xmt - intercomputer communications task 12-Jan-82 Overview -------- XMT is a utility task which provides a convenient means for data transfer between the the Medical Physics PDP11 and any other com- puter system that is accessible with a standard terminal by ei- ther hard-wired lines or by dial-up modem. XMT makes your termi- nal appear as though it were connected directly to the "remote" computer system. Data transfer is performed by producing textual output from the remote computer (e.g., program listings, computer runs, etc.) and, through XMT, routing that text to a disk file at the PDP11. The reverse path takes a file at the PDP11 and "types" it to the remote. 12-Jan-82 CHAPTER 1 Using XMT XMT is a standard MCR function, evoked by: MCR>XMT XMT prints the message: Terminal Transmission Program V3.3 Initializing operation using TT25: If TT25 is connected to a dial-up modem you must now dial the re- mote computer before continuing. If the terminal is hardwired to the remote system, or when you have made the connection to the remote via modem, XMT is ready for operation. XMT is now running with several defaults in effect: 1. ASCII transfer mode. XMT expects files to be in ASCII format, (i.e. source, listings, etc.) 2. COPY mode is off. When receiving a "file" from the remote terminal, char- acters typed at your terminal are not echoed to the out- put file. 3. DELAY of 20 milliseconds. XMT will wait 20 milliseconds after receiving a "prompt" character from the remote terminal, (usually a line-feed) before transmitting the next line of a file to the remote computer. 4. ECHO Mode is off. When file transfer is in process, all I/O is not printed on your terminal. A single flag character is printed for each line transferred. 5. PROMPTED transmission is on. XMT waits for a Line-Feed (or some other character) be- fore transmitting the next line of a file from the PDP11 to the remote computer. Using XMT PAGE 1-2 12-Jan-82 6. Several control characters are re-defined (see appendix) Since ^C is used to inform XMT that you wish to change some operating condition, if you wish to send a ^C to the remote computer, typing a ^B will cause a ^C to be sent to the remote computer. Note that although several other re-defines are normally set, under IAS, only the ^C re-define is necessary. 7. FULLDUPLEX mode is on Characters typed at your terminal are not echoed local- ly, the remote computer must echo them. 8. 8-BIT ASCII mode is off, no parity Characters are transmitted with 7 data bits and the par- ity bit off. These settings can be changed dynamically by the user to tailor XMT's characteristics to ease communication with other computers. This version of XMT has been modified for IAS (basically a rewrite of the terminal I/O sections) by G. Everhart. In normal operation, it uses TT25 for connection to the "remote" computer. TT25 should normally be set up at system boot, but if necessary one may have to reset it to: MCR>SET /UIC=[1,1] ;To change another Terminal setting MCR>TER TT25:/FULLDUPLEX ;fix for no echo, full duplex I/O MCR>TER TT25:/BINARY ;fix for no special ^C recognition MCR>TER TT25:/WIDTH:132 ;make width big enough This should allow the terminal to work correctly. Note that you'll have to try various options when using it with non-DEC systems. In its default state, it works well with other IAS or RSX11M systems. You will have to reset the characterstics of TT25 to permit someone to connect a terminal to it and have it work correctly. Also, by the nature of the program, (it uses single-character QIO's for I/O to your terminal) will sometimes result in a noticable delay in output (or echo) at your terminal. However, it appears to work reliably once the right operating conditions and defaults are established. To leave XMT, type CTRL/C twice (CTRL/C is typed by holding down the CTRL key and typing C), or by typing CTRL/C followed by X (eXit). 12-Jan-82 CHAPTER 2 XMT Options To change any of the program settings/options, type CTRL/C fol- lowed by the upper case character signifying the setting/option desired. Below is a table of options and their corresponding de- finitions: NOTE Do NOT type a carriage-return to enter or execute any of these commands. Typing the single character of the com- mand is all that you need to execute that option. A - Changes the file transfer mode to ASCII if in the binary mode, or changes the file transfer mode to binary if al- ready in the ASCII mode. B - Sets the BREAK (logical spacing) key definition to some keyboard character which, when depressed, creates a 'BREAK' condition to occur just like the 'BREAK' key on a teletype. C - Enter/exit Copy mode; i.e., when receiving a file from the remote in ASCII mode, all characters typed at the keyboard are copied to the output file when also in Copy mode. D - Set the length of delay that XMT should wait after re- ceiving a prompt character before sending the next line of data from a disk file at the PDP11. The delay can range from 0 to 99, where 0 corresponds to no delay and 99 corresponds to 99 clock ticks (approximately 1 2/3 seconds). If the length of the delay is a single digit, typing a carriage-return after typing the digit will be sufficient to enter the delay. You may also enter a single digit for the delay by preceeding it with a zero. You cannot enter a delay of more than two digits. Any characters entered other than 0 through 9 will cause the default delay of 20 to be used and no error message will XMT Options PAGE 2-2 12-Jan-82 be given. E - Enter/exit Echo mode; i.e., when receiving or transmit- ting a file all input/output from/to the PDP11 disk is printed on the user terminal. This mode is useful when you wish to see the effects of transmission in progress. In general, this mode should only be used when you are logged onto a high-speed terminal or when the amount of printing is less than 2 full pages (at 1200 baud) or in- definitely (at 300 baud or less). F - Receive a file From the remote. A short status of the applicable options in effect is printed before a file specification is requested. The file specification is 29 or fewer characters and follows the system standard conventions for files. Entering a name of less than 29 characters requires a carriage-return to enter the fi- lename. The RUBOUT or DELETE keys can be used to edit out any errors made in typing the file spec. Entry of a null, or empty, filename will allow you to exit the F option without sending any data or creating any files. Any previous execution of the F option that was not ter- minated by either the O option or by exitting XMT is au- tomatically terminated prior to the printing of the short options-in-effect summary. H - Prints a very brief Help summary of the purpose of each option. I - Terminates reading input from a PDP11 disk file if such a file transfer was taking place. The message "Transmission Complete" will be printed if a file transfer is terminated, otherwise no action is taken. This option is useful in aborting the transmission of data to the remote if problems in communication arise. O - The O option performs the same function for terminating a file receive operation (Output to the PDP11 disk) that the I option performs on file transmit operations (Input from the PDP11 disk). This option is the only means, other than by exitting XMT or by starting another file receive operation, of signalling the end of a receive operation to XMT. The message "Receive complete" prints when a receive operation is terminated. P - Change transmit file mode from Prompted mode to Prompt- less, and vice-versa. A message is printed indicating which mode is in effect. When changing to prompted mode you are asked which character sent by the remote com- puter system should be used as the prompting character. Type the prompting character and XMT will, during a file transmit operation, wait for this character to be re- ceived from the remote computer before sending the next XMT Options PAGE 2-3 12-Jan-82 line of information to the remote. Note that XMT will send the first line of input to the remote computer without waiting for the prompt, but all other lines of input will wait for a prompt to be received before they will be sent. R - Redefine/don't redefine control characters. This option enables and disables the user-defined translation table for control characters as described under the "^" op- tion. A message is printed which mode is in effect. When in "Redefine mode" XMT will use a translation table to convert any redefined control characters to some oth- er control character so as to be able to "type" reserved control characters to the remote computer. Examples of reserved control characters are CTRL/C, CTRL/O, CTRL/S, CTRL/Q, etc. "Not redefined mode" disables this trans- lation, but the translation table is not destroyed. S - Prints a Status of the options in effect for XMT. The status report includes information about parity, ASCII or binary modes, information about file transfer opera- tions, and prints the definition of the BREAK character, if any. T - Starts a file Transmit operation. This option is very similar to the F option except in the direction of data transfer. A check is made as to whether or not XMT was in the midst of a previously started file transmit oper- ation, and if so, that transmit operation is terminated. A short status of file transmit options-in-effect is printed before you are requested to type in the name of the file you wish to transfer to the remote system. If you just type a carriage-return, XMT simply returns without initiating a file transfer. Otherwise you must enter a file name in the standard system format. If the name of the file you enter does exist on disk a message is printed indicating that the file is not found and no transfer operation is initiated. Otherwise a file transfer is initiated which can be terminated by 1) ex- itting XMT, 2) using the I option, 3) using the T option again and entering a carriage-return for the name, or by 4) reaching the end of the input file. The message "Transmission complete" is printed when the transfer op- eration is completed (or terminated). U - Unduplex or duplex the XMT program. In the Unduplexed mode characters typed on the terminal are not echoed to the terminal unless the remote computer performs the echoing. This mode is useful when communicating to com- puter systems as other PDP11's. For communication with systems such as TSO, however, the Duplexed mode is re- quired if you wish to see the characters that you type. XMT Options PAGE 2-4 12-Jan-82 X - EXit XMT. All file transfers, if any, are terminated and control is returned to the RSX-11M Executive. 8 - Enter 8-bit ASCII mode and exit 7-bit ASCII, or leave 8-bit ASCII and enter 7-bit ASCII and be asked what par- ity you desire. This mode allows you to determine whether or not the information you transmit and receive will be full 8-bit ASCII or 7-bit ASCII with software generated even, odd, mark, or no parity. Some computer systems require specific parity settings, but other PDP11's and TSO don't care. ^ - Allows you to redefine a control character as a differ- ent control character. This allows you to use some oth- erwise reserved control characters, such as CTRL/C, and allow you to send these characters to the remote system. You will be asked to type two characters. The first character you type will be the redefined character and the second character you type will be the definition. To enter either of these characters may, and sometimes must, enter the upper-case equivalent of the control character. The characters you type are automatically converted to the proper control character and their upper-case equivalent is printed after you type the character. For example, you wish to use the character CTRL/W to signal when you transmit a CTRL/C. Type the ^ option, the letter W, and the letter C and the redefini- tion has been set. Assuming that XMT is in "Redefine mode", every time you type a CTRL/W a CTRL/C is actually sent to the remote system. If you wish to change a de- finition, simply redefine it in the manner given above. 12-Jan-82 CHAPTER 3 Summary of Capabilities 1. Full or half duplex operation 2. Disk file transmit and receive 3. Prompt character checking and delay 4. Optional echoing of files during transmission and recep- tion 5. A short help message summary 6. The ability to transmit a file while also receiving another file 7. The ability to transfer files using a full 8 bits 8. The capability of transferring files with or without prompted handshaking 9. The option of preventing everything entered at the user terminal from being copied to an output disk file during a receive operation 10. The ability to create a 'BREAK', or logical spacing, condition so as to be able to interrupt remote devices such as TSO 11. The capability of defining almost any keyboard character to be used to signal when a BREAK was desired 12. The ability to perform translations of control char- acters entered at the user terminal to characters not normally able to be entered without interception by RSX-11M 13. The ability to turn on and off the control character translation without losing the previous definitions 14. The inclusion of a "status" subroutine which enables the Summary of Capabilities PAGE 3-2 12-Jan-82 user to see what parameters are currently in effect for the program 15. The ability to set the mode of parity (even, odd, mark, or none) to be used when transmitting each character to the remote while the 7-bit character mode is in effect. 12-Jan-82 APPENDIX A XMT Default Control Character Definitions Typed Character Resulting Character ctrl/A ctrl/S ctrl/B ctrl/C ctrl/P ctrl/O ctrl/W ctrl/Q ctrl/X ctrl/Z List of XMT commands A - Change file transfer mode (Binary/Ascii) B - Set BREAK character C - Enter/exit copy mode D - Set length of delay (in ticks) E - Enter/exit echo mode F - Recieve File from remote computer H - Prints HELP summary I - Terminate transmission to remote computer O - Terminate reception from remote computer P - Enter/exit Prompted transmission mode R - Redefine/don't redefine control chararacter mode S - Print current program status T - Transmit file to remote computer U - Enter/exit full duplex mode X - Exit XMT 8 - Enter/exit 8-bit ASCII mode ^ - Redefine control character