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67-427: An addendum may explain inconsistencies or expand the existing work or otherwise explain or update the information found in the main work, especially if any such problems were detected too late to correct the main work. For example, the main work could have had already been printed and the cost of destroying the batch and reprinting it deemed too high. As such, addenda may come in many forms—a separate letter included with

134-412: A machine word . Further, when data corruption occurs in a text file, it is often easier to recover and continue processing the remaining contents. A disadvantage of text files is that they usually have a low entropy , meaning that the information occupies more storage than is strictly necessary. A simple text file may need no additional metadata (other than knowledge of its character set ) to assist

201-410: A commentary known as a rider , as in the prosecution of Harold Greenwood and the inquest of Jean Charles de Menezes . Addendum is also used if the medical care staff is inserting additional information about the patient. The addendum is the radial distance from the pitch circle of a cogwheel, worm wheel, etc., to the crests of the teeth or ridges. This is also the radial height of a tooth above

268-476: A contract is often an addendum to a contract and is simply referred to as being an extension or addition to a main contract. In today's business world additional authorisation subjects such as company seals are not usually required unless stipulated in the original agreement. It is to be distinguished from other appendices to a contract which may contain additional terms, specifications, provisions, standard forms or other information which have been separated out from

335-405: A limited subset of human languages. Unicode is an attempt to create a common standard for representing all known languages, and most known character sets are subsets of the very large Unicode character set. Although there are multiple character encodings available for Unicode, the most common is UTF-8 , which has the advantage of being backwards-compatible with ASCII; that is, every ASCII text file

402-489: A long and short form), and symbolic links between directories are also supported. Multics is the first to use the now-standard concept of per- process stacks in the kernel , with a separate stack for each security ring. It is also the first to have a command processor implemented as ordinary user code – an idea later used in the Unix shell . It is also one of the first written in a high-level language (Multics PL/I ), after

469-548: A matchbox", extends the Multics design to a networked graphics workstation environment. The Stratus VOS operating system of Stratus Computer (now Stratus Technologies ) is very strongly influenced by Multics, and both its external user interface and internal structure bear many close resemblances to the older project. The high-reliability, availability, and security features of Multics are extended in Stratus VOS to support

536-460: A much more versatile and flexible operating system, and it failed miserably". This position, however, is said to have been discredited in the computing community because many of Multics' technical innovations are used in modern commercial computing systems. The permanently resident kernel of Multics, a system derided in its day as being too large and complex, was 135 KB of code. The first MIT GE-645 had 512 kilowords of memory (2 MiB),

603-505: A new line of fault tolerant computer systems supporting secure, reliable transaction processing . Stratus VOS is the most directly related descendant of Multics still in active development and production usage today. General Motors ' Multiple Console Time Sharing System (MCTS) for the Control Data Corporation STAR-100 computer was based on Multics. The protection architecture of Multics, restricting

670-458: A process first attempts to begin execution in them. Since different processes can use different search rules , different users can end up using different versions of external routines. Equally importantly, with the appropriate settings in the Multics security facilities, the code in the other segment can gain access to data structures maintained in a different process. Dynamic linking in Multics does not require special dynamic-link libraries (DLLs) ;

737-449: A program can dynamically link to any executable segment to which it has access rights. Thus, to interact with an application running in part as a daemon (in another process), a user's process simply performs a normal procedure-call instruction to a code segment to which it had dynamically linked (a code segment that implemented some operation associated with the daemon). The code in that segment can then modify data maintained and used in

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804-456: A richer character set must be used. In many systems, this is chosen based on the default locale setting on the computer it is read on. Prior to UTF-8, this was traditionally single-byte encodings (such as ISO-8859-1 through ISO-8859-16 ) for European languages and wide character encodings for Asian languages. Because encodings necessarily have only a limited repertoire of characters, often very small, many are only usable to represent text in

871-418: A sizeable customer base. In contrast, the full potential of Multics’ flexibility for even mundane tasks was not easy to comprehend in that era and its features were generally outside the skill set of contemporary business analysts. The scope of this disconnect was concretized by an anecdote conveyed by Paul Stachour, CNO/CSC: When American Telephone and Telegraph was changing its name to just AT&T in 1983,

938-464: A staffer from Honeywell’s legal department showed up and asked a Multician if he could arrange to have the name changed in all of their computerized documents. When asked when the process could be completed, the Multician replied, "It's done." The staffer repeated that he needed hundreds perhaps thousands of documents updated. The Multician explained that he had executed a global search and replace as

1005-445: A sub-contractor) to develop a security kernel for Multics. This would involve reducing the size of the Multics hardcore by moving specific components of the supervisor out of Ring 0. One of the initial steps after carrying out a security evaluation was the implementation of a Multilevel security framework within Multics called AIM (Access Isolation Mechanism). This provided Mandatory access control which could be enabled to supplement

1072-428: A terminating newline character, normally LF. Additionally, POSIX defines a printable file as a text file whose characters are printable or space or backspace according to regional rules. This excludes most control characters, which are not printable. Prior to the advent of macOS , the classic Mac OS system regarded the content of a file (the data fork) to be a text file when its resource fork indicated that

1139-408: A text editor, human-readable content is presented to the user. This often consists of the file's plain text visible to the user. Depending on the application, control codes may be rendered either as literal instructions acted upon by the editor, or as visible escape characters that can be edited as plain text. Though there may be plain text in a text file, control characters within the file (especially

1206-416: A transcribed 2007 interview with Peter Seibel refers to Multics as "overdesigned and overbuilt and over everything. It was close to unusable. They [Massachusetts Institute of Technology] still claim it's a monstrous success, but it just clearly wasn't". On the influence of Multics on Unix, Thompson stated that "the things that I liked enough (about Multics) to actually take were the hierarchical file system and

1273-409: A truly enormous amount at the time, and the kernel used a moderate portion of Multics main memory. The entire system, including the operating system and the complex PL/I compiler , user commands, and subroutine libraries, consists of about 1500 source modules. These average roughly 200 lines of source code each, and compile to a total of roughly 4.5 MiB of procedure code, which was fairly large by

1340-414: A type of container, while plain text refers to a type of content. At a generic level of description, there are two kinds of computer files: text files and binary files . Because of their simplicity, text files are commonly used for storage of information. They avoid some of the problems encountered with other file formats, such as endianness , padding bytes, or differences in the number of bytes in

1407-609: Is also a UTF-8 text file with identical meaning. UTF-8 also has the advantage that it is easily auto-detectable . Thus, a common operating mode of UTF-8 capable software, when opening files of unknown encoding, is to try UTF-8 first and fall back to a locale dependent legacy encoding when it definitely is not UTF-8. On most operating systems, the name text file refers to a file format that allows only plain text content with very little formatting (e.g., no bold or italic types). Such files can be viewed and edited on text terminals or in simple text editors . Text files usually have

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1474-413: Is called by putting the active function name and the arguments to the active function in square brackets [ and ] . The string returned by the active function is substituted into the command in place of the call to the active function. For example, when the command echo [working_dir] is processed, the active function working_dir is run; it returns the full path of the working directory , which

1541-432: Is often used to add specific detail and especially specific conditions to a standard contract such as an insurance contract. A rider may also be added to a piece of legislation . Schedules and exhibits are sub-categories of addenda, with schedules being related to numerical and time information, such as pricing and time-schedules, and exhibits used for examples of standard forms or additional information necessary for

1608-400: Is one of the earliest multiprocessor systems. Multics is the first major operating system to be designed as a secure system from the outset. Despite this, early versions of Multics were compromised repeatedly. This led to further work that made the system more secure, and prefigured modern security engineering techniques. Break-ins became very rare once the second-generation hardware base

1675-433: Is part of some segment, which appears in the file system ; this includes the temporary scratch memory of the process, its kernel stack, etc. Segments are limited to 256 kilowords , just over 1  MB , because Multics hardware had 18-bit word addresses for the content of a segment. Larger files are "multisegment files" and are handled differently. The 256 kiloword limit was rarely encountered in practice, because at

1742-451: Is quite different, focusing on keeping the system small and simple, and so correcting some perceived deficiencies of Multics because of its high resource demands on the limited computer hardware of the time. The name Unix (originally Unics ) is itself a pun on Multics . The U in Unix is rumored to stand for uniplexed as opposed to the multiplexed of Multics, further underscoring

1809-434: Is substituted into the command, so that the echo command prints the working directory. Some programs can act either as commands or as active functions; when run as a command, its result is printed, and when run as an active function, its result is returned as a string. Some common active functions are: Peter H. Salus , author of a book covering Unix's early years, stated one position: "With Multics they tried to have

1876-423: Is used with a paper letter. Addenda are often used in standard form contracts to make changes or add specific detail. For example, an addendum might be added to a contract to change a date or add details as to delivery of goods or pricing. The addendum should be referenced in the contract, or the contract should be referenced in the addendum, so that it is clear which contract the addendum is modifying. A rider

1943-665: The Burroughs MCP system written in ESPOL , an expanded version of ALGOL . The deployment of Multics into secure computing environments also spurred the development of innovative supporting applications. In 1975, Morrie Gasser of MITRE Corporation developed a pronounceable random word generator to address password requirements of installations such as the Air Force Data Services Center (AFDSC) processing classified information. To avoid guessable passwords,

2010-474: The MIME type text/plain , usually with additional information indicating an encoding. DOS and Microsoft Windows use a common text file format, with each line of text separated by a two-character combination: carriage return (CR) and line feed (LF). It is common for the last line of text not to be terminated with a CR-LF marker, and many text editors (including Notepad ) do not automatically insert one on

2077-426: The classic Mac OS , and Windows, store text files as a sequence of bytes, with an end-of-line delimiter at the end of each line. Other operating systems, such as OpenVMS and OS/360 and its successors , have record-oriented filesystems , in which text files are stored as a sequence either of fixed-length records or of variable-length records with a record-length value in the record header. "Text file" refers to

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2144-449: The telephone and electricity utilities . Modular hardware structure and software architecture are used to achieve this. The system can grow in size by simply adding more of the appropriate resource, be it computing power, main memory, or disk storage. Separate access control lists on every file provide flexible information sharing, but complete privacy when needed. Multics has a number of standard mechanisms to allow engineers to analyze

2211-415: The 1.0 release of the emulator, and adds a few new features, including command line recall and editing using the video system. The following is a list of programs and commands for common computing tasks that are supported by the Multics command-line interface . The Multics shell language supports "active functions", which are similar to commands, but which return a string value. An active function

2278-559: The AFDSC decided to assign passwords but concluded the manual assignment required too much administrative overhead. Thus, a random word generator was researched and then developed in PL/I. Instead of being based on phonemes , the system employed phonemic segments (second order approximations of English) and other rules to enhance pronounceability and randomness, which was statistically modeled against other approaches. A descendant of this generator

2345-598: The United States. In 2006, Bull SAS released the source code of Multics versions MR10.2, MR11.0, MR12.0, MR12.1, MR12.2, MR12.3, MR12.4 & MR12.5 under a free software license. The last known Multics installation running natively on Honeywell hardware was shut down on October 30, 2000, at the Canadian Department of National Defence in Halifax, Nova Scotia, Canada. In 2006 Bull HN released

2412-412: The ability of code at one level of the system to access resources at another, was adopted as the basis for the security features of ICL 's VME operating system. The Edinburgh Multiple Access System (EMAS) draws particularly on the one-level store concept used by Multics, providing access to files only by mapping them into memory. All memory space is associated with a segment. The literature contains

2479-711: The already existing Discretionary access control that Multics already possessed. The resulting Project Guardian ran until termination in 1976; whilst most of its changes were not added to Multics, some parts of the project such as the proposed Secure Front End Processor was productized by Honeywell as SCOMP (Secure Communications Processor). The SCOMP and it's STOP operating system would eventually evolved via XTS-200 and XTS-300 into current XTS-400 offering of secure operating systems. Honeywell continued system development until 1985. About 80 multimillion-dollar sites were installed, at universities, industry, and government sites. The French university system had several installations in

2546-472: The daemon. When the action necessary to commence the request is completed, a simple procedure return instruction returns control of the user's process to the user's code. Multics also supports extremely aggressive on-line reconfiguration : central processing units , memory banks, disk drives, etc. can be added and removed while the system continues operating. At the MIT system, where most early software development

2613-407: The designers' rejections of Multics' complexity in favor of a more straightforward and workable approach for smaller computers. (Garfinkel and Abelson cite an alternative origin: Peter Neumann at Bell Labs, watching a demonstration of the prototype, suggested the pun name UNICS – pronounced " eunuchs " – as a "castrated Multics", although Dennis Ritchie is said to have denied this. ) Ken Thompson, in

2680-789: The early 1980s. After Honeywell stopped supporting Multics, users migrated to other systems, such as Unix. In 1985, Multics was issued certification as a B2 level secure operating system using the Trusted Computer System Evaluation Criteria from the National Computer Security Center (NCSC), a division of the NSA ; it was the first operating system evaluated to this level. Multics was distributed from 1975 to 2000 by Groupe Bull in Europe , and by Bull HN Information Systems Inc. in

2747-465: The end of a text file is denoted by placing one or more special characters, known as an end-of-file (EOF) marker, as padding after the last line in a text file. In modern operating systems such as DOS , Microsoft Windows and Unix-like systems, text files do not contain any special EOF character, because file systems on those operating systems keep track of the file size in bytes. Some operating systems, such as Multics , Unix-like systems, CP/M, DOS,

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2814-565: The end-of-file character) can render the plain text unseen by a particular method. Multics Multics (" MULTiplexed Information and Computing Service ") is an influential early time-sharing operating system based on the concept of a single-level memory . Nathan Gregory writes that Multics "has influenced all modern operating systems since, from microcomputers to mainframes." Initial planning and development for Multics started in 1964, in Cambridge, Massachusetts . Originally it

2881-502: The endianness of the file content. Although UTF-8 does not suffer from endianness problems, many Microsoft Windows programs (i.e. Notepad) prepend the contents of UTF-8-encoded files with BOM, to differentiate UTF-8 encoding from other 8-bit encodings. On Unix-like operating systems, text files format is precisely described: POSIX defines a text file as a file that contains characters organized into zero or more lines, where lines are sequences of zero or more non-newline characters plus

2948-400: The last line. On Microsoft Windows operating systems, a file is regarded as a text file if the suffix of the name of the file (the " filename extension ") is .txt . However, many other suffixes are used for text files with specific purposes. For example, source code for computer programs is usually kept in text files that have file name suffixes indicating the programming language in which

3015-408: The main body of the contract. These are called: an appendix (general term), an annex (which includes information, usually large texts or tables, which are independent stand-alone works which have been included in the contract, such as a tax table, or a large excerpt from a book), or an exhibit (often used in court cases), Similarly an attachment is used usually for e-mails, while an enclosure

3082-409: The parties to understand and/or comply with their contractual obligations. Outside of contract law, exhibits are often used in legal documents filed with a court as part of judicial proceedings such as motions, briefs and the submission of different types of evidence for inclusion in the record of trial of a particular case. Juries in inquests or trials may amplify or explain their decisions by issuing

3149-411: The performance of the system, as well as a number of adaptive performance optimization mechanisms. Due to its many novel and valuable ideas, Multics has had a significant influence on computer science despite its faults. Its most lasting effect on the computer industry was to inspire the creation of Unix, which carried forward many Multics features, but was able to run on less-expensive hardware. Unix

3216-401: The pitch circle. Text file A text file (sometimes spelled textfile ; an old alternative name is flat file ) is a kind of computer file that is structured as a sequence of lines of electronic text . A text file exists stored as data within a computer file system . In operating systems such as CP/M , where the operating system does not keep track of the file size in bytes,

3283-402: The process simply uses normal central processing unit (CPU) instructions, and the operating system takes care of making sure that all the modifications were saved to disk . In POSIX terminology, it is as if every file were mmap () ed; however, in Multics there is no concept of process memory , separate from the memory used to hold mapped-in files, as Unix has. All memory in the system

3350-404: The project in 1969 as it became clear it would not deliver a working system in the short term. Shortly thereafter, GE decided to exit the computer industry entirely and sold the division to Honeywell in 1970. Honeywell offered Multics commercially, but with limited success. Multics has numerous features intended to ensure high availability so that it would support a computing utility similar to

3417-479: The project in 1969; some of the people who had worked on it there went on to create the Unix system. Multics development continued at MIT and General Electric. At MIT in 1975, use of Multics was declining and did not recover by 1976 to prior levels. Finally by slashing prices, MIT managed to lure users back to Multics in 1978. In 1974 Honeywell entered into a development contract with the Air Force (with MIT as

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3484-467: The reader in interpretation. A text file may contain no data at all, which is a case of zero-byte file . The ASCII character set is the most common compatible subset of character sets for English-language text files, and is generally assumed to be the default file format in many situations. It covers American English, but for the British pound sign , the euro sign , or characters used outside English,

3551-425: The shell — a separate process that you can replace with some other process". Dennis Ritchie wrote that the design of UNIX was influenced by CTSS . The Prime Computer operating system, PRIMOS , was referred to as "Multics in a shoebox" by William Poduska , a founder of the company. Poduska later moved on to found Apollo Computer , whose AEGIS and later Domain/OS operating systems, sometimes called "Multics in

3618-414: The source code for MR12.5, the final 1992 Multics release, to MIT. Most of the system is now available as free software with the exception of some optional pieces such as TCP/IP . In 2014, Multics was successfully run on current hardware using an emulator created by Multicians Harry Reed and Charles Anthony. The 1.0 release of the emulator is available as of 2017 . Release 12.6f of Multics accompanies

3685-644: The source is written. Most Microsoft Windows text files use ANSI, OEM, Unicode or UTF-8 encoding. What Microsoft Windows terminology calls "ANSI encodings" are usually single-byte ISO/IEC 8859 encodings (i.e. ANSI in the Microsoft Notepad menus is really "System Code Page", non-Unicode, legacy encoding), except for in locales such as Chinese, Japanese and Korean that require double-byte character sets. ANSI encodings were traditionally used as default system locales within Microsoft Windows, before

3752-426: The staffer was speaking, and the task was in fact completed. The design and features of Multics influenced the Unix operating system, which was originally written by two Multics programmers, Ken Thompson and Dennis Ritchie . Influence of Multics on Unix is evident in many areas, including the hierarchical file system , redirection , the shell , and the naming of some commands. But the internal design philosophy

3819-434: The standards of the day. Multics compilers generally optimise more for code density than CPU performance, for example using small sub-routines called operators for short standard code sequences, which makes comparison of object code size with modern systems less useful. High code density is a good optimisation choice for Multics as a multi-user system with expensive main memory. During its commercial product history, it

3886-416: The time, one megabyte of memory was prohibitively expensive. Another major new idea of Multics was dynamic linking , in which a running process can make external routines available by adding the segments containing them to its address space. This allows applications to always use the latest version of any external routine, since those routines are kept in other segments, which are dynamically linked only when

3953-577: The transition to Unicode. By contrast, OEM encodings, also known as DOS code pages , were defined by IBM for use in the original IBM PC text mode display system. They typically include graphical and line-drawing characters common in DOS applications. "Unicode"-encoded Microsoft Windows text files contain text in UTF-16 Unicode Transformation Format. Such files normally begin with byte order mark (BOM), which communicates

4020-523: The type of the file was "TEXT". Lines of classic Mac OS text files are terminated with CR characters. Being a Unix-like system, macOS uses Unix format for text files. Uniform Type Identifier (UTI) used for text files in macOS is "public.plain-text"; additional, more specific UTIs are: "public.utf8-plain-text" for utf-8-encoded text, "public.utf16-external-plain-text" and "public.utf16-plain-text" for utf-16-encoded text and "com.apple.traditional-mac-plain-text" for classic Mac OS text files. When opened by

4087-446: The work, text files on a digital medium, or any similar carrier. It may serve to notify the reader of errors present, as errata . In other documents, most importantly in legal contracts , an addendum is an additional document not included in the main part of the contract. It is an ad hoc item, usually compiled and executed after the main document, which contains additional terms, obligations or information. An Additional Agreement to

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4154-532: Was a cooperative project led by MIT ( Project MAC with Fernando Corbató ) along with General Electric and Bell Labs . It was developed on the GE 645 computer, which was specially designed for it; the first one was delivered to MIT in January 1967. GE offered their earlier 635 systems with an early timesharing system known as "Mark I" and intended to offer the 645 with Multics as a larger successor. Bell withdrew from

4221-507: Was added to Multics during Project Guardian. In 1964, Multics was developed initially for the GE-645 mainframe, a 36-bit system. GE's computer business, including Multics, was taken over by Honeywell in 1970; around 1973, Multics was supported on the Honeywell 6180 machines, which included security improvements including hardware support for protection rings . Bell Labs pulled out of

4288-607: Was adopted; it has hardware support for ring-oriented security , a multilevel refinement of the concept of master mode . A US Air Force tiger team project tested Multics security in 1973 under the codeword ZARF. On 28 May 1997, the American National Security Agency declassified this use of the codeword ZARF. Multics is the first operating system to provide a hierarchical file system , and file names can be of almost arbitrary length and syntax. A given file or directory can have multiple names (typically

4355-540: Was developed at Bell to allow their Multics team to continue their research using smaller machines, first a PDP-7 and ultimately the PDP-11 . Multics implements a single-level store for data access, discarding the clear distinction between files (called segments in Multics) and process memory . The memory of a process consists solely of segments that were mapped into its address space . To read or write to them,

4422-477: Was done, it was common practice to split the multiprocessor system into two separate systems during off-hours by incrementally removing enough components to form a second working system, leaving the rest still running for the original logged-in users. System software development testing could be done on the second system, then the components of the second system were added back to the main user system, without ever having shut it down. Multics supports multiple CPUs; it

4489-555: Was often commented internally that the Honeywell Information Systems (HIS) (later Honeywell-Bull) sales and marketing staff were more familiar with and comfortable making the business case for Honeywell's other computer line, the DPS 6 running GCOS . The DPS-6 and GCOS was a well-regarded and reliable platform for inventory, accounting, word processing, and vertical market applications, such as banking, where it had

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