifications, the waiter must test upon resumption, and no datum is conveyed with the notification. Directory and other non-wired locks, as well as paging events, are managed with this mechanism.

notify timeout
In some cases a process might wait forever for a notify, due to a software bug or hardware problem. The scheduler will detect a process that has been waiting an unreasonable time and send it a notify, printing a message on the online console. Since the waiter always tests to see if the event "really" happened on resumption, this is safe. If a system started producing notify timeout messages, this was often a precursor of an impending crash.

NPS
Standard GCOS DN355 software. Multics could run with this as well as its own, more functional, MCS.

NPT
New Product Test. GE and Honeywell organization that tested each new CPU in Phoenix after it was built, in an area of the DVCP manufacturing floor called the "test cell." In the late 70s, lack of test cell capacity was a limiting factor on LISD's ability to deliver Multics CPUs.

NSA
(1) US National Security Agency. Multics customer. See Site N and DOCKMASTER. There were two DOCKMASTER systems; the last one shut down on 3/31/98. Bob Morris was Principal Scientist at NSA after he left BTL. The National Computer Security Center was part of NSA; Roger Schell was Deputy Director of the NCSC when it produced the Orange Book. See the DOCKMASTER site history.

(2) New System Architecture. A domain-based architecture extension to the 6000 architecture invented by John Couleur. This complex addition to the GCOS machine was incompatible with the Multics changes. Honeywell forced all of its GCOS customers to switch to CPUs that supported this architecture, but the GCOS supervisor never used much of it. This battle was one of the reasons for the Palyn Report.

NSS
New Storage System. MR 4.0 included a rewritten storage system that supported more disk devices and improved fault tolerance and recovery. Story: "The New Storage System". Story: "It Can Be Done".

NSW
[DMW] The National Software Works (NSW) was an Air Force research project to build a geographically distributed, fault-tolerant computing system on top of existing operating systems. The primary players were Mass. Computer Associates, BBN, MIT, SRI, and UCLA. The underlying protocol provided access to resources, much as FTP and RSEXEC did. The difference was that the resources were abstract and at a higher level than the individual host environments. When a process wrote a file, the file was created and stored locally. The file was stored in a structured format (like OS/MVS, MacOS, VOS, etc), such that it could be translated for other systems. Thus, the output of a text editor could be read by various programs (on various host types) and the lines/records would be automatically translated into records or lines, as appropriate, and lines would have the expected termination chars. A background task would copy the files onto other systems to provide redundant versions in the case of a host shutdown or failure.

Commands were also virtual/abstract, and when someone asked for TECO, he/she might be provided a TECO running on an arbitrary TENEX host someplace. In fact, if someone asked to run an editor, he/she might be provided a TECO running on a TENEX, an edm (or was it qedx) running on Multics, or something running on an OS/MVS system.

The Multics NSW server included a File Server and an environment to run commands. Because the execution environment included the capability for compilation, however, the NSW Server actually executed commands by creating processes and running the programs in those processes.

NTT
[BSG] Nippon Telephone. Built a Multics-inspired system, the NTT DIPS. DIPS was an operating system developed by NTT and running on IBM S/370 clone machines built by Hitachi, Fujitsu and NEC. Sure, it was inspired by Multics, but was not a clone, or you would call every multi-user machine built after 1970 a Multics clone.

NWGS
US Naval War Games System. A set of 4 systems installed by CSC to support the US Naval War College, War Gaming Division, Newport, Rhode Island. See NWGS site history.