(MIT-XX) MASSACHUSETTS INSTITUTE OF TECHNOLOGY LABORATORY FOR COMPUTER SCIENCE (FUNCTION) SERVER COMPUTER: DEC-2060T HOST 0/IMP 44 MIT-XX is a research facility that offers researchers at the Laboratory for Computer Science computer time for ARPA related projects, including Dataflow machine architecture; interpersonal message systems; and CLU, an experimental structured programming language which provides support for the implementation and use of abstract data types. (ADDRESS) Massachusetts Institute of Technology Laboratory for Computer Science 545 Technology Square, Room 203 Cambridge, Massachusetts 02139 (PERSONNEL) PRINCIPAL-INVESTIGATORS Michael Hammer (Hammer@MIT-XX) (617) 253-5840 Barbara Liskov (Liskov@MIT-XX) (617) 253-5886 Albert Vezza (AV@MIT-XX) (617) 253-1450 MANAGER Albert Vezza (AV@MIT-XX) (617) 253-1450 LIAISON Michael Travers (MT@MIT-XX) (617) 253-1429 ACCOUNTS Janet Schoof (JAN@MIT-XX) (617) 253-1458 SOFTWARE-CONTACT Michael Travers (MT@MIT-XX) (617) 253-1429 HARDWARE-CONTACT Michael Travers (MT@MIT-XX) (617) 253-1429 OPERATOR There is currently no full-time operator. Computer room (617) 253-2910 (ACCOUNTING) CONTACT: Janet Schoof (JAN@MIT-XX) (617) 253-1458 Currently accounts are issued only to Laboratory for Computer Science researchers working on ARPA contracts. MIT-XX is not selling time to outside users. (SERVICE-SCHEDULE) MIT-XX is scheduled to be down for preventive maintenance alternating Thursdays 0600-1000 Eastern time. Pending downtimes are given at connect and logout time, and notification is automatically sent to active terminals well in advance of the actual shutdown. A list of all pending downtimes is available by typing: [@] information downtime TYPICAL LOAD = 15-25 users MAXIMUM NO. USERS = 100 NUMBER NETWORK SLOTS = 40 (LOGIN) TELNET INFO: . Appropriate echo mode = Character-at-a-time . Appropriate transmission mode = Full- or half-duplex; full-duplex is preferred. . To declare your terminal to the system, type: [@] terminal type TYPE . To see a list of all terminal types and settable modes, type: [@] terminal ? . To see what modes the terminal is currently set to, type: [@] information terminal . The default terminal type on initial network connection is NVT (Network Virtual Terminal) with remote echo, full-duplex. . The Local character set is ASCII and thus is the same as for the NVT (Network Virtual Terminal). . Both upper- and lower-case input is accepted, and a facility for translating lower-case characters to upper case, or flagging lower-case output, exists. . TIP settings - Transmit Each 1, Echo Remote LOGIN: Connect to MIT-XX, then type: [@] USERNAME PASSWORD SUBSYSTEM INTERRUPT = In most cases will suspend the current process and give control to the superior EXEC. SUBSYSTEM RESUME = [@] continue After suspending a process with the "continue" command will resume the process from where it left off. NOTE: "c" is a valid abbreviation for this command. SUBSYSTEM PROMPT CHARACTERS = : for CLU (LOGOUT) LOGOUT: [@] logout or [@] kkjob KKJOB is a fast version of LOGOUT since it will immediately detach the job from the terminal before actually logging out. AUTOLOGOUT: Not-logged-in jobs will be automatically killed after a few minutes. Logged-in users will eventually be logged out automatically if idle for a certain amount of time settable by the system staff, normally two hours if attached, or one hour if detached by the user. NOTE: Jobs which are detached by carrier loss, such as by hanging up the phone or disconnecting a net connection without logging out, will be logged out automatically after five minutes. (CONTROL-CHARACTERS) The function a control-character performs at any given instance is controlled by the current process tree, but several conventions are generally adhered to. The conventional control-characters are: Delete character Delete word Delete line Retype edited line Force recognition Interrupt Attention (prints a brief process status) Flush output (HELP) The standard conventions for asking for help from a command parser are to type a question mark ("?") to see a list of alternatives, or to issue the command "HELP" to the parser to see a short description of the more common options available and how to get more help. Note that the question mark can be imbedded in a keyword to view the alternatives matched so far. Also, (normally 33 octal) will complete a unique keyword. A complete list of available topics is shown by typing: [@] help * The device DOC: can be used to find subsystem or general documentation. To see a list of some of the online documentation available, type: [@] directory doc: (NETWORK-COMMANDS) (LIST-ACTIVE-USERS) Numerous commands and programs exist to obtain system status reports, FINGER and SYSTAT being the most commonly used. To see a list of all users logged into the system, type: [@] finger To get information on a specific user, USERNAME, type: [@] finger USERNAME NOTE: It is not necessary to log in to use either FINGER or SYSTAT. (NETWORK-STATUS) Both FINGER and SYSTAT will list the remote host a user is coming from, and LD will additionally list active connections related to users. To obtain a complete list of sockets and their states, type: [@] netstat (CONVERSE-WITH-ACTIVE-USERS) To converse with an active user in a real time conversation, type: [@] talk USERIDENT where USERIDENT can be the name of the user or else the octal terminal number obtained from SYSTAT or FINGER or the like. After acknowledgment is printed such as: [Link from Dang, TTY1] both input and output of a terminal will be echoed on the other linked terminal; but both terminals will be left with the same process listening to their own input as before. Thus, if at the command level an exclamation mark ("!") or a semicolon (";") should be used to make the EXEC ignore the typed line, e.g. [@]; Please feed the animals. The proper way to terminate a link is to issue the BYE command. [@]bye USERID where USERID can be the octal tty number of the terminal to end the link with, or else it can be the user name, or else it can be omitted entirely which will terminate all current links. (SEND-MESSAGE) To send a message which will appear on another logged-in user's terminal immediately, type: [@] send USERID MESSAGE Where USERID is the same as above. If the user is not logged in, or if sending mail is preferred, type: [@] sndmsg [To: ] USERNAMELIST [CC: ] USERNAMELIST [Subject: ] TEXT [Message (? for help):] TEXT [Q, s, or carriage return: ] For more details, give the command: [@] help sndmsg (RETRIEVE-MESSAGES) The system will inform a user of the arrival of new mail by typing a message such as: [You have new mail from Dang at 08:30] To read mail, the program MM should be used, which is documented in DOC:MM.DOC or type: [@] help mm Just a few related EXEC commands are: [@]information mail USERNAME (Checks if USERNAME has mail) [@]set mail-watch USERNAME (Watches USERNAME's mailbox) [@]set automatic (Will check for new mail every five minutes even if not at EXEC command level.) (TALK-TO-OPERATOR) Since there is no full-time operator coverage, the best way to report a bug, ask for assistance, or request for some action to be performed is to send a message to via the mechanism described under (SEND-MESSAGE). Alternatively, you may link to a user and ask for help. (FILE-NAMING) The syntax for a full file name looks like: DEVICE:FILENAME.EXTENSION.GENERATION-NUMBER; ATTRIBUTE where all fields are optional as long as enough exist to uniquely identify the file. See the write-up for SRI-KL for more details. (PROTOCOLS) (SERVER) PROTOCOL SOCKET (octal) DOCUMENTATION Telnet, Old 1 NIC 15372 etc. FTP* 3 NIC 17759 Echo 7 Systat 13 Time Server 15 Netstat 17 Telnet, New 27 NIC 18639 etc. Finger 117 NIC 42758 *FTP has been augmented with the XSEN and XSEM commands to allow remote users to send an immediate message to a local user (see NIC 42217). It also supports the XRSQ/XRCP mail extensions (see NIC 42752). (USER) User Telnet is available as TELNET for the new protocol and OTELNET for old protocol. Information about the program can be obtained by typing "help" to telnet. User FTP is available as FTP. Typing "help" to FTP will provide assistance. The Finger program will allow a remote finger to be done by adding in the host name preceded with an atsign ("@"). The /whois switch will give more information on specific users. (HARDWARE) (COMPUTER) TYPE MEMORY AMOUNT MEMORY SPEED WORD LENGTH DEC 2060T 2 megawords (MOS) MF20 36 bit (PERIPHERALS) HOW MANY TYPE MAKE MODEL DISKS 3 40 M 36 bit words DEC RP06 TAPES 2 9 track 1600 bpi DEC TU45A (TERMINALS) HOW MANY TYPE MAKE MODEL 1 printing DEC LA36 7 display DEC VT52 1 programmable DEC VT71 15 display DEC VT100 1 programmable HP 2645 1 programmable IMLAC PDS-1(D) 9 display Heath H19 (OPERATING-SYSTEM) Augmented TOPS-20 (USER-PROGRAMS) MIT-XX has the usual array of programs plus many interesting additions. To obtain an up-to-date list of the generally available programs type: [@] help subsys to the EXEC, or peruse the file HLP:SUBSYS. In any case, a few of the more unusual major subsystems are listed below. (CLU) TYPE: Language CONTACT: CLU@MIT-DMS Bob Scheifler (RWS@MIT-XX) (617) 253-1945 DESCRIPTION: CLU is an experimental structured programming language which provides support for the implementation and use of abstract data types. The current compiler does not type-check inter-file references. ACCESS: To compile a CLU program type: [@]clu FILENAME To run a CLU program type: [@]clusys [: ]load ("BINARY-FILENAME") [: ]PROCEDURE-NAME(ARG,ARG,ARG,...) [: ]... [: ]quit_() (_ = underscore) [@] DOCUMENTATION: 1. A Note on CLU, Computation Structures Group Memo 112 2. CLU Reference Manual 3. MIT-XX files: CLU.INFO (info on compiler) CLU.ORDER (compiler commands) CLUSYS.INTRO (introductory info) (MDL) TYPE: Language CONTACT: MDL@MIT-DMS DESCRIPTION: MDL is an interactive interpreter for the MDL language, which is similar to LISP but has more data types, more readable syntax, extensibility, flexible input/output (including the network), graphics, multiprocessing, and debugging facilities. A compiler and assembler are available. Facilities for putting generally-useful, documented programs in a library and for sharing compiled code are available. ACCESS: [@] mdl [mdl NNN in operation.] [...] [listening-at-level 1 process 1] ... (NOTE: '' must actually be typed as shown.) NOTE: MDL primitives are defined in upper case, so most input is normally in upper case; to have your input translated to upper case, type: [@] terminal raise DOCUMENTATION: 1. The MDL Programming Language, MIT/LCS Document 2. The MDL Programming Environment, MIT-DMS Document SYS.11.xx 3. MIT-DMS files: DSK: MUDMAN; * * (R) TYPE: Text Formatter CONTACT: R@MIT-DMS Eliot Moss (EBM@MIT-XX) (617) 253-5982 DESCRIPTION: R is a text formatter that produces output for printing devices and the Xerox Graphics Printer. (R is called R20 here, because "R" is already an EXEC command.) ACCESS: [@]r20 FILENAME [...] DOCUMENTATION 1. R Reference Manual 2. MIT-XX files: HLP:R.HLP (brief info) DOC:R20.MANUAL (reference manual) R.RECENT (recent info) RMACRO.INFO (info on standard macros) RMACRO.RECENT (recent info on macros) (INTERESTS) 1. Data base management We are developing several systems to enhance the efficiency, correctness, and usability of data bases. Among these are the following: . A system to automatically select a near-optimal physical file structure for a data base, based upon the pattern of the users' access to it and the characteristics of the data it contains. . A system that examines data submitted to a data base and determines its plausibility and legitimacy based on its agreement with a user-supplied model of the data base's problem domain. The key issue is the execution of a large set of potentially expensive validity tests in an efficient fashion. . A data error-correction system, which seeks to determine from an incorrect piece of data its original uncorrupted version, based on the characteristics of the faulty data and a model of the kinds of error mechanisms that can befall a datum. . A system to assist a user in interacting with a data base and formulating queries to it, by explaining its structure to him or her in problem-oriented terms. 2. Office automation We are exploring two issues in automated office systems: . The design of a problem-oriented specification language, in which to describe the function and organization of an office in non-procedural terms . The development of aids to the online decision-maker in an office environment, including such tools as an easy-to-use data base system, sophisticated alerter and monitoring functions, etc. 3. CLU system We are developing a system to support the use of data, procedural, and control abstractions in program design and implementation. The major components of this system are: . A compiler for the CLU programming language, an object-oriented language with complete compile-time type-checking . A run-time system for executing and debugging CLU programs . A system-maintained, system-wide library of all abstractions and their implementations 4. Message system We are developing a system for processing interpersonal messages in a completely automated way. This system has several components: . A clean and friendly user interface for reading, annotating, forwarding, composing, revising, and filing messages . A data base for storing messages for later recall and operations . An autonomous process for transmitting and receiving messages both locally and via the ARPANET via protocols under development . Means for ensuring security in all components (REFERENCES) Most non-DEC documentation is available online in DOC:. To obtain a list of available documentation type: [@]dir doc: For descriptions of research projects, see: . MIT Laboratory for Computer Science Progress Reports . "The Semantic Data Model: A Modelling Mechanism for Database Applications", by M. Hammer and D. J. McLeod, in Proceedings of 1978 ACM SIGMOD International Conference on Management of Data, Austin, Texas, May 31 - June 2, 1978. . "Research Directions in Database Management", by M. Hammer, in P. Wegner (ed.), Research Directions in Software Technology, MIT Press, Cambridge, Mass., 1979. . "Design and Implementation of Office Information Systems", by M. Hammer and M. D. Zisman, in Proceedings of the NYU Symposium on Automated Office Systems, New York, N.Y., May 17-18, 1978. . "Abstraction Mechanisms in CLU", by Liskov et al, Comm. ACM vol 20, no 8 (August 1977), pp. 564-576. . "CLU Reference Manual", by Liskov et al, MIT/LCS/TR-225, October 1979. . "An Electronic Message System: Where does it fit?" by Vezza and Broos, in "Trends and applications 1976: Computer Networks" (IEEE), pp. 89-97. (ORDER-INFORMATION) DEC manuals can be ordered directly from Digital Equipment Corp. MIT-XX documents may be ordered from Janet Schoof (JAN@MIT-XX) (617) 253-1458.