\chapter{RSX-11 Operating Characeristics} \label{RSX-11 Operating Characeristics} \section{Startup} RSX-11 systems support all of the standard TECO invocation commands, namely \begin{verbatim} TECO TECO filespec TECO filespec=filespec MAKE filespec MUNG filespec MUNG filespec,text \end{verbatim} If any of these commands are not recognized by the system, check with your system manager to see that TECO is properly installed. TECO macros may also be invoked with the command \begin{verbatim} TECO @filespec \end{verbatim} It is exactly equivalent to \begin{verbatim} MUNG filespec \end{verbatim} In systems supporting dynamic task expansion, TECO will expand its buffer space as necessary. Also, TECO'S buffer space may be explicitly allocated in the startup command \begin{verbatim} RUN $TEC/INC=n \end{verbatim} \section{Initialization} TECO searches for the TECO.INI startup file in the current default device and directory. TECO's memory, in which a plain TECO command edits the file last edited with a TECO filespec or a MAKE filespec command, is implemented with a file named TECF00.TMP, also stored in the current default device and directory. The initial value of the ED flag is always 1. When TECO is initially invoked it will automatically set the ET and EU flags according to the user's terminal characteristics. If the terminal supports CRT style rubouts, then bit 1 of the ET flag is set to do the same in TECO. If the terminal supports lower case type in, then bit 2 of the ET flag is set and the EU flag is set to -1 to turn off case flagging. If the terminal is a CRT type terminal and the version of TECO includes the screen support package, then bit 9 of the ET flag is set. While the command line is being processed, bit 7 of the ET flag is also set to cause TECO to exit should any errors occurr. ET bit 7 is cleared every time TECO reaches prompt (*) level. \section{File Specification} The file access commands {\tt ER}, {\tt EB}, {\tt EW}, and {\tt EI} accept a file specification in the standard RSX-11 format: \begin{verbatim} dev:[p,pn]filename.typ;version \end{verbatim} in which {\tt dev:} is a physical device name or a logical device name; if {\tt dev:} is not specified, {\tt SY:} is assumed. If {\tt [p,pn]} is not specified, the user's current default directory is assumed. The filename field must be specified whenever the device name references a file structured device. The typ field is a file type and must be explicitly given if used. There is no default type except for {\tt EI} commands which default the {\tt .typ} field to {\tt .TEC}. The {\tt /B2} file specification switch may be applied to the {\tt ER}, {\tt EW}, and {\tt EB} commands and invokes special handling of program lines containing {\tt \&} continuation characters. See Appendix \ref{BASIC-PLUS/BASIC-PLUS-2 Handling} for more information. The switch {\tt /RW} may be applied to any file specification in an {\tt ER}, {\tt EW}, and {\tt EI} command. If the file specification references a magtape, the tape is rewound before the file is opened. Note that for output files, this has the effect of zeroing the tape. The {\tt /RW} switch is ignored for all other device types. The presence of version numbers in Files-11 causes file processing to behave slightly differently under RSX-11 than under other operating systems. For example, no {\tt .BAK} files are used; each execution of an {\tt EB} command simply produces a new version of the file. Thus a user may retain any level of backup he feels to be comfortable. It also means that one must occasionally delete obsolete files to avoid cluttering the disk. Thus the command \begin{verbatim} EBname.typ;version` \end{verbatim} is equivalent to the commands \begin{verbatim} ERname.typ;version`EWname.typ;0` \end{verbatim} The {\tt EW} command also creates a new version (one higher than the current highest) if no version number is given. If an explicit version number is given, then that number is used, and if another file of the same name, type, and version previously existed, it is superseded without warning. (See use of the {\tt EP} and {\tt EK} commands below.) In reading files, version numbers behave the same as in other RSX-11 utilities: the default is the highest version. This leads to a problem in re-opening the input file while a file is being edited with {\tt EB}. Since the output file is already created and in the directory, the input file is no longer the highest version. One may deduce the version number of the input file by doing a {\tt :G*} (typing the file string of the output file) and subtracting one from that version number. In symmetry with the {\tt EB} command, the {\tt EK} command functions by simply deleting the current output file. Note, however, that a supersede ({\tt EW} of same name, type, and version) is not undone - the file is already deleted! The {\tt EP} and {\tt EA} commands, while simulating two channels each with an open file for each of input and output, in fact only keep one file open for each to conserve buffer space. This means that they are only useful for disk files. Also, it means that if you open a file and then supersede it, you should not switch the input channel away from it with an {\tt EP} or {\tt ER}\escape command, since it will not be possible to open the file again. \section{Wild Card Lookup} The {\tt EN} command will process wild card lookups on RSX-11. To preset the wild card lookup file specification, use the standard RSX-11 format \begin{verbatim} dev:[p,pn]filename.typ;version \end{verbatim} The device name must reference a file structured disk device or magtape. All other fields of the file specification may be fully wild ({\tt *}), including either or both halves of the directory. The version number may be explicit, wild, or default. As with the other file specification commands, there is no default file type. \section{Exiting From Teco} The normal method of exiting from TECO is with the {\tt EX} command. This copies the remaining input file to the output file, closes all files and exits. The \fbox{CTRL/C} (or Caret-C) command is the "give up and get out" command. Executed from main command level, it will cause TECO to exit regardless of the state of the buffer. If there is an open output file, it is deleted. The \fbox{CTRL/C} command is roughly equivalent to {\tt EKHKEX}. \section{CTRL/C} \label{CTRL/C} The action taken when the user types \fbox{CTRL/C} depends on what TECO is doing. If TECO is executing commands, or is awaiting type-in for the \caret{\tt T} command, the {\tt ?XAB} error occurs. If TECO is at command level, typing \fbox{CTRL/C} cancels the command string currently being typed and returns TECO to its prompt. Two consecutive \fbox{CTRL/C} characters will cause an instant {\tt HKEKEX} exit. Sometimes it is desireable for a TECO macro to detect when a \fbox{CTRL/C} was typed. By detecting the \fbox{CTRL/C}, the macro can exit cleanly back to command level (pop saved Q-registers, restore any flag values, etc.). To do this, the macro sets Bit 15 (Octal 100000, Decimal -32768) of the ET flag. When a \fbox{CTRL/C} is typed, TECO will automatically turn off Bit 15, but will continue execution of the macro. The macro periodically checks Bit 15 and exits cleanly if it ever goes off. For example: \begin{verbatim} [0 [1 -32768#ETET < ... ET; > 32767&ETET ]1 ]0 \end{verbatim} Setting the CTRL/C intercept bit in the ET flag must be done with some care; if the bit is set inside a command loop which does not check it, it will be impossible for the user to abort the loop. The only remedy for this situation is to abort TECO from another terminal. \section{Exit And Go} If TECO is exited via the {\tt EGstring}\escape command, TECO closes its files and exits. It then causes {\tt string} to be executed as an {\tt MCR} command using the spawn system directive. This feature works only on RSX-11M V3.2 and RSX-11M+ V1 or later. \section{ET Flag Handling} TECO will automatically turn off the following bits in the ET flag on every error: Bit 0 (image output), Bit 3 (no echo on \caret{\tt T}), Bit 4 (cancel \caret{\tt O}), Bit 5 (no stall on \caret{\tt T}), and Bit 15 (\caret{\tt C} trap). In addition, TECO always turns off Bit 7 (exit on error, etc.) every time is reaches prompt (*) level. Bit 6 (the detach flag) controls TECO'S treatment of the terminal. Normally, TECO keeps the terminal attached to gain control of \fbox{CTRL/C} interrupts. Setting bit 6 of the ET flag causes TECO to run with the terminal detached. All commands function normally, except that typing \fbox{}, {\tt }, {\tt }, {\tt } (vertical tab), or {\tt }. A record ending in form feed is interpreted as an end of page mark; it stops the read operation and the form feed is not entered in the buffer. If the file has print file carriage control, TECO interprets the carriage control bytes and inserts the resulting carriage return and line feed characters about the record. If the input file has no carriage control (also called internal carriage control), TECO simply packs the records together in the text buffer. On output, TECO scans the text buffer for carriage return, line feed, vertical tab, and form feed characters. Each such character delimits the end of an output record. If the output file is implied or Fortran carriage control, and the record ends with exactly carriage return / line feed, the carriage return and line feed are not output with the record; Otherwise, the record is output in its entirety. The carriage return and line feed are also output with the record if the record ends with ESCAPE / carriage return / line feed. Switches may be applied to the input and output files to control their carriage control attributes. The switch {\tt /CR} forces implied carriage control; {\tt /-CR} forces no (internal) carriage control; {\tt /FT} forces Fortran carriage control. When a carriage control switch is applied to an input file, the file is read as if it had that attribute; when the switch is applied to an output file, the file is written with that attribute. Applying a switch to an {\tt EB} file specification causes the switch to apply to both input and output files. When an output file is created, its carriage control attributes are defaulted to those of the currently open input file as follows: \begin{minipage}[t]{3.5in} \begin{tabular}{ll} Input & Output \\ & \\ implied & implied \\ none & implied \\ FORTRAN & FORTRAN \\ print file & implied \\ \end{tabular} \end{minipage} Files read with the {\tt EI} command have their record attributes interpreted in the same manner. This leads to an unexpected side effect with {\tt EI} files containing an entire command. The last record of the file presumably contains as its last characters the two alt modes which initiate execution of the macro. If the file is implied carriage control, however, there are also the final carriage return / line feed belonging to the last record, which remain in the type in buffer while the macro executes. If the macro attempts to receive input with the {\tt } command, the carriage return / line feed will be the first two characters read. Alternatively, if the macro does no type in, the carriage return / line feed will be read by TECO as the first two characters of the next command. Then no asterisk ({\tt *}) will appear as the prompt for the next command. The remedy for both cases is for the macro to execute an {\tt EI}\escape command early on. This causes the remainder of the indirect file to be discarded and further input to be read from the terminal. \section{Command Line Processing} \label{Command Line Processing} The mechanism used to process the command line in RSX-11 TECO is designed to allow sophisticated TECO users the greatest flexibility in customizing TECO for their own use. It functions as follows: The initialization routine places the original {\tt MCR} command line (if any) into the filename buffer. It copies into the text buffer the text of a TECO macro that will be used to interpret the command line. Then it starts up TECO with the command \begin{verbatim} HXY HKG* HXZ HK :EITECO\escape\escape \end{verbatim} in the type in buffer. This loads the command line into Q-register Z and the macro into Q-register Y. It then executes the file named {\tt TECO.TEC} located in the user's default directory, if it exists. After the user's {\tt TECO.TEC}, and any files it might link to with {\tt EI}, have been executed, TECO executes the command {\tt MY}\escape\escape, thus executing the macro to interpret the command line and open the files requested. The {\tt TECO.TEC} mechanism should not be used for simple initialization; the standard {\tt TECO.INI} facility should suffice for that. The alternate {\tt TECO.TEC} facility is provided for the sophisticated user who wants his own command processing and thus wishes to usurp control from the normal initialization. If an {\tt EI}\escape command (to close the indirect command file) is executed during the processing of a user's {\tt TECO.TEC} startup file, the final {\tt MY}\escape\escape which causes processing of the command line is not executed. This results from the fact that the {\tt MY}\escape\escape normally appears in TECO's type in after all command files have been processed. Executing the {\tt EI}\escape command causes all ``type ahead'' to be discarded to allow a TECO command file to prompt and read input from the terminal (and not read extraneous type ahead). It is assumed that a TECO startup file that executes {\tt EI}\escape and reads input from the terminal will want to manage the rest of TECO's startup. If it still wants to process the command line, it must issue the {\tt MY} itself.