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Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 31 stored in the modem's memory awaiting transmission. This is inefficient when a streaming file transfer protocol is used because the data stored in the buffer must be drained before error recovery can commence. The ZMODEM b and w numeric parameters should be used to manage the modem's data storage. + Autobaud to adjust the modem and computer speed. With this method, the modem is optioned to enter a search mode whenever it becomes idle. The dialing script calls the waketb phone directory subroutine to train the modem to the computer's transmission speed. The waketb subroutine may be optimized for the particular modem used. After dialing or answering a call, the modem handshakes with the remote modem and reports the connect speed with a message such as "CONNECT 1200" or "CONNECT FAST". The dialing script recognizes the string, and sets the computer to the correct speed. If the connection is made at high speed, the dialing script may need to enable hardware flow control with a handshake command. 8.9 PROBLEM MODEMS A few modem models, particularly low cost internal modems, are known to cause problems with ZCOMM. In some cases, playing tricks with the speed command and the G and P numeric parameters (q.v.) overcomes some design deficiencies in these modems. Some internal modems have been known to leak phone line spikes to the computer, provoking erratic operation. 8.10 Line Sharing with FAX Machines Sometimes you can share a dial-in line between a modem and FAX machine without extra hardware. Many modems have both line and phone jacks, and they disable the phone jack when the modem is online. Connect the modem to the line and connect the FAX machine to the modem's phone jack. Next, determine how many rings the FAX machine requires before answering the phone and set the modem to the same value with the modem's S0 register. Set the modem carrier detect time limit to 18 seconds with the modem's S7 register. When the phone rings, both the FAX machine and modem try to pick up the phone line, but the modem disconnects the FAX machine from the line while it attempts to handshake. If the incoming call is for the modem, the FAX machine will time out after about a minute. If the call is for the FAX machine, the modem will reconnect the FAX to the phone line after its 18 second timeout. Your results may vary depending on the type of modem and FAX machine (C) 1994 Omen Tech Inc Chapter 8 Unleashing the MODEM Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 32 you use. EXAMPLE: call init,aa initializes a MultiTech modem to answer on the second ring. 8.11 Bidirectional Modem Ports on Unix Systems Some Unix systems support bidirectional modem operation, e.g., dial-in and dial-out on the same modem line. Please consult the system specific installation notes for more information. 8.12 AT&T Paradyne Comsphere 3820 This modem does not enable V.42 without also enabling MNP and speed buffering. Accordingly, this is the default for this modem. To disable MNP, V.42, and speed buffering use the /dir dialing modifier. Set the MODEM environment variable to cs3820.t to support this modem's link level features. 8.13 AT&T DataPort / Keep In Touch The commands for these modems are very similar to the the Comsphere 3820. The KIT modem PCMCIA card includes enhancements for optimum operation over cellular radio calls. 8.14 Hayes Optima Modems Use ho288.t to support Hayes Optima modems including the 288 model. 8.15 Supra FAXModem V.32bis Set the MODEM environment variable to supra.t to support this modem's link level features. 8.16 TELEBIT TrailBlazer The Telebit TrailBlazer modem uses 68000 and TMS320 processors to transmit serial data at rates up to 14000 bps over standard phone lines. The modems also operate at speeds of 2400, 1200, 300 and slower. The TrailBlazer is one of the most complex modems to fully exploit, a worthy challenge for a TurboDialTm script. Set the MODEM environment variable to tb.t to support the TrailBlazer's MNP, speed and flow control features. Before making calls, use the init phone entry to initialize the modem's non volatile memory with proper settings for ZCOMM. EXAMPLE: call init (C) 1994 Omen Tech Inc Chapter 8 Unleashing the MODEM Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 33 Telebit modems feature protocol spoofing designed to increase the performance of traditional file transfer protocols such as XMODEM, Kermit and UUCP. Spoofing manipulates the data stream and bypasses error detection protocols. Telebit protocol spoofing interferes with other protocols, slowing or preventing file transfers. Some Telebit spoofing modes require primitive or nonstandard versions of the "supported" protocol. Telebit "ymodem" spoofing does not work with YMODEM. Telebit "kermit" spoofing does not work with modern Kermit programs. Do not use spoofing except for UUCP connections. The tb.t dialer script disables spoofing by default. ZMODEM provides optimum file transfer speeds with these modems. ZMODEM avoids interference with the modem's flow control. This posting is intended for those who use Pro-Yam for access to Xenix/Vpix with Wyse 60 terminal emulation mode. These modem register settings are in use on a Telebit T1000 calling a Telebit trailblazer modem. The host modem has register 58=3 (xon/xoff). While these may not be the optimal settings.. they work !!. E1 F1 M1 Q0 T V1 W0 X1 Y0 &P0 &T4 Version FA2.00 S00:010 S01=000 S02=043 S03=013 S04=010 S05=008 S06=002 S07:045 S08=002 S09=006 S10=007 S11=070 S12=050 S18=000 S25=005 S38:020 S41=000 S45:255 S47=004 S48:001 S49=000 S50=000 S51=255 S52:002 S54:003 S55=000 S56=017 S57=019 S58:002 S59=000 S60=000 S61=150 S62=003 S63=001 S64=000 S65=000 S66=000 S67=000 S68=255 S69=000 S90=000 S91=000 S92:001 S94=001 S95:002 S96=001 S100=000 S101=000 S104=000 S111=255 S112=001 S121=000 S130:000 S131:001 S255=001 Courtesy Dr. Adam Orden 8.17 MultiTech MultiModem V32 EB This modem adds V.32bis and V.42bis to the MMV32. The /c option enables modem compression. 8.18 MultiTech MultiModem V32 This modem adds 9600 bps V.32 to the MM224e. 8.19 MultiTech MultiModem 224E Set the MODEM environment variable to mm224e.t to support the MM224E's MNP, speed and flow control features. Set dip switch 1 on the bottom of the modem to up (DTR Normal), the reverse of the factory setting. For high speed operation, CTS flow control should be enabled with internal switches and jumpers. Before making calls, use the init phone entry[2] to initialize the (C) 1994 Omen Tech Inc Chapter 8 Unleashing the MODEM Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 34 modem's non volatile memory with proper settings for ZCOMM. EXAMPLE: call init This disables automatic error correction under mnp. If you wish to enable this setting by default, merely type, from the terminal mode, 'AT &E1 &W', and the 'OK' which will ensue tells you that the command was accepted and stored in non-volatile memory. The init script also disables MNP compression. MNP compression slows transfers of compressed files. If you do not transfer many compressed files, change the &E14 in the init script to &E15. 8.20 MultiTech MultiModem 224 Set the MODEM environment variable to mm224.t to support the MM224. 8.21 U.S. Robotics Courier 2400e Unlike most medium and high speed modems, the Courier 2400e does not recognize the computer's transmission speed when given "AT" commands. Set the MODEM environment variable to c2400e.t to support the C2400E. This modem should be initialized with the init entry in the telephone directory. Switch settings are off, off, on, off, on, off, off, on, on, off. 8.22 U S Robotics HST Dual Standard The init phone directory entry should be run to initialize the HST properly. The HST firmware design requires the MNP DTE speed set in the first script line of hst.t to match the speed used in initmodem If you wish to change the interface speed, the speed must be changed in both places. When making MNP calls to CompuServe and certain other modems, a /2400 modifier may be required with some HST firmware versions to correct a MNP4 compatibility problem. EXAMPLE: compuserve speed 2400 123-4567/mnp/2400 ______________________________________________________________________ 2. Information courtesy Earle Robinson (C) 1994 Omen Tech Inc Chapter 8 Unleashing the MODEM Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 35 8.23 Hayes Ultra Smartmodem 9600 Set the MODEM environment variable to hu96.t to support the modem's MNP and flow control features. This modem should be initialized with the init entry in the telephone directory. The V.42 link level error control is enabled by default because it does not appear to interfere with connections to modems not supporting V.42. 8.24 Hayes Smartmodem V9600 This modem should be initialized with the init entry in the telephone directory. The AFT link level is enabled by default because it does not appear to interfere with connections to modems not supporting AFT. 8.25 Hayes Smartmodem 2400 The Hayes Smartmodem 2400 presents the same considerations as the Smartmodem 1200 described below. Unlike the 1200, the 2400 uses a non volatile memory to store configuration parameters instead of the switches used in earlier models. The sequence AT&C1 &D2 &R1 &S1 &T5 &W should be sent to the modem to set normal operation for DCD, DTR, CTS, and DSR. The T5 command disables remote loopback request, a source of failed file transfers on noisy lines. Finally, the &W command writes this information to the non volatile memory. Please consult your Hayes manual for more information on these commands. 8.26 Hayes Smartmodem 1200 Set the MODEM environment variable to sm1200.t to support the Smartmodem 1200 and similar 1200 bps modems. Some modems may require a change in the X1 command to a higher Xn digit for proper autobaud operation. The Smartmodem 1200(TM) should be configured as follows by setting S1-S8, located under the front panel. These switches may be accessed by gently prying the ears of the front bezel, allowing the bezel to pop off the front of the unit. S1 Up Support DTR Lead S2 Up Verbal result codes (Verbose) [3] S3 Down Result codes are sent S4 Up Echoes characters in command state S5 Down Modem does not answer calls initially __________ 3. If other options are necessary (to support other software) a custom dial routine may be used as described in Chapter 99. (C) 1994 Omen Tech Inc Chapter 8 Unleashing the MODEM Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 36 S6 Up Carrier Detect line reads status S7 ???? See Hayes manual S8 Down Enables Smartmodem 1200 command recognition The modem cable should connect the following RS-232 circuits: AA BA BB AB CF CD which use pins 1,2,3,7,8, and 20 on the Hayes modem. Some programs require pins 5 and 6 connected to the modem. NOTE: Some Hayes modems require mprefix to be in upper case only. "Hayes Compatible" modems not manufactured by Hayes generally work with the same mprefix, but some of the other modem control strings that appear in the distributed PHODIR.t file may not work properly with a particular brand of modem. 8.27 Microcom AX9624c Microcom AX modems have a configuration switch to select Hayes style "AT" commands. The AX/9624c front dip switch should be set 1, 4, 6, 7 UP, 2, 3, 5, 8 DOWN, and A/S OUT (asynchronous). The rear switches are all UP. Of all these switches, it is vital that front switch 2 be DOWN (AT commands) and rear switch 6 be UP; the init script should override the others. Set the MODEM environment variable to ax9624.t to support the Microcom AX9624's MNP and flow control features. Before making calls, use the init phone entry to initialize the modem's non volatile memory with proper settings for ZCOMM. EXAMPLE: call init 8.28 Microcom SX Series Older Microcom SX series modems have a unique command set incompatible with Hayes modems. Careful attention must be paid to flow control issues to obtain reliable operation. When using XMODEM or other protocols, the modem must be set to pass all 8 bits and all 256 code combinations of those 8 bits. The dialsx script sets the modem to "transparent software flow control" as described in Chapter 14. Change the line set mcommand "gosub dial" to set mcommand "gosub dialsx" in the setup telephone directory entry. (C) 1994 Omen Tech Inc Chapter 8 Unleashing the MODEM Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 37 8.29 Prometheus ProModem 1200 The following switch setting works with ZCOMM: 1-4,6,9 on; 5,7,8,10 off.[4] A custom "dial" script can be written to operate this modem in its native mode. 8.30 Standard 103/212 The supplied "dial" script will present the number to the user and wait for a success/fail response if the mprefix string parameter is set empty. Alternatively, one could change the script to loop waiting for carrier detect while the keyboard is inactive. The Data Set Ready (DSR) signal may be connected to the modem's speed detect output (high for 1200 bps, low for 300) allowing the dr test condition to sample the DSR line to determine the speed of the incoming call. 8.31 Data Race BMX These modems have a switch selected interface speed, an AT style command set, and switch options for software or hardware flow control. Recommended settings are: AT commands, Dialup, 8 bit data (down), disable XON (7 and 8 down), Echo on. ZCOMM's handshake on command should be used. 8.32 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. __________ 4. Prometheus mode does not work with ZCOMM's built-in dialing software because the "DIAL COMPLETED" message makes ZCOMM think it's seen "CONNECT" (ZCOMM looks for a "T"). (C) 1994 Omen Tech Inc Chapter 8 Unleashing the MODEM Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 38 8.33 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. 8.34 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, device drivers, extended memory disks or caches, and DOS clock interrupts. 8.35 MobyBaud(TM) Direct Connect File Transfers Sometimes one needs to update the files between two machines sitting right next to one another on a table top. With no modems and no line noise to worry about, software and procedures that would only work in a magazine testing environment are perfectly adequate. With fast 32 bit CPUs and FIFO buffered serial port devices, speeds beyond the generally available 19200, 38400 and 115200 bps settings are possible. Imagine sending files at over 200 kilobaud with (almost) standard hardware! Standard serial ports used on IBM compatible PCs are driven by a 1.8432 MHz clock, supporting transmission speeds to 115200 bits per second. MobyBaud allows higher speeds by substituting a higher frequency clock signal or crystal up to 8 MHz. A 4 MHz crystal more than doubles the top speed. Please consult the National Semiconductir NS16550AFN spec sheet for simple crystal clock circuits. A NS16550AFN chip can be modified for MobyBaud operation by __________ 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) 1994 Omen Tech Inc Chapter 8 Unleashing the MODEM Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 39 lifting pins 16 and 17 and connecting them to the crystal circuit. The crystal circuit can use pin 20 (not lifted) for signal ground. This modified chip plugs into a 8250/16450/16550 socket for MobyBaud; plugging in an unmodified NS16550AFN restores normal operation. When the clock is increased, the portx command must be used to specify the nonstandard new clock speed. EXAMPLE: portx 3e8,15,57600 speed 200000 Selects a comm port with a base address of 3e8 using IRQ15 and the 18.432 MHz clock option on the Boffin Electronics "WinSport II" 2 port serial board. MobyBaud operation at the fastest possible speeds requires a few tricks not needed at traditional speeds. Even the 16 deep FIFO on 16550A devices is not always enough for 200000 bps and faster operation. One technique is to combine ZMODEM Segmented Streaming and a large disk buffer. This technique requires the following commands given to the receiving program before starting file transfers: EXAMPLE: pI16384 z pl16384 (C) 1994 Omen Tech Inc Chapter 8 Your Telephone Directory Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 40 9. 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 contains telephone numbers, login scripts, and telephone dialers. The telephone directory is a plain ASCII text file which can be edited with standard text editors (edit, elvis, brief, teco, EMACS, vi, etc.). 9.1 Taking a Shortcut with PHOMAST.T >>> Pro-YAM Function Key Menu <<< Alt-N EMERGENCY EXIT, 'Nuke It' to get out of trouble/escape a command F1 Exit Circular Buffer F2 Enter Circular Buffer F3 OPEN Capture file F4 Send ASCII Text F5 Send Kermit Upload F6 Send Zmodem Upload <<BEST>> F7 Receive CrcXmodem Download F8 Send CrcXmodem Upload F9 Press for THIS HELP SCREEN F10 Online Manual Alt-1 Get DOS Command prompt Alt-2 Get Pro-YAM Command prompt sF3 Holds you on-line... sF4 Use Turbolearn Script Writer sF6 Change YOUR defaults sF7 Dialing Menu example aF1 AutoLog B&F Tech BBS (2400B) aF2 AutoLog Olde Guard BBS (1200B) aF3 CLOSE Capture file aF4 CIS DEMO at 1200 baud aF5 Call PC Magazine's BBS aF6 Enter HOST MODE operation aF7 Sign name on-line... ALT-F9 Edit PHOMAST.T script TO CALL OTHER BBSs: enter 'call name' where name is a label >>To DIAL A NUMBER just enter number followed by ;t (e.g. 523-8994;t)<< -- CompuServe-B, KERMIT, and ZMODEM download automatic -- Stop Redialing ---- press <CR> Hangup w/o pgm exit - enter 'o' PgUp into Buffer; <CR> to return -> EXIT hit F1 then -- enter 'off' (F9=Menu) c:/usr/tmp-> (a = Alt key, s = Shift key) Phomast features fully automated menu configuration, autospeed detection, and lots of slick coding examples. When run for the first time phomast will generate a file called PROFILE.DAT containing configuration information. When you enter 'yam' or 'zcomm' at the DOS prompt, the script will ask you a few questions to set up the configuration to include COM port identification and modem initialization, and you are ready to communicate immediately thanks to the power of the script language built into ZCOMM. The PHOMAST.T starter script was written by Michael Ash of La Jolla, (C) 1994 Omen Tech Inc Chapter 9 Your Telephone Directory Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 41 California. It is easy to configure and use by following the detailed instructions included in PHOMAST.DOC. Under COLORS, you may select the alternate screen colors. These will be automatically set by the menu configuration and only need to be changed if you don't like the default colors... To see the possible colors and their associated code numbers, from the command line prompt enter: 'gosub color' and hit return. Under MODEM SETUP, if your modem doesn't respond correctly to the defaults, just select another modem setup string. A default modem string is already configured and will work in most cases if your modem accepts the Hayes command set. Phomast assumes the modem has not locked its interface speed. To use phomast.t with Pro-YAM, you must first set the DOS PHONES environment variable to the full pathname (including drive and directory) of your phomast.t file. EXAMPLE: set PHONES=c:/yam/phomast.t This command may be added to your AUTOEXEC.BAT file. Alternatively, you can change ZCOMM's default Telephone Directory with the putsnp program. 9.2 Customizing PHONES.T Phones.t is the "industrial strength" prototype directory. While not as easy to learn as phomast.t, it is powerful enough to fully exploit TrailBlazer and other complex modems. By default, 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/flash_gordon/bin/phones.t; export PHONES (for Unix) The putsnp program may also be used to change ZCOMM's default Telephone Directory pathname. 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) 1994 Omen Tech Inc Chapter 9 Your Telephone Directory Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 42 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 original setup entry which appears later in the file. setup set answerback "\r\nYOUR NAME CITY\r\n\21" The first line of the "setup" entry sets the anserback used by the term function. Change the answerback setting to reflect your name.[1] Be sure to keep the \21 at the end of the string.[2] 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 mprefix "ATDT" sets the string parameter mprefix to ATDT, allowing the modem to use tone (DTMF) dialing. If your phone line requires pulse dialing, comment that line out (place a leading colon to make ZCOMM pass over it) and uncomment the line containig "ATDP". 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. __________ 1. Some timesharing systems may require a specific answerback string. 2. See Chapter 26 for a description of character escapes. (C) 1994 Omen Tech Inc Chapter 9 Your Telephone Directory Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 43 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.[3] 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.) The next lines configure a number of soft keys starting with F3 and finishing with FS4. Their functions are described at the end of Chapter 19. if du goto unixs if dv goto vmss The above lines check for the Unix and VAX/VMS operating system and branch to commands suitable for these operating systems. The following line applies to DOS and OS/2 flavors only. pz480 : set PST timezone The number in the pz480 command should represent the local time zone expressed as minutes behind GMT.[4] : ps8 :set C/G status line attribute to dim : if dc pn3 ps4 pr97 :if RGB, cyan, red stat, blu/y rev video : if dc ps11 pn14 pr30 :y on bl, rev. blue on lt. bl. status One of these lines may be uncommented and fiddled with to set a comfortable color scheme. If a color display is used on DOS, uncommenting the second line selects red status line (ps4), cyan normal text (pn3), and a blue/yellow for reverse video (pr97). These colors may be more suitable than the default black and white. Another possibility is "pn2" which selects 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: __________ 3. Use the "setsavenet" entry in PHODIR.t as a prototype. 4. Pacific Standard Time is 480 minutes behind Greenwich Mean Time (C) 1994 Omen Tech Inc Chapter 9 Your Telephone Directory Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 44 EXAMPLE: gosub colors Some programs, including the "DEC Store" demonstration, depend on the default shades of black and white for their visual effects, and will not display as intended with some of these color combinations. : 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 calllog c:/tmp/calllog : set rxlog c:/tmp/rxlog : set txlog c:/tmp/txlog The above lines enable logging to disk. They set the pathnames for logs of calls, files received, and files transmitted. set lib c:/yam set tmp c:/tmp Some of the supplied scripts expect to find other script files in a particular directory. The lib variable specifies the directory used for these scripts. Some scripts are written to place data files in the directory specified by the tmp variable. set helpfile "@!yhp /yam/umanh.hlp main" set f10 "@help" goto setup2 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. Some users use Zcomm on different machines or different operating systems. You may wish to keep your phone numbers etc. in one file common to all machines, 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 if found. set s0 "" setc pho "%PHONES\&s"; if f%pho source %pho if %s0 return The supplied phones.ts file is used on some of Omen's Unix and DOS systems, 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. (C) 1994 Omen Tech Inc Chapter 9 Your Telephone Directory Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 45 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 16). 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 may need to add a STACKS line to your CONFIG.SYS file, as described in Chapter 34. EXAMPLE: STACKS=20,128 (C) 1994 Omen Tech Inc Chapter 9 Tutorial Introduction Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 46 10. HANDS ON TUTORIAL 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 8. 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. 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. (C) 1994 Omen Tech Inc Chapter 10 Tutorial Introduction Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 47 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 10 presents some unusual sessions demonstrating more of ZCOMM's capabilities. 10.1 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 (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. (C) 1994 Omen Tech Inc Chapter 10 Sample Sessions Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 48 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 options 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 <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 (C) 1994 Omen Tech Inc Chapter 10 Sample Sessions Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 49 <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) 1994 Omen Tech Inc Chapter 10 Accessing Computer Systems Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 50 11. ACCESSING COMPUTER SYSTEMS 11.1 Dialing Once you modem is interfaced per Chapter 8, 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 19. 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. 11.2 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 8. (C) 1994 Omen Tech Inc Chapter 11 Accessing Computer Systems Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 51 SET 4:2,5:1,12:1 Please refer to Chapter 14 for network flow control considerations. Example scripts that access Telenet are provided in the phones2.t file. 11.3 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. Example scripts that access Tymnet are provided in the phones2.t file. (C) 1994 Omen Tech Inc Chapter 11 File Names Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 52 12. 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) 1994 Omen Tech Inc Chapter 12 File Names Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 53 12.1 Pathname Translations Files affected by the dirrx, dircx and dirpx 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, ZMODEM/Kermit AutoDownload dirsx s{bctx7}, send, B protocol sends[2] dircx create, t, message, private, >, bro/a ap[d] (2nd argument) dirpx review/w 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) 1994 Omen Tech Inc Chapter 12 File Names Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 54 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 13. (C) 1994 Omen Tech Inc Chapter 12 Protocol File Transfers Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 55 13. PROTOCOL FILE TRANSFERS 13.1 Graphic File Transfer Display #---------------------------------------------------------------------# # Professional-YAM Copyright 1991 Omen Technology INC #** # #** # ZMODEM RECEIVE #** # #** # File pcmagc.dmp 1 of 5 #** # #** # Current 43520 of 43520 Total 43520 of 999879 #** # #** # This ################################################## #** # 0------------------------50------------------------100% #** # Total ##- #** # State START FILENAME COMPARE DATA CORRECTING FINISH WAIT #** # Throughput 8704 Retries 0 Time left 2 min #** # Connect ET 13:09 Time 13:18 Modem status #** # #** # #** # Packet LEN 43520 TRANSPORT COMPRESSED DATA BINARY #** # Subpkt LEN 512 Window SIZ #** # ALT-F Cancel File ALT-B Cancel Batch #** # #** #---------------------------------------------------------------------#** ************************************************************************ 38kbps batch file download from a Unix system.[1] ZMODEM-90(TM) compression yields 87kbps effective speed on the PC Magazine Compressible File benchmark.[2] GSZ, ZCOMM and gYAM feature a full screen graphics status display of file transfer statistics. The amount of information displayed depends on the protocol and sending program. XMODEM, CompuServe B+, and Kermit download displays use information supplied to the estimate command. In the absence of a user specified throughput value, Time left is calculated with real time data. Real time throughput may be __________ 1. Pto-YAM screen snapshot made with ALT-Z. The resultant YAMPIC file was renamed to YAMPIC.BIN and read in to THEDRAW. Thedraw output the screen contents in IBM ANSI format, which was then typed and screen dumped to Postsctipt with SCRtoPS(TM) by Olfe Enterprises. 2. Page 159, April 30 1991 PC Magazine. (C) 1994 Omen Tech Inc Chapter 13 Protocol File Transfers Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 56 inflated for the first 5-20 kilobytes when a streaming protocol sends data. On PCDOS YAM flavors, call (connect) elapsed time, time of day, and MODEM status are displayed. MODEM status is displayed as follows: x Software flow restraint (XOFF) X Hardware flow restraint (CTS, etc.) L Loss of Carrier Detect signal (CD) H On Hook (DTR off) The color scheme may be altered with the ZCOMM gcolors command (q.v.). The gcolors program generates a one line script file with a customized gcolors command. gcolors is menu driven and is mostly self explanatory. First gcolors asks for the file name to modify. You may answer with the name of a new file to receive the resulting gcolors command. If you specify a file name that has been previously written by gcolors, the old color setup is first read from that file. Do not specify any other type of file to gcolors. When you finish customizing colors, save your changes to disk. You can then add the file contents to your setup directory entry. Sight impaired users can disable the blinking selection pointer with the gcolors q option. EXAMPLE: gcolors -q The gcolors top menu provides three choices: Choose colors, Save changes, and Quit. Some Choose Colors menu choices are not shown on the display for lack of space: space increment foreground color Enter select the next field F decrement foreground color (f increments) B decrement background color (b increments) (C) 1994 Omen Tech Inc Chapter 13 Protocol File Transfers Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 57 13.2 Choosing the Best Protocol A file transfer protocol should have high integrity (assurance of accurate data) and high robustness (low probability of aborting a transfer). And, it should be as fast as possible without compromising reliability. When PC Magazine tested file transfer protocols in early 1991, they ignored the file transfer recommendations given in this manual. Their ignorance slowed Pro-YAM file transfers by as much as 400 per cent. With many different ways to transfer files, your choice of file transfer methods can make the difference between efficient, error free data and slow or error prone transfers. The following subchapters discuss file transfer methods in more detail. 13.3 ZMODEM-90(TM) ZMODEM was developed in 1986 for the public domain (PD) under contract by Telenet, a major packet switched network. Omen Technology's commitment to file transfer technology did not stop with PD ZMODEM. ZMODEM-90(TM) is Omen Technology's copyrighted refinement of PD ZMODEM. ZMODEM-90 speeds transfers with COMPRESSION and other accelerators. ZMODEM-90 adds frame types to support transfers in 7- bit environments. ZMODEM-90 sends files faster and more reliably than PD ZMODEM. Omen Technology's ZMODEM-90 transfers files accurately in many applications where other ZMODEM programs abort or corrupt data. 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 can preserve the file date and the exact file (C) 1994 Omen Tech Inc Chapter 13 Protocol File Transfers Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 58 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! 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. ZMODEM is resistant 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 CRC protected. If you've ever been disconnected when a huge file transfer was almost finished, you'll appreciate resuming/recovering the file transfer with ZMODEM Crash Recovery Omen Technology Inc's Intelligent Crash Recovery(TM) guards against file corruption during Crash Recovery operations. (ZMODEM r and rr options.) 13.4 Sending files with ZMODEM 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 Please refer to the sz and zcommand commands in Chapter 19 for more examples and information. 13.4.1 File Maintenance with ZMODEM Omen Technology ZMODEM gives you the tools to maintain up to date files on multiple machines. You can use the ZMODEM n option to transfer only those files that have changed (C) 1994 Omen Tech Inc Chapter 13 Protocol File Transfers Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 59 since the last time they were transferred. With the p option, you can unconditionally protect files that exist on the destination system. To update only the files you already have while skipping the rest, use the Yn options. You can update an entire directory tree with the R option. EXAMPLE: sz -n -f -R chart sends the chart directory and all its subdirectories. The -n option skips old files. The -f option causes the pathname to be sent; otherwise all files would appear in the same directory on the receiving system. SEE ALSO: File Transfer Options, Chapter 20. 13.4.2 MobyTurbo Accelerator Standard ZMODEM escapes network control characters. This causes a slight drop in throughput when sending compressed files. When transferring compressed files over circuits that pass all 256 8 bit codes, MobyTurbo(TM) may be used to optimize speed. MobyTurbo provides the raw transfer speed of YMODEM-g and other fragile protocols without sacrificing ZMODEM's safety or robustness. MobyTurbo is activated with the m option. The m option may be used with the sz or rz command. EXAMPLE: sz -m *.zip MobyTurbo may be used with ZMODEM AutoDownloads by adding the m option to the adlopts string. EXAMPLE: set adlopts m .Sa m file transfer option 13.4.3 ZMODEM Compression ZMODEM-90 programs support ZMODEM compression for fast transfers of compressible files with the Z file transfer option. The amount of compression (and speed increase) depends on the structure of data in the files. EXAMPLE: sz -Z pcmagc.dmp SEE ALSO: Z file transfer option (C) 1994 Omen Tech Inc Chapter 13 Protocol File Transfers Version 18.18 TurboDial 2.41 Universal Line Printer Edition ZCOMM User Manual 60 13.5 Receiving files with ZMODEM 13.5.1 ZMODEM AutoDownload If the Z term option has been enabled (the default), ZCOMM's term function will detect a ZMODEM transmission, perform a security check, and receive the file(s) automatically. File transfer options for ZMODEM automatic downloads may be specified with the adlopts string parameter. EXAMPLE: set adlopts m Requests MobyTurbo(TM) accelerator for downloads. 13.5.2 Manual ZMODEM Downloads The rz command may be also given from a command prompt. SEE ALSO: rz command 13.6 Tuning ZMODEM Parameters Chapter 24.2 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 (C) 1994 Omen Tech Inc Chapter 13 Protocol File Transfers