Multics 843 entries
20 Apr 2024

Glossary - F

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

Index| A| B| C| D| E| F| G| H| I| J| K| L| M| N| O| P| Q| R| S| T| U| V| W| X| Y| Z|
Restaurant in Kendall Square, Cambridge, where Project MAC Multicians used to go to lunch. Run by the Fox and Tishman family. Not to be confused with the F&T Diner next door. Torn down during the late 1980s.

[BWS] Feature of MR11.0. File Access Methods and Integrity Services. it was an early name for the Data Management (DM) version of MRDS that supported transactions and before journalling. Beta tested at Ford in 83/84.

[VS] This is a file access method that supports atomic transactions (including commits and rollbacks). It was designed to provide MRDS with transaction capabilities.

DTSS simulator, with command conventions made more like Multics. DFAST was a more strict simulation of the Dartmouth system. Both used the same BASIC compiler.

fatal error
A Multics process can terminate for a number of reasons, such as running off the end of its stack, taking a fault in the fault handling mechanisms, or getting an error writing an error message. In such cases, the answering service prints a message like

Fatal error. Process has terminated. Fault in signaller. New process created.

and simulates a new_proc command for the user.

[BSG] Processor generated exception causing a diversion of control through a fault vector, for any reason except an interrupt. Page faults, segfaults, bad instructions or out-of-bounds references and the like are all common faults. (There is no notion of "failure").

BOS did not take or process any type of faults. When Noel Morris made BOS tapes self-booting (see Zero Six Dog), though, the coup d'étape, as it were, was the processor taking a horrible "trouble fault" by executing one of the magic constants on a "Multics Standard Tape" (see MST) and Noel's code handling it, not unlike the swift whap on the buttocks of a new-born babe. But field engineers not savvy to Multics culture were unimpressed that "Multics starts up by taking a fault." (setting the "stop on fault" CPU switches up was part of their S.O.P.)

fault vector
[BSG] Set of 32 instruction pairs in a fixed location specifying CPU handling of the 32 processor faults. Rather than specifying a location to transfer to, the 600/6000 architecture specified a pair of instructions to be executed out of line in absolute mode by the control unit, one of whose tasks was "executing pairs of instructions, no matter how obtained." The first instruction was invariably SCU, and the second, "return", because the Multics return instruction also reloaded the condition code register, which in the case of interrupt vectors was ingeniously used to stash the interrupt number!

BOS command that takes a core dump into a disk partition instead of printing it on the printer. The saved dump can then be analyzed by ifd.

Field Engineers
FEs were Honeywell employees who installed the big iron and fixed it when it broke. They were an incredibly dedicated group of people, who worked long and strange hours, and responded without complaint to panic calls when the machine wouldn't work. They dealt cheerfully with an exotic, undocumented CPU built far away, running software that changed all the time, and kibitzing by a lot of people who provided unhelpful theories and lots of pressure, but not enough recognition.

See segment.

File manager
See vfile_.

file map
Data structure that lists disk record addresses for each page of a segment. Stored in the segment's VTOCE.

file system
Multics was the first operating system to introduce a true hierarchical storage system, in which a directory could contain other directories.

The paper "A General-Purpose File System For Secondary Storage" describes the 1965 design of the file system.

Fault Interceptor Module. This program is invoked whenever the hardware encounters a fault. It manages machine state and calls the appropriate routine. Harlow Frick, Noel Morris, and Tom Van Vleck worked on the original version. In later years, there were actually two FIMs, wired_fim and fim, for faults whose handling has to be done in page-locked environment and not. Source code: fim.alm.

[BSG] PL/I condition signalled in a process at logout time (by the logout command) to allow handlers set up earlier to close open PL/I files and the like. This was a fairly late addition, because Multics' file model, a virtual memory view of disk via shared segments, is not PL/I's, and there is little need for such handlers. But they can still cause trouble -- see jladdae.


Firehose drum
See Librafile.

Fall Joint Computer Conference. There used to be two big AFIPS conferences a year, one in the spring and one in the fall. Multics was first announced at the 1965 FJCC. See "Introduction and Overview of the Multics System".

Function Language. An assembler that Tom Kinhan of GE CISL was working on but that was never made part of the system.

Flag Day
Any software change that is neither forward nor backward compatible. Named after a change to Multics scheduled for June 14, 1966, when the values of the ASCII character set were switched around.

Typewriter device made by Friden, which could punch paper tape or type the contents of a paper tape. Flexowriters were used on the very first demonstration versions of CTSS, and were used to prepare MSPM documentation.

Honeywell machine, planned as a Multics platform in the 1980s. Planned to be a 3-4x faster machine using gate array technology provided by Honeywell's DoD-funded Very High Speed Integrated Circuit (VHSIC) program. This machine was simulated but never built, and the project was canceled in March 1985. Story: "Flower"

Command that causes lots of paging by creating many large segments and touching the pages. It is used for performance benchmarks and system debugging.

[MTB-607] Front-end Network Processor. Also called FEP. See SFEP.

Multics supported two models of the FNP. The Datanet 355 (later known as the Datanet 6632) provided the original communications support for 6180 Multics. (645 Multics used the GIOC for communications I/O.) The Datanet 6661 (and its predecessor, the Datanet 6678) were reimplementations of the 355 architecture using Level 6 minicomputer technology.

The FNP software supported the following protocols:
  • Asynchronous ASCII
  • IBM 1050
  • IBM 2741
  • ARDS
  • Honeywell G115
  • Terminet 1200/202 modem
  • Honeywell VIP
  • X.25 level 2
  • IBM 3270
  • HASP
Support was also provided for Automatic Calling Units (ACU's) and the COLTS on-line T&D's.

In 1983, the FNP code contained about 40,000 lines of 355MAP code.

[THVV] Article: Multics Communications and Networking.

Ford Motor Company. Big Multics customer. Ford had Multics twice. In 1974-1975 Multics was used at Ford on a trial basis. It came back in 1978 and was used until 1997. Site history and story: Ford.

[PWB] (Short name, fdoc.) Primitive Multics text formatting command. Written by Paul Benjamin of Honeywell FSO McLean. It was written during the EOP benchmark when it was determined that compose was too slow and runoff might soon be unsupported. Unbundled product.

format_document_ was the text formatting subroutine derived from fdoc. Written by Paul Benjamin of PMDC. Used by many Multics commands that had text formatting requirements, such as forum and the mail system. Info segment for format_document command

PL/I indenting program with many features, options, and control arguments. Stan Dunten wrote IND in MAD on CTSS, and Tom Van Vleck ported it to Multics as indent. This program had few options and understood only a subset of PL/I. Paul Green created the much more powerful and flexible format_pl1, and Monte Davidoff finished it up, fought all the MCR Board battles, and got it installed as a command. Info segment for format_pl1 command

In addition to being used for "prettifying" programs, format_pl1 became a tool for canonicalizing programs for textual comparison. For better or worse, it also became a tool for eliminating stylistic variation in PL/I code formatting.

Multics had three fortran compilers. Version 1 FORTRAN was written using POPS by Ke Shih at GE/CISL.

[PG] The version 2 compiler was written in PL/I at CISL, and shared a back end code generator with the PL/I compiler.

[RAB] The last Multics Fortran compiler was written at CISL by David Levin, Paul Smee, and Richard Barnes. M. Donald MacLaren did a lot of design work for that compiler, designing the non-optimizing IL (Polish) and code generator. I wrote both optimizing and non-optimizing code generators and the optimizer, designing the optimizing IL (quads). David Levin wrote the parser. Paul Smee wrote a converter from non-optimizing IL to optimizing IL that did some semantic processing as well.

(1) Bulletin board system. A descendant of Pat Doherty's continuum from USGS, rewritten by Mike Auerbach, J. Spencer Love, Jeff Schiller, and Jay Pattin at MIT as ring 3 site code. Renamed from continuum at French insistence because the short name, "con," was obscene slang in French. Unbundled product released in MR 10.0. Paper: "Experiences with an Interactive Electronic Meeting Facility". See also xforum

(2) name of the HLSUA user meetings, e.g. Forum XXVI.

As in core frame, or page frame. A 1024-word block of main memory that can either hold a page or be free. The table of core-frames (the CMP, core map, entries CME, or core-map entry) are in the SST.

ARPANet interface board. See ABSI.

File System Device Configuration Table. Held file system parameters and volume maps (until the new storage system).

File System Interface Module.

Federal Systems Operation. The division of Honeywell that handled government contracts, sales, etc. Succeeded by HFSI, Inc.

[Allen Grider] Getronics Government Solutions, LLC. was sold by Getronics and became DigitalNet Government Solutions LLC in December 2002. (owned by DigitalNet). This company can trace its roots back to the Federal Systems Division of Honeywell. So the progression is now:
  • Federal Systems Division of Honeywell
  • Honeywell Federal Systems, Inc. (when Honeywell sold the computer division to Bull, but not us)
  • HFS, Inc. (when Honeywell finally sold us to Bull)
  • Wang
  • Getronics Government Solutions, LLC (owned by Getronics)
  • DigitalNet Government Solutions, LLC (owned by DigitalNet)

[Ed Langmaid] BAE Systems purchased DigitalNet Government Solutions in November 2004.

Fault Tag 2, a hardware indirection indicator that causes a specific fault, used in Multics to cause a linkage fault.

File Transfer Protocol. Moves files between machines on the ARPANet.