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Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 31 7.20 Strange Modems Most intelligent modems can be commanded to autodial with a suitable mprefix and msuffix string. Those modems that won't work with a particular mprefix can be programmed with a custom "dial" script. If the modem can be configured to reset to a known condition when DTR is turned off, programming is usually straightforward. Otherwise, the script must determine what speed the modem is set to, and then, at its present speed, command the modem to change to the desired speed. The essential requirement is to write a script that controls the modem and responds to its state. The information on scripts in Chapter 99 should prove useful. 7.21 Manual Dialing with Smart Modems Some hotels and exotic locales sport telephone systems with unusual dialing requirements. It may be necessary to dial the call with the telephone, talk to an operator, and then activate the modem. With Hayes compatible modems, an ATD command may be given to the modem to connect it to the line and attempt a data handshake. 7.22 Direct Connection ZCOMM works well communicating with locally connected microcomputers, minicomputers, or mainframes with direct RS-232 connections. For such applications, only transmit and receive data data lines need be connected to the computer. The Carrier Detect line[5] should be driven ON (+5 volts) to prevent noise on this line by strapping it to Data Terminal Ready [6] if no other signal is available. For best high speed operation, replace 8250 or 16450 UART chips with the NS16550AN chip. ZCOMM enables the hardware buffering on this chip to avoid data loss caused by TSR programs, special device drivers, extended memory disks or caches, and DOS clock interrupts. __________ 5. Pin 8 on 25 pin RS-232 connector, pin 1 on PC-AT 9 pin connector. 6. Pin 20 on RS-232 connector, pin 4 on PC-AT 9 pin connector. (C) 1989 Omen Tech Inc Chapter 7 Your Telephone Directory Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 32 8. YOUR TELEPHONE DIRECTORY ZCOMM's telephone directory is a big flexibility advantage over traditional communications programs which require one or more separate files for each system called, or limit directory information to little more than a telephone number. The telephone directory is a plain ASCII text file which can be edited with standard text editors (brief, teco, EMACS, edlin, etc.). Normally, ZCOMM expects to find the telephone directory in the file /PHODIR.t on the current disk. The pathname may be changed with the PHONES environment variable. Forward slashes should be used to indicate directories. EXAMPLE: C>set PHONES=c:/yam/lib/PHODIR.t EXAMPLE: $ PHONES=/u/flashg/bin/phones.t; export PHONES (for Unix) The putsnp program may also be used to change ZCOMM's default Telephone Directory pathname. The call command connects to another computer. When you give a call name command, ZCOMM prepares for a modem call and then searches the telephone directory file for a line starting with name. It is not necessary to type the entire name as it appears in the file. ZCOMM will find the first entry that name is a prefix of. EXAMPLE: call cis would access either the cis300 or cis1200 telephone directory entry, whichever was first. When using two entries with similar names (such as "cis300" and "cis1200"), place the favorite entry first. This way you can just type call cis to get the desired entry. If the search is successful, the call command copies the complete directory entry name to the remote string parameter, where it can be used for log entries and automatic password generation. ZCOMM executes the commands on the rest of the line (if any), and on succeeding lines beginning with a space or tab, until the next Telephone Directory entry or a return command is seen. There is no arbitrary limit to the size of the telephone directory. Popular entries may be placed near the front to minimize searching time. When desired, Scripts can be placed in separate files referenced with a source command from the Telephone Directory entry. (C) 1989 Omen Tech Inc Chapter 8 Your Telephone Directory Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 33 8.1 Customizing Your Telephone Directory 8.1.1 TAKE A SHORTCUT WITH PHOMAST.T This starter script was written by Michael Ash of San Antonio, Texas. It is easy to configure and use by following the detailed instructions included in the file itself. 8.1.2 CUSTOMIZING PHONES.T Compared to phomast.t, phones.t is the "industrial strength" prototype directory. While not as easy to configure as phomast.t, it is powerful enough to tame a TrailBlazer and other complex modems. When ZCOMM begins execution, it searches the telephone directory for the setup entry. (A directory entry has the entry name starting at the left margin.) The setup telephone directory in the distributed phodir.t file invokes a demonstration menu. Once you have exercized the various demonstration possibilities, search for the xsetup telephone directory and change it to setup be removing the "x". This will blank out the oroginal setup entry which appears later in the file. setup port 1 The first line of the "setup" entry selects port 1. : if !c speed 1200 putw "ATZ\r" This line is commented out with a colon (:). If the colon is removed, the speed is changed to 1200 and ZCOMM sends an initialization command to the modem if no carrier detect signal is present. If a carrier detect signal is present (modem still connected to the remote computer), the speed is not changed, and no initialization command is sent to the modem. pd1; pz480 enables incoming time/date information provided by the ZMODEM and True YMODEM protocols. Time/date stamping of transmitted files provides many advantages over traditional protocols, including the ability to selectively transmit files if the source file is newer than receiver's copy. The number in the pz480 command should represent the local time zone expressed as minutes behind GMT.[1] This line should be commented out with a leading colon (or removed) if __________ 1. Pacific Standard Time is 480 minutes behind Greenwich Mean Time (C) 1989 Omen Tech Inc Chapter 8 Your Telephone Directory Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 34 you use a backup program that depends on the dates of files to determine which to save. set mprefix "ATDP" sets the string parameter mprefix to ATDP, setting the Hayes modem to use rotary (pulse) dialing. If your phone uses tone dialing, comment that line out (place a leading colon to make ZCOMM pass over it) and uncomment the line containig "ATDT". set l "1"; set m "1" The l and m string parameters support the dynamic selection of one or more ALDS alternate long distance carriers. The default values for these parameters is the digit 1. When making entries in your telephone directory, use %l- for numbers with different area codes, and %m- for numbers with the same area code as yours. If you use a long distance credit card or sometimes dial out from hotel or PBX lines, be sure to modify the att, ddd, hotel9, and hotel8 telephone directory entries in phones.t to suit your needs. The set command sets the string parameter l (lower case L) to 1 (number), providing for normal long distance access. If you have an alternative long distance service, set this parameter to the required access string for that service.[2] The "set m 1" command sets the string parameter m to 1, providing for normal long distance access for numbers in your same area code. If you have an alternative long distance service, set this parameter to the required access string for that service, plus your area code if required. (Some alternate long distance services require the area code for all calls, even those in your own area code.) set answerback "YOUR NAME CITY\r\n\21" Change the answerback setting to reflect your name.[3] Be sure to keep the \21 at the end of the string.[4] The next lines configure soft keys F3 to FS4. Their functions are __________ 2. Use the "setsavenet" entry in PHODIR.t as a prototype. 3. Some timesharing systems may require a specific answerback string. 4. See Chapter 23 for a description character escapes. (C) 1989 Omen Tech Inc Chapter 8 Your Telephone Directory Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 35 described at the end of Chapter 15. : display bell=visual Causes bell characters to be displayed as a flashing musical note instead of sounding. If you want a silent bell, uncomment this line. set quitcmd "\003\336off\r" This string is sent to the remote before disconnecting when an ALT-Q is typed during a protocol file transfer. : set calllog c:/calllog : set rxlog c:/tmp/rxlog : set txlog c:/tmp/txlog The above lines set the pathnames for logs of calls, files received, and files transmitted. set f10 "@help" if fyamhelp.t set helpfile "yamhelp.t" if f/umanh.hlp set helpfile "@yhp /umanh.hlp" if fumanh.hlp set helpfile "@yhp umanh.hlp" The above lines locate the help file and program F10 to summon the help processor if available. These lines may be changed if you keep these files in other directories. : if dc ps4 pn2 pr97 If a color display is used on DOS, uncommenting this line selects red status line (ps4), green normal text (pn2), and a blue/yellow for reverse video (pr97). These colors may be more suitable than the default black and white. Another possibility is "pn3" which selects blue-green for normal text. You may wish to experiment with these values to find ones best suited for your particular combination of display equipment and visual preferences. Changing the colors from time to time may prolong display tube life. The colors Telephone Directory entry* displays the colors generated by the possible numeric parameter values: EXAMPLE: gosub colors Some programs, including the "DEC Store" demonstration, will not display exactly as intended with some combinations of the above display parameters. You may wish to keep your phone numbers etc. in one file and relegate information specific to each computer to a separate file. The setup entry in phones.t checks for the existience of a phones.ts file and executes it of found. (C) 1989 Omen Tech Inc Chapter 8 Your Telephone Directory Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 36 set s0 "" setc pho "%PHONES\&s"; if f%pho source %pho if %s0 return The supplied phones.ts file is used on Omen's 386 Xenix system, and may be used as an example. On DOS, if you use VT100 emulation with keyboard mapping most of the time, you can add the contents of the keyboard mapping file std.mk, xen.mk, or 101.mk to your phones.ts file. While editing your telephone directory, you might wish to add some entries for your favorite systems in the same format used by the "amrad", "amsat", or "denver" directory entries. When the PHODIR.t file is ready, type "ZCOMM<ENTER>" to run ZCOMM. ZCOMM will print several lines of greeting and then silently execute the commands in the setup directory entry. If ZCOMM can't open PHODIR.t, exit ZCOMM with "x<ENTER>" and copy PHODIR.t to the correct directory, or set the DOS PHONES environment variable to the actual pathname (see Chapter 14). Also check that the DOS CONFIG.SYS files contains FILES=20 to allow ZCOMM a sufficient number of open files for proper script operation. If using DOS 3.2 or later, you will need to have a STACKS line in your CONFIG.SYS file, as described in Chapter 26. (C) 1989 Omen Tech Inc Chapter 8 Tutorial Introduction Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 37 9. HANDS ON TUTORIAL As a first order of business, run the demonstration program by typing ZCOMMDEMO at the DOS prompt. The demo asks certain questions about your system, and then allows you to exercise a few of ZCOMM's features from a menu. It's a good way to get a first "feel" for ZCOMM before getting down to business with the industrial strength software you will be using. Remember to turn off the CAPS LOCK key when running ZCOMM. ASSUMPTIONS: In addition to the minimum hardware requirements for ZCOMM, this tutorial assumes the use of a Hayes Smartmodem 1200 (or equivalent) connected to the COM1 port in accordance with the instructions in Chapter 7. The tutorial assumes that ZCOMM.EXE, YHP.EXE, UMANH.HLP, and PHODIR.t are copied to the root directory of your working disk, and that ZCOMM.EXE has been serialized with the putsnp program. If your system configuration is different, you will have to read the manual carefully to learn how to adjust for your configuration. After typing ZCOMM from the DOS prompt to load ZCOMM, type F10 to activate the flash-up help processor. Browse through it to familiarize yourself with the information available via the F10 (help) key. To make a call without using a directory entry, type speed 1200 (or whatever) and then the phone number: speed 1200 123-4567 The modem then dials the number. When you are connected, ZCOMM will return to its command prompt. Keyboard F2 to begin talking with the remote. Give some commands to the remote until several screens' worth of text have scrolled by. Now press the PgUp function key. The screen will now display text that had scrolled off before. Use the PgUp, Home, PgDn, and End function keys to move around in the review buffer. Look for a moderately interesting nugget of wisdom, and use the up arrow and down arrow function keys on the numeric keypad to place the interesting part at the top of the screen. Hit "t" to set the top marker. This causes all the text to display in high intensity. Now move down using the down arrow key to place the first line of unwanted text at the top of the screen. Hit the "b" key to set the bottom pointer. This will change the displayed text back to normal intensity. (C) 1989 Omen Tech Inc Chapter 9 Tutorial Introduction Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 38 Now hit "w" and ZCOMM will prompt for a filename to write to. Type the filename followed by <ENTER>, and ZCOMM will write the selected data. When the write operation is finished, the screen will redisplay the text. When you have the feel of it, type F1 to return to the term function and conversational connection to the remote computer. The demonstration disk circular buffer search/cut/paste menu choice demonstrates many of the review subcommands. Next, log off the remote computer. When it drops the line, ZCOMM displays No Carrier Detect in reverse video to announce that the connection has been lost. At this time you are still in the term function. Hit F1 to return to ZCOMM's command prompt. Then type "off<ENTER>" to disconnect the modem and exit back to the operating system. Now is a good time to read the rest of the manual to discover the power of ZCOMM. Chapter 9 presents some unusual sessions demonstrating more of ZCOMM's capabilities. 9.1 Sample Sessions Direct connection to COM2 at 19kb unix port 2 speed 19200 source 101.mk; t | | | | | | | Map keyboard, Invoke term function | | ___ Set 19200 bits per second | ______________ Select port COM2 _________________________ System name Typical bulletin board rcpm port 1 speed 1200 123-4567 t -8g | | | | | | | | | _ Term function, graphics | | | _______ Number to call | | __________________ 1200 baud | _________________________ Select COM1 ____________________________________ System name A Not so Typical Session The example below assumes a Hayes modem connected to a radio receiver tuned to the W1AW ASCII bulletins. Refer to a recent issue of QST Magazine for a W1AW schedule. to select the best signal. Usually, the error rate is lowest when receiving a strong signal near the Maximum Useable Frequency (MUF). Set the radio for Upper Sideband (C) 1989 Omen Tech Inc Chapter 9 Sample Sessions Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 39 (USB) reception. Tune it so the resulting audio frequencies make the RD (Received Data) light turn on about 50 percent of the time. Reset the modem by powering it down before attempting regular calls. w1aw speed 110 putw "ATS10=255 C0 H2 D\r" t -v | | | | | -v prints control chars | | as ^C so they won't | | erase the screen, etc. | Ignore Carrier Detect, Carrier Off, Special Off | Hook (Don't close relay), Originate, Online |________ W1AW ASCII transmissions are at 110 bps A>ZCOMM call unix Connect to a local system named unix jabber jabber ... Login to system, change directory <ALT-2>Command: Get a ZCOMM command prompt sz prg?.? prghlp.mm Upload some files jabber jabber ... sz *.c *.h Download some source files Receiving ... ZMODEM AutoDownload accepts them kermit -ix Start the Unix Kermit server <F1>>>>c: Get ZCOMM's command prompt remote dir Get a directory listing Directory... Directory listing on screen get f2 Get (fetch) a file f2 Open ... File arrives send myfile Send myfile to server finish Finish server access t Enter term function kermit send f1 Start a Kermit file transfer f1 Open... File is received AUTOMAGICALLY! jabber jabber ... Log off local system <F1>>>>c: Get ZCOMM's command prompt port 1 Select modem on COM1 call rcpm Dial a system called "rcpm" jabber jabber ... Keyboarding with remote <Home> Review function at top of text /to superhacker Search for beginning of message to you t Set top pointer /to j. fred muggs Search for beginning of next message b Set bottom pointer w Write selected text to a disk file <F1> Return to term function E<ENTER> Tell the rcpm to enter a message <ALT-2>Command: Get a ZCOMM command prompt open -pt letter Open "letter" and send to bbs, using prompt and throttle modes to slow transmission so the remote system won't drop characters. dir Find out what files are on the RCPM xmodem s foo.bqr Command RCPM to download a file (C) 1989 Omen Tech Inc Chapter 9 Sample Sessions Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 40 <ALT-2>Command: Get a ZCOMM command prompt rc foo.bqr Download a file with XMODEM/CRC PgUp PgUp ... Flip back to the first part of directory previously listed <ENTER> Back to term function xmodem s dr.who Download a critical file <ALT-2>Command: Get a ZCOMM command prompt rc \misc\dr.who Download the file jabber jabber ... More keyboarding, logoff <F1>>>>c: Get ZCOMM's command prompt Connect the modem to the radio's audio and tune in W1AW create rtty.tmp Create a disk file for the bulletins call w1aw bleep twort sneep Static on the radio - pure line hits until W1AW is received while sending ASCII <F2>k Review/k command clears the buffer QST DE W1AW ... END ... AR <ALT-C> Close the capture file <F1>>>>c:off Return to DOS (C) 1989 Omen Tech Inc Chapter 9 Accessing Computer Systems Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 41 10. ACCESSING COMPUTER SYSTEMS 10.1 Dialing Once you modem is interfaced per Chapter 7, you can connect to a remote system with the call command referencing an entry in your telephone directory. EXAMPLE: call kgbvax If a telephone directory entry has not been set up, TurboLearn(TM) may be invoked to dial a phone number and then learn your login procedure by keyboarding the F4 key. You may choose to add the resulting script to your telephone directory, or retain it as a separate file acessible with the source command. Please refer to the learn command in Chapter 15. If you just want to call a number without ZCOMM learning anything, just type the telephone number from the command prompt already.[1] EXAMPLE: 123-4567 When the modem connects, ZCOMM returns to the command prompt. You can then keyboard the F2 key to connect your keyboard to the remote system. If you wish to use "bulletin board graphics", use t -8g instead. 10.2 Telenet/PC-Pursuit For best results, identify with D1 when Telenet asks for your terminal type. This selection prevents the network from adding padding characters, which are just a waste of time with ZCOMM. To use XMODEM, YMODEM, Telink, and other traditional protocols on PC Pursuit, type SET 1:0,4:2,5:0,7:8,12:0 after connecting to the PC-Pursuit target city. This command prevents Telenet from "eating" control characters or breaking the connection when files containing certain patterns are transmitted. This command disables Telenet's "<ENTER>@<ENTER>" escape. For ZMODEM or Sliding Windows Kermit a better alternatitive is: __________ 1. You may wish to add the /mnp modifier described in Chapter 7. (C) 1989 Omen Tech Inc Chapter 10 Accessing Computer Systems Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 42 SET 4:2,5:1,12:1 Please refer to Chapter 13 for network flow control considerations. 10.3 Tymnet If using Tymnet, type Ctrl-R Ctrl-X just before the host computer name to enable software flow control with XOFF and XON characters. "Half Duplex" may be activated with Ctrl-H. Check with your network's documentation for further details or updates to this information. (C) 1989 Omen Tech Inc Chapter 10 File Names Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 43 11. FILE NAMES Good and Bad The pathnames of downloaded files must be legal PC-DOS file names as described in The File Specification in chapter 2 of the PC-DOS manual. When choosing file names, remember that PC-DOS does not distinguish between uppercase and lowercase characters in pathnames. The Compuserve-B, ZMODEM, YMODEM, and Kermit protocols use pathnames generated by the sending program. File names transmitted from other systems may not be legal for DOS, or they may reference directories that cannot be created.[1] When ZCOMM receives a pathname from the sending program, ZCOMM first checks for the existence of a file with the same name. If no such file is found, ZCOMM attempts to open the named file for writing. If the file cannot be created because directories specified in the pathname do not exist, ZCOMM attempts to create the directories. A pathname that cannot be opened for reading or writing is considered illegal. EXAMPLE: foo..bar is illegal for DOS because it contains two dots. An Illegal pathname is translated to name.NNN where name is the filename portion of the given file name restricted to 8 characters, and NNN is an assigned three digit number starting with 001 and incremented after each file download. If a file with this new name already exists, the number is incremented up to 999, until a unique file name is found. The open fails if a unique number cannot be found. EXAMPLE: A downloaded file with the name newprog.patch.1 might actually be downloaded as newprog.001. This check for illegal file names is made whenever ZCOMM attempts to create an output file. EXAMPLE: t foo.bar.baz given from the command prompt would invoke file name translation. __________ 1. A cirectory cannot be created if a regular file with the same pathname is present. (C) 1989 Omen Tech Inc Chapter 11 File Names Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 44 11.1 Pathname Translations Files affected by the dirrx and dircx string variables have their directory paths and/or device specifier stripped if the string variable ends in a "/". Otherwise a file specification with an absolute path overrides the string variable. The pathname of the incoming file is checked before any of these transformations, allowing a host system to place all files received with a protocol in a private directory. EXAMPLE: C>set DIRRX=C:/download places files received with a protocol in the download directory on drive C unless the file specification included an absolute path or device letter. dirrx File Stored Location (empty) any (same) C:/a f C:/a/f C:/a /f /f C:/a A:f A:f C:/a/ f C:/a/f C:/a/ /f C:/a/f C:/a/ A:f C:/a/f Parameter Affected commands dirrx r{bcotwx7}, fget, get, bdump, usq, ZMODEM/Kermit AutoDownload dirsx s{bctx7}, send, B protocol sends[2] dircx create, t, message, private, >, bro/a review/w, ap[d] (2nd argument) dirfx f, open To show the possible pathname translations, consider the pathmame: A:/spy/kgb/sabotage/666 sent between two copies of ZCOMM with the ZMODEM protocol. The sending program command: sz A:/spy/kgb/sabotage/666 sends the file name 666. The command sz -f A:/spy/kgb/sabotage/666 sends the complete pathname /spy/kgb/sabotage/666. The command sz ONAME=hogwash A:/spy/kgb/sabotage/666 sends the __________ 2. If the dirsx parameter is set, ambiguous or wild card file names cannot be used. (C) 1989 Omen Tech Inc Chapter 11 File Names Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 45 pathname hogwash. sz PREFIX=C:/fbi/security/intelligence A:/spy/kgb/sabotage/666 sends the pathname C:/fbi/security/intelligence/666. Note that a disk identifier (C:) is being sent. On reception with ZMODEM AutoDownload or the rz command, the last example (C:/fbi/security/intelligence/666) would normally be stored under that exact pathname, creating the directories C:/fbi, C:/fbi/security, and C:/fbi/security/intelligence if needed. If the dirrx string variable had contained C:/downloads the incoming drive specifier would still have overidden the dirrx specification. If the dirrx string variable had contained C:/ollie/to_do/ the file would have ended up as C:/ollie/to_do/666 to the consternation of all. The command rz foobar could have been used to rename this file to foobar in the current directory. The oncloserx and onclosetx string parameters may be used to specify commands to execute after each file received or sent with file transfer protocols. Their use is described in Chapter 11. (C) 1989 Omen Tech Inc Chapter 11 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 46 12. PROTOCOL FILE TRANSFERS With many different ways to transfer files with ZCOMM, your choice of file transfer methods could make the difference between efficient, error free data and slow or error prone transfers. This chapter gives an overview of the different ways to transfer files with emphasis on their relative merits. A file transfer protocol should have high integrity (assurance of accurate data) and high robustness (low probability of aborting a transfer). The following subchapters discuss these file transfer methods in more detail. 12.1 ZMODEM-90 ZMODEM was developed for the public domain under contract by Telenet, a major packet switched network. ZMODEM has been submitted to the ANSI X12C committee. ZMODEM-90(TM) is a refinement of ZMODEM with increased performance, reliability and compatibility with a wider variety of environments. ZMODEM provides a greatly simplified user interface. The file name is entered once, and transfer options may be given to the sending program, even those that apply to the receiver. ZMODEM AutoDownload(TM) allows menu and mouse driven programs to download files and commands with no extra keyboarding required. ZMODEM transfers one or more files with a single command. The size and transfer time for each file is displayed, and the total number of files, size, and transmission time is displayed when more than one file remains to be sent on a command. Keyboarding ALT-F allows the receiver to bypass an individual file without having to restart the batch. ZMODEM transfers both files and commands. Command download allows one of the computers to take positive control of the session. A security challenge (activated by ZMODEM AutoDownload(TM)) guards against Trojan Horse messages.* ZMODEM file transfers preserve the file date and the exact file contents, unlike traditional protocols that append garbage to files. Streaming transmission provides full throughput over satellite links and packet switched networks. One of three ZMODEM streaming control methods may be used with systems that allow the sender to monitor the received data for error correction packets without interrupting transmission. ZMODEM's "block length" is the entire file! (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 47 Individually acknowledged packets support other systems. ZMODEM allows programs to adjust the protocol parameters for optimum efficiency as the file is being sent. ZMODEM-90 allows programs to adjust character encoding for best results with a variety of systems. Some programs support ZMODEM compression for even faster file transfers under appropriate conditions with the Z file transfer option (q.v.). ZMODEM is immune to conditions that prevent reliable, accurate file transfers with traditional protocols: + ZMODEM data transfers are protected by the Federal Standard 32 bit CRC to assure reliable transfers. This 32 bit CRC gives an undetected error rate five orders of magnitude better than XMODEM's 16 bit CRC, and more than a billion times better than checksum XMODEM. ZMODEM uses 16 bit CRC for file transfers with programs that do not support 32 bit CRC. + Most important, all ZMODEM protocol transactions are protected by CRC. Other protocols advertising 16 or 32 bit CRC sometimes fail under stress because critical control messages are not protected by CRC. Omen Technology Inc's Intelligent Crash Recovery(TM) and advanced file management. If you've ever been disconnected when a huge file transfer was almost finished, you'll appreciate resuming/recovering the file transfer with the ZMODEM r option. You can use the ZMODEM n option to transfer only those files that have changed since the last time they were transferred. With the p option, you can unconditionally protect files that already exist on the destination system. To update only the files you already have while skipping the rest, use the Yn options. To send a file with ZMODEM, the command sz file1 can be given from either the main command prompt, or from the term function via a secondary command prompt obtained with ALT-2. Multiple files and wild cards may be used. EXAMPLE: sz file1 file2 *.lst 12.1.1 ZMODEM AutoDownload If Z mode has been enabled (the default), ZCOMM's term function will detect a ZMODEM transmission and receive the file(s) automatically, after a security check. File transfer options for ZMODEM automatic downloads may be specified with the adlopts string parameter. The rz command may be also given from a command prompt. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 48 Please refer to the sz and zcommand commands described in Chapter 15 for examples and information. Rz and sz programs for Unix and VAX/VMS are available in rzsz.zoo. 12.1.2 Tuning ZMODEM Parameters Chapter 21.2 describes a number of ZMODEM numeric parameters which may be adjusted for extraordinary situations, or to fine tune the last 0.1 per cent of possible performance. The ZMODEM subpacket length (zmodem L parameter) and the ZMODEM frame length (zmodem l parameter) deserve special mention. People tend to confuse these with the familiar 128 and 1024 byte block length used in XMODEM transfers. When a ZMODEM frame length of 0 is specified (the default), a single frame will span the entire file if there are no errors. This is the main source of ZMODEM's reputation for fast transfers. Setting the ZMODEM frame length to a number between 64 and 16384 restricts the frame length to that value. At the end of each frame, the sender stops sending and waits for an acknowledgement from the receiver. When set, the ZMODEM frame length corresponds in function to the 128 or 1024 byte block length of XMODEM based protocols. Each ZMODEM frame consists of one or more subpackets of 32 to 1024 bytes. Since the subpackets within a frame are sent without pause, a short subpacket length does not exact the terrible throughput penalty associated with short XMODEM and Kermit blocks. In the absence of transmission errors, a 256 byte subpacket length has about two per cent more overhead than a 1024 byte subpacket length. However, the longer subpacket length does increase error recovery time. ZCOMM dynamically adjusts the ZMODEM subpacket length on the basis of transmission speed and observed error rate. If you know what the error rate on a particular call will be before starting a ZMODEM file transfer, setting the zmodem L numeric parameter will provide a small but noticeable improvement in performance, with 1024 best for clean lines and smaller numbers better for noisy lines. When sending files over noisy phone lines not involving networks, the speed of error recovery may be increased by decreasing the values of the ZMODEM t and p numeric parameters. Fascinating information about ZMODEM and other protocols is provided in ymodem.doc and zmodem.doc, part of yzmodem.zoo (yzmodem.arc). 12.1.3 Moby Turbo When transferring compressed files over circuits that pass all 256 8 bit codes, Moby Turbo(TM) may be used for optimum speed by using the m option. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 49 12.1.4 Almost 8 bit Environments The e and m options may be used in conjunction with the xmtxesc and zmrxesc string parameters may be used to specify one or more control characters which cannot be passed over the serial line. SEE ALSO: zmtxesc, zmrxesc string parameters for details 12.1.5 7 Bit Environments ZMODEM-90 automatically detects 7 bit environments and adjusts accordingly. When transferring files with a large number of bytes with the 8th bit set, the P ("pack") option may be used to optimize 7 bit encoding. 12.1.6 Manual ABORT If a ZMODEM transfer fails abruptly under exceptional conditions the program on the remote machine may be manually terminated by repeatedly typing Ctrl-X characters at it until the program exits. 12.2 XMODEM Family Protocols 12.2.1 TRUE YMODEM(TM) Developed in 1981, YMODEM is finding its way into many communications programs. With Omen's Enhanced Data Recovery(TM), YMODEM gives excellent efficiency, integrity, and good robustness in many applications. True YMODEM transfers one or more files in a batch, without alteration or added garbage characters. True YMODEM also preserves the file date across multiple time zones. ZCOMM and the Unix(TM) rb and sb programs preserve the file modification date.[1] 12.2.2 YMODEM-1k The sb k option (1024 byte blocks) may be used to enhance throughput, especially when using timesharing systems, satellite links, or packet networks that can support the longer blocks. EXAMPLE: sb -k *.c *.h sends all .c and .h files in the current directory with 1024 byte blocks.[2] YMODEM and YMODEM-1k transfers can be received with the rb or F3 commands. __________ 1. Controlled by the d and z numeric parameters 2. ZCOMM switches to 128 byte blocks at the end of a file when the length warrants. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 50 YMODEM file transfers with Unix and VMS systems are discussed later in this chapter. A few obsolete programs claiming to support YMODEM actually use XMODEM with 1024 byte blocks; use ZCOMM's sx -k and rc commands when necessary to exchange data with these non standardized products. 12.2.3 YMODEM with OverThruster YMODEM and YMODEM-1k file downloading from networks and timesharing systems is slowed by response times. This slowing may be significant even when 1k blocks are used. With some systems, one can speed up YMODEM downloads by using the o option with the rb command to receive the file. Because OverThruster(TM) defeats error recovery, a line hit will usually abort a download. OverThruster(TM) may be used with X.PC or MNP error correcting link level protocols. EXAMPLE: rb -o SEE ALSO: O numeric parameter 12.2.4 XMODEM-1k The XMODEM-1k protocol transfers one file per command with 1024 byte blocks and a nominal 16 bit CRC. The file name must be entered for both the sender and the receiver. Programs lacking ZCOMM's Cybernetic Data Recovery(TM) logic are less likely to transfer data accurately under marginal conditions. XMODEM's use of every possible 8 bit code limit its effectiveness in many applications. The end of the file may be padded by up to 127 or 1023[3] garbage characters. To send a file with XMODEM-1k: sx -k file1 To receive a file with XMODEM-1k: rc file1 12.2.5 XMODEM-CRC (with fallback) The XMODEM-CRC protocol transfers one file per command. The XMODEM-CRC protocol requires the receiving program to initiate an XMODEM-CRC transfer. The file name must be entered for both the sender and the receiver. Even with CRC-16, programs lacking ZCOMM's Cybernetic Data Recovery(TM) are less likely to transfer data under marginal conditions. XMODEM-CRC's short data blocks and use of every possible 8 bit code limit its effectiveness in many applications. __________ 3. Some programs (including ZCOMM) limit this padding to 127 bytes. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 51 The end of the file may be padded by up to 127 garbage characters. To send a file with XMODEM (or XMODEM-CRC): sx file1 To receive a file with XMODEM-CRC: rc file1 12.2.6 Classic XMODEM The original MODEM protocol, developed by Ward Christensen, is supported by a large and growing number of programs operating on a variety of micros and minis. The base level XMODEM protocol gives good results when used over low error rate direct telephone connections. XMODEM's short data blocks and use of every possible 8 bit code preclude its application in many environments. File transfers with this protocol add up to 127 garbage characters to transferred files. The XMODEM protocol can transfer one file per command. The file name must be entered at both the sender and the receiver. To send a file with XMODEM: sx file1 To receive a file with Classic XMODEM: rx file1 12.2.7 Relaxed XMODEM ZCOMM's XMODEM and YMODEM support has been optimized for maximum reliability with a wide variety of systems under a wide variety of conditions. The default XMODEM and YMODEM timeout limits approach typical "relaxed" timings and rarely need to be lengthened except under the most sluggish of conditions. The zmodem t, T, and p numeric parameters (q.v.) control timeouts for XMODEM, YMODEM, and ZMODEM. The default values allow 10 seconds for a packet to appear and a maximum 5 second pause within a packet before starting error recovery. EXAMPLE: zmodem pt200 pp150 :: Set more relaxed X/Y/ZMODEM timing Omen Technology does not recommend tightening these timings for XMODEM and YMODEM transfers on noisy lines. 12.2.8 XMODEM with OverThruster XMODEM file downloading from networks and timesharing systems is slowed by short blocks and long response times. With some systems, one can speed up downloads by using the ro command to receive the file. Because OverThruster(TM) defeats error recovery, a line hit will usually abort a download. With nearly error free connections, one can save enough time from the increased throughput to make up for the failed transfers. OverThruster(TM) may be used with X.PC or MNP error correcting link level protocols. EXAMPLE: ro file1 (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 52 EXAMPLE: rb -o SEE ALSO: O numeric parameter 12.2.9 YMODEM-g: Traditional Overdrive The proliferation of error correcting modems has sparked a proliferation of YMODEM-g programs, more and more of which actually meet minimal YMODEM protocol specifications. YMODEM-g transmits 0 or more files per batch with an ACK-less variant of YMODEM-1k. The sender does not wait for individual data blocks to be acknowledged, allowing high speed transfers with error correcting modems. YMODEM-g assumes an error free communications channel. A single transmission error or character lost because of DOS or TSR interrupt latency ruins the entire transfer, and YMODEM-g does not support Crash Recovery(TM). ZCOMM supports True YMODEM-g with the sb and rb -g commands. EXAMPLE: sb *.old Sends files in the current directory with YMODEM or YMODEM-g protocol. The receiver controls whether YMODEM or YMODEM-g is used for the transfer. EXAMPLE: rb -g Receives with YMODEM-g protocol. 12.2.10 XMODEM Mutants Misrepresented as YMODEM Despite continuing education efforts, a few lazy software providers insist on identifying their mutant XMODEM protocols as "ymodem". They choose to ignore the definition of YMODEM that Ward Christensen wrote when he coined the term YMODEM in his April 1985 message: (a) a record 0 containing filename date time and size (b) a 1K block size option (c) CRC-16. In case of questions, please refer to ymodem.doc, part of yzmodem.zoo (yzmodem.arc) for for the official YMODEM protocol. 12.2.11 Qmodem-G/Streaming XMODEM The Qmodem program and certain bulletin boards provide an ACKless XMODEM mutant protocol selected with the Qmodem G protocol menu choice. The sx and rx -g commands support this mutant XMODEM. EXAMPLE: rx -g qmodem.fil (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 53 12.2.12 WXMODEM (People-Link) ZCOMM supports WXMODEM protocol downloads with the rw command. On the People-Link timesharing service, WXMODEM downloads are faster than XMODEM downloads. Throughput, reliability, accuracy, and amenities are not as good as ZMODEM or SuperKermit, but neither of these protocols are currently available on that system. WXMODEM adds up to 127 garbage bytes to transferred files. Omen Technology does not recommend WXMODEM for use over noisy phone lines. EXAMPLE: rw file1 12.2.13 MODEM7 Batch The MODEM7 batch protocol passes CP/M file names from the sending program to the receiver one character at a time. The compatibility, throughput, and reliability problems of this kluge prompted the development of YMODEM. Nonetheless, when it becomes necessary to transfer files with a program lacking more advanced protocols, MODEM7 batch is better than nothing. File names transmitted with the MODEM7 batch protocol must obey the restrictions of both 8 bit CP/M and DOS. The f option cannot be used with MODEM7 batch. Data transfer within MODEM7 batch uses XMODEM protocol, and all of XMODEM's weaknesses discussed above apply to MODEM7 batch. MODEM7 batch does not preserve the modification date or exact file contents. EXAMPLE: s7 file1.ext *.baz sends files with MODEM7 batch. EXAMPLE: r7 receives one or more files with MODEM7 batch. 12.2.14 Telink/FIDO The Telink protocol expands upon the MODEM7 batch kluge with a specially formatted block containing the length of the file and the local DOS time and date. All of the MODEM7 batch compatibility and reliability problems apply to Telink.[4] The zmodem Z numeric parameter or the z file transfer option may be used to correct the time/date stamping of files transferred between different time zones. EXAMPLE: zmodem pZ120; st file1.ext *.baz Sends the specified files with a 2 hour time zone adjustment. __________ 4. ZCOMM's rt and st commands were verified with Minitel 3.0 by Tom Jenning's Fido Software; other Programs may not produce the same results. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 54 EXAMPLE: rt -z60 Receives one or more files with a 60 minute time zone adjustment. 12.2.15 SEAlink When transferring files with the CLINK 1.13 compatible programs, ZCOMM's rb and sb commands recognize SEAlink's modified Telink protocol. The rb command allows a transmitting SEAlink program to use sliding windows. Telink time zone and file name considerations apply to SEAlink. In addition, because SEAlink uses all 256 of the possible 8 bit codes for both data transfer and protocol management, some modems and networks that operate with XMODEM will not accommodate SEAlink. As with the MODEM7 and Clink protocols mentioned above, the SEAlink protocol is included for convenience in situations where the YMODEM and ZMODEM protocols are not implemented.[5] EXAMPLE: zmodem pZ120; sb file1.ext *.baz Sends the specified files to a SEAlink program with a 2 hour time zone adjustment. EXAMPLE: rb -z60 Receives one or more files from a SEAlink program with a 60 minute time zone adjustment. 12.3 Kermit Kermit operates with a wide range of computer systems, including those whose restrictive terminal interfaces prevent XMODEM transfers. Kermit uses an encoding technique called quoting to represent control characters and (if necessary) parity bits with standard printable characters. It is one of the few asynchronous error correcting protocols that work properly with half duplex IBM front ends. Because of the overhead from character quoting, Kermit is less efficient (slower) than ZMODEM. Kermit can transfer one or more files per command, preserving the exact file length. The popular timesharing service The Source supports the Kermit file transfer protocol in ASCII and binary modes. Kermit was developed at Columbia University. The protocol and supporting mainframe programs are described in documents available from Columbia University and elsewhere. __________ 5. ZCOMM's SEAlink was verified with CLINK 1.13 by Systems Enhancement Associates. Other Programs may not produce the same results because of ambiguities in the SEAlink documentation and undocumented protocol variants. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 55 EXAMPLE: kermit sb file1 file2 EXAMPLE: kermit rb 12.3.1 Incompatible Kermit Dialects When sending files with the Kermit Protocol, ZCOMM uses all 8 bits for the transfer unless a 7 bit parity mode (e.g., ena -7e) is used, the kermit 7 numeric parameter is non zero, or the other program requests 8th bit qouting. If ZCOMM is using a 7 bit parity mode (such as ena -7m), ZCOMM requests 8th bit quoting unless the kermit 8 numeric parameter is non zero. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Both programs must use the same parity for Kermit file transfers to succeed. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Kermit does not provide an automatic means of forcing both the sender and receiver to use the same dialect. Files cannot be transferred if the two programs disagree on parity handling, Such failures are quite commonplace. A common symptom is a transfer that starts up normally but always fails at the same block. Setting appropriate parity corrects these Kermit failures. ZCOMM's Kermit AutoDownload(TM) (enabled with the K mode) allows the term function to sense the beginning of a Kermit file download, make the proper determination on whether to use 8 bit serial data, and execute the file download without user intervention. 12.3.2 Kermit Performance Enhancements Super-Kermit (Kermit with Sliding Windows) transmits multiple packets before waiting for a response, increasing throughput with timesharing systems and networks. ZCOMM uses sliding windows and CRC error detection if the other machine's Kermit supports them. ZCOMM also supports long packets for increased throughput with suitable systems, including many that do not support sliding windows. ZCOMM allows Kermit long packets up to 1000 characters on DOS, up to 2048 on 32 bit Unix systems. The maximum send packet length is set by the kermit l numeric parameter. ZCOMM will ask for sliding windows if this is set to 94 or less. EXAMPLE: k pl94 The maximum receive packet length is set by the kermit L numeric parameter. ZCOMM will ask for sliding windows if this is set to 94 or less. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 56 EXAMPLE: k pL94 With the default values for the kermit l and kermit L parameters, ZCOMM will choose long packets over sliding windows when a choice is possible. ZCOMM supports 12 bit Kermit checksums and 16 bit Kermit CRC for professional error detection performance. ZCOMM uses the most reliable Kermit error correction available. Shorter checksums may be forced by changing the kermit b numeric parameter. 12.3.3 ZCOMM Kermit Capabilities At a Glance Local operation..................Yes Remote operation.................Yes Transfers text files.............Yes Transfers binary files...........Yes Wildcard send....................Yes Filename collision avoidance.....Yes Can time out.....................Yes 8th-bit prefixing................Yes 8 bit serial data................Yes Sliding Windows..................Yes Long Packets.....................Yes Repeat count prefixing...........Yes Alternate block checks...........Yes Terminal emulation...............Multiple Communication settings...........Yes Transmit BREAK...................Yes IBM mainframe communication......Yes Transaction logging..............Yes Act as server....................no Talk to server...................Yes Advanced commands for servers....Yes Handle file attributes...........no Programmable reset string........Yes 12.3.4 Accessing Kermit Servers The commands to start up a Kermit server vary from system to system. Unix C-Kermit can be started in server mode with kermit -ix given to Unix or VMS. When the Kermit server is active, the ZCOMM get, send, and remote ... commands may be used. The ZCOMM finish command causes the remote Kermit server to exit to its operating system. 12.3.5 Kermit Caveats Some versions of Kermit translate files as they are sent, by default! Typical modifications include CR/LF to NL transformations and CPMEOF stripping. Before transferring binary files, such editing must be disabled with SET FILE TYPE BINARY or similar commands given to the other program. The demonstration in Chapter 9 includes several Kermit server access and file transfer commands. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 57 If the Kermit protocol doesn't work with IBM mainframe communications, incorrect ASCII/EBCDIC translate tables may be the problem. Some mainframe "front ends" require special characters or a break signal to recover from transmission errors ("line hits"). The kermreset string parameter (q.v.) may be programmed with the required sequence. SEE ALSO: kermreset string parameter When downloading files from some versions of Kermit, best results may sometimes be obtained by starting ZCOMM's kermit receive before typing the carriage return that starts the sender on the remote. If the other program includes an adjustable initial delay, you can save time by setting it to zero. SEE ALSO: kermit d numeric parameter SEE ALSO: K mode (Kermit AutoDownload(TM)) 12.4 Uploading Files to Remote Unix Systems Files may be uploaded to Unix systems conveniently and quickly with ZMODEM. Unix flavors of Professional-YAM support the full ZMODEM- 90(TM) feature set including Crash Recovery and selective transfers with the rz command, a hard link to the /usr/bin/yam program. The full featured Pro-YAM may not be available on a particular system. The rz program supports a subset of ZCOMM's ZMODEM features; see the rz program's manual page for more information.[6] The undos program __________ 6. If rz is not installed on the Unix system, unpack the rzsz.zoo file on your MSDOS system with: looz -e rzsz.zoo given from the DOS prompt. On Unix systems with Professional-YAM installed, the rzsz source files and man pages are located in /usr/src/command/rzsz. Next, the command source zupl.t calls the zupl.t script to upload the bootstrap file minirb.c, compile it, and use it to upload the remainder of the source files. After the rest of the files have been uploaded, compile rz.c and sz.c using the directions given in the README file and in the C source files. The manual "pages" rz.1 and sz.1 may be formatted with nroff commands such as nroff -Tlp -man rz.1 sz.1 (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 58 may be used to remove carriage returns from Unix files. When accessed over a network, some Unix systems may require additional control characters to be escaped. The sz command e option may be used to escape control characters. SEE ALSO: e option 12.5 Downloading Files from Remote Unix Systems To download files from Unix(TM) systems, use the Unix sz command to send the desired files to ZCOMM. To Unix keyboard: sz file ... ZCOMM's ZMODEM AutoDownload(TM) takes care of the rest for you, saving unnecessary keystrokes. If one or more of the files already exists on the destination disk, use sz -y file ... instead, to replace the old copies on your computer. Another useful option sends only the files that exist on both computers (Y), and furthermore sends only those that are newer (n): sz -Yn file ... When files are long and transmission slow, you can save time by squeezing them first with sq. Source for a Unix compatible version of sq is available in xsq.cq.[7] The zoo program, available for DOS and Unix, may also be used to compress file(s) before transmission. Omen Technology products support ZMODEM compression with the Z option. All Omen Technology products support compression by Run Length Encoding (RLE). Unix flavors of Professional-YAM also support LZW compression. Unix source files normally do not contain carriage returns used by CP/M and DOS. Some CP/M or DOS programs, such as C compilers, do not require carriage returns in the source files. Others, such as the Microsoft Macro Assembler, become quite confused by such files, although such files fully meet the requirements of the ASCII standard. Carriage Returns may be added before downloading with the todos or tocpm programs. Carriage returns may be added during the transfer with the sz a option. Carriage Returns may be added after the transfer by some program editors, including uEMACS. (Other editors, such as DOS edlin may crash trying to edit such files.) Short files (less than 64kb) may be converted using ZCOMM's read and create __________ 7. /usr/src/cmd/xsq.c on Unix systems. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 59 commands to pass the data through ZCOMM's capture buffer. Text files may also be downloaded using the capture buffer if sz has not been installed on the Unix machine. If a file or set of files are to be transported between two Unix systems, it may be helpful to place them in a tar or cpio archive (and possibly squeeze the archive) before transmission. This procedure will preserve the Unix file modes and modification times, and bypass pathname restrictions imposed by DOS. As with rz, Unix Professional-YAM is linked to sz to support the full ZMODEM-90(TM) feature set. Otherwise the separate Unix sz program may be obtained as described in the previous subchapter. 12.6 VMS File Transfers The abovementioned rz and sz sources also compile on the DEC VMS C compiler. Instructions for compiling, linking, and installing the programs are contained in the rz.c and sz.c source files. Most of the comments made above about Unix file transfers apply to VMS as well. The command source vupl.t calls the vupl.t script to upload the files needed to compile the programs on VMS. The script attempts to invoke a Kermit server and use Kermit to upload the files. If no Kermit server is found, the script uses the DCL create command to upload the files by emulating a paper tape reader. Make certain to "install" the VMS sz command to the DCL interpreter. 12.7 CompuServe File Transfers ZCOMM supports CompuServe Quick-B and the faster Extended Quick-B (B+) file transfer protocols. As this is being written, these protocols are being revised. Please check the newest.me file for possible changes. B+ Protocol is used by the CompuServe Timesharing Service through the CompuServe, Tymnet, and Telenet networks. B+ Protocol file transfers are initiated by the CompuServe computer. The B+ Protocol file transfer protocol is well supported by this timesharing service. Under typical conditions, the B+ Protocol saves 35 per cent or more in file transmission time and connect charges compared to XMODEM protocol transfers. The c or C mode must be set with ena -c or ena -C to allow the B+ protocol to seize control and transfer files. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers Version 17.50 TurboDial 2.33 Universal Line Printer Edition ZCOMM User Manual 60 The adlopts string parameter allows the y and v file transfer options to be specified for CIS-B transfers. The w numeric parameter controls the block length used by the CompuServe B+ Protocol. A longer length increases throughput, but may overload some networks, resulting in excessive retransmissions or failed transfers. With the new Extended Quick-B protocol, the maximum block length is 1024 data bytes. A value of 0 (the default) allows the Compuserve computer to control the block length, up to 1024 with Extended Quick-B. A negative value controls the upload block length but still allows Compuserve to control the download block length (1024 with Extended Quick B). Uploads to Compuserve using longer block lengths are especially sensitive to poor flow control, especially when error correcting modems (MNP, etc.) are used. If B protocol uploads fail or require excessive retransmissions, correct the flow control arrangements, disable the modem's error correction, or try a smaller upload block size. The data contents of successfully transferred file(s) are not affected by this parameter. Some networks may garble data when Quick-B's streaming causes ZCOMM to respond to incoming data concurrently with incoming data. The o numeric parameter can be set to 0 to disable streaming (send-ahead). It is essential to use the same interface speed to the modem as the modem's transmission rate when uploading files with B+ protocol. If the modem buffers any characters, ZCOMM's response to CompuServe's flow control will be too slow to prevent loss of data. The CompuServe B+ Protocol controls all file transfer operations (except permission to overwrite files) from the timesharing system. Waiting for long files to download can be boring. You can start the transfer and walk away from the computer, but CompuServe will stay connected for 15 minute$ after the transfer is finished if you don't come back when the download finishes. This expense can be avoided by typing ALT-Q once the protocol transfer has started. ALT-Q tells ZCOMM to disconnect as soon as the protocol transfer is completed, stopping the connect charges. An alternative method is to control the transfers with a script, using either ejryam or the less sophisticated cissig and dow.t scripts included with the software distribution. When "browsing" through CompuServe's software "downloading section" libraries, the kcisdl.t script file and ZCOMM allow you to download a file with a single keystroke: F3. Installation instructions are provided in that file. (C) 1989 Omen Tech Inc Chapter 12 Protocol File Transfers