Columbia Kermit/kermit.zip/archives/cku190.tar.Z/cku190.tar/ckcker.bwr

Text File | 1994-11-24 | 59KB | 1,215 lines

CKCKER.BWR          "Beware File" for C-Kermit Version 5A        -*- text -*-

As of C-Kermit version:  5A(190)
This file last updated:  October 4, 1994

Authors: Frank da Cruz and Christine M. Gianone, Columbia University.

  Copyright (C) 1985, 1994, Trustees of Columbia University in the City of New
  York.  The C-Kermit software may not be, in whole or in part, licensed or
  sold for profit as a software product itself, nor may it be included in or
  distributed with commercial products or otherwise distributed by commercial
  concerns to their clients or customers without written permission of the
  Office of Kermit Development and Distribution, Columbia University.  This
  copyright notice must not be removed, altered, or obscured.

Report problems, suggestions, fixes, etc, to Frank da Cruz:

  Columbia University Academic Information Systems
  612 West 115th Street, New York, NY  10025  USA
  Email: [e-mail]

C-Kermit 5A is documented in the book "Using C-Kermit" by Frank da Cruz and
Christine M. Gianone, 1993, Digital Press / Butterworth-Heinemann, Woburn, MA,
USA, ISBN 1-55558-108-0.  Price: US $34.95.  Available in book and computer
stores, or order by phone, call Columbia University at [phone], or
Butterworth-Heinemann at [phone].  A German edition is available from
Verlag Heinz Heise in Hannover, Germany.

NOTE: Some changes have been made to C-Kermit since the 5A(188) release.
These are described in detail in the file CKCKER.UPD, which can be used as
a supplement to "Using C-Kermit".


WHAT IS IN THIS FILE

This is the "beware file" for C-Kermit.  It contains hints and tips,
frequently asked questions (and answers), troubleshooting advice, limitations
and restrictions, known bugs, etc, that apply to all C-Kermit variations.
This file is supplemented by a system-specific "beware file" for each major
system where C-Kermit runs:

  ckuker.bwr - All variations of UNIX: HP-UX, AIX, SCO, Solaris, etc.
  ckoker.bwr - IBM OS/2
  ckvker.bwr - Digital Equipment Corporation VMS and OpenVMS
  cklker.bwr - Stratus VOS
  ckdker.bwr - Data General AOS/VS
  ckmker.bwr - Apple Macintosh
  ckiker.bwr - Commodore Amiga
  cksker.bwr - Atari ST
  ck9ker.bwr - Microware OS-9

This file contains the following sections:

  THE C-KERMIT COMMAND PARSER
  MULTIPLE SESSIONS
  NETWORK COMMUNICATION
  THE SERVICES DIRECTORY
  MODEMS AND DIALING
  DIALING HINTS AND TIPS
  TERMINAL EMULATION
  KEY MAPPING
  THE TRANSMIT COMMAND
  FILE TRANSFER
  SCRIPT PROGRAMMING


THE C-KERMIT COMMAND PARSER

When using the command-line processor ("kermit -l /dev/tty00 -b 19200", etc),
note that in some cases the order of the command-line options makes a
difference, contrary to the expectation that order of command-line options
should not matter.  In this case, the -b option must be given after the -l
option if it is to have any effect.

If you specify an alternate initialization file on the command line (using the
-y option) and the file doesn't exist or can't be opened, no error is reported.

In the interactive command parser:

 . VMS-style command editing (arrow keys, etc) is not supported.
 . EMACS- or VI-style command line editing is not supported.
 . Editing keys are hardwired (Ctrl-U, Ctrl-W, etc).

If you interrupt C-Kermit before it has issued its first prompt, it will exit.
This means that you cannot interrupt execution of the initialization file, or
of an "application file" (file whose name is given as the first command-line
argument), or of an alternative initialization file ("-y filename"), and get
to the prompt.  There is, however, one exception to this rule: you *can*
interrupt commands -- including TAKE commands -- given in the '-C "command
list"' command-line argument and -- if there were no action commands among the
command-line arguments -- you will be returned to the C-Kermit prompt.  So,
for example, if you want to start C-Kermit in such a way that it executes a
command file before issuing its first prompt, and you also want to be able to
interrupt the command file and get to the prompt, include a TAKE command for
the desired command in the -C argument, for example:

   kermit -C "take dial.scr"

Reportedly, if you attempt to interrupt Kermit while it is executing its
initialization file, and you do this rapidly enough, e.g. by sending a
constant stream of Ctrl-C's at a very high rate of speed, depending on the
underlying operating system (reported only on a couple versions of UNIX),
duplicate Kermit processes might be created -- cause unknown, cure unknown,
workaround: don't do it.

If you use the backslash (\) prefix to enter a control character, space, or
question mark into a command literally, the backslash disappears and is
replaced by the quoted character.  If it was a control character, it is shown
as a circumflex (^).  This allows editing (backspace, delete, Ctrl-W) to work
correctly even for control characters.

The only way to include a comma literally in a macro definition -- as opposed
to having it separate commands within the definition -- is to enter its ASCII
value (44) in backslash notation, e.g.:

  DEFINE ROWS MODE CO80\{44}\%1

If you quote special characters in a filename (e.g. in the SEND command),
filename completion may seem to work incorrectly.  For example, if you have a
file whose name is a*b (the name really contains an asterisk), and you type
"send a\\*<ESC>", the "b" will not appear, nor will Ctrl-R redisplay the
completed name correctly.  But internally the file name is recognized anyway.

Question-mark help does not work during execution of an ASKQ command.  The
question marks are simply accepted as text.

The maximum length for a variable name is 20 characters.  For array
declarations and references, that includes the subscript.  So, for example:

  \%a[\m(max_services)]

is one character too long (this can be changed by redefining the symbol VNAML
in ckuusr.h and recompiling C-Kermit).

Some other maximums to watch out for:      Symbol    Value Defined in

 Nesting level for command files:           MAXTAKE      30  ckuusr.h
 Nesting level for macros:                  MACLEVEL     50  ckuusr.h
 Nesting level for FOR / WHILE loops:       FORDEPTH     10  ckuusr.h
 Number of macros:                          MAC_MAX     256  ckuusr.h
 Size of INPUT buffer:                      INPBUFSIZ   256  ckuusr.h
 Maximum files to match a wildcard:         MAXWLD   varies  ck?fio.c
 Filespecs in MSEND command:                MSENDMAX    100  ckuusr.h
 Length of MSEND or GET string:             FSPECL      300  ckuusr.h
 Length for GOTO target label:              LBLSIZ       50  ckuusr.h
 Number of characters in a command:         CMDBL      1024  ckucmd.h
 Number of chars in a field of a command:   ATMBL       256  ckucmd.h
 \fexecute() recursion depth limit:         CMDDEP       20  ckucmd.h

ASK and ASKQ strip leading and trailing spaces from what the user types.  This
happens way down deep in the command parser -- it's nothing special about ASK
and friends.  The only way around this that works in both C-Kermit and MS-DOS
Kermit is for the user (the one who is responding to the ASK prompt) to type
(the first) leading space as "\32" and the (final) trailing space as "\32".
In this example, the password begins with 2 leading blanks and ends with two
trailing blanks, and "Passwd:" is the ASK prompt:

 Passwd:\32 secret \32

Of course, the user could also type *all* blanks as \32.

In OUTPUT commands only, \B and \\B send a BREAK signal, and \L and \\L send a
Long BREAK signal, and \N and \\N send a NUL (ASCII 0).  BREAK and Long BREAK
are special signals, not characters, and NUL is a character that normally
cannot be included in a C string, since it is the C string terminator.

If you really want to output a backslash followed by a B, an L, or an N (as is
needed to configure certain modems, etc), use "output \fliteral(\B)" (can be
abbreviated, e.g. "out \flit(\B)") -- same for L or N.  You can also use
"output \\\\B" (yes, four backslashes); same for L or N.

MULTIPLE SESSIONS

C-Kermit does not support multiple sessions.  When you SET LINE (or SET PORT,
same thing) to a new device, or SET HOST to a new host, the previous SET LINE
device or network host connection is closed, resulting in hangup of the modem
or termination of the network connection.  In windowing environments like
HP-VUE, NeXTSTEP, OS/2, etc, you can run separate copies of Kermit in different
windows to achieve multiple sessions.

To achieve multiple sessions through a single serial port (e.g. when dialing
up), you can install SLIP or PPP on your computer and then use C-Kermit's
TCP/IP support over the SLIP or PPP connection, assuming you also have
TCP/IP networking installed on your computer.

On UNIX systems that support the "term" program, you can establish a
connection to another UNIX system with C-Kermit and then achieve multiple
sessions using "term" client programs like trsh (see ckuker.bwr and the term
documentation for details).


NETWORK COMMUNICATION

On a TCP/IP TELNET connection, you should normally have PARITY set to NONE and
(except in VMS C-Kermit) FLOW-CONTROL also set to NONE.  If file transfer does
not work with these settings (for example, because the remote TELNET server
only gives a 7-bit data path), use SET PARITY SPACE.  Do not use SET PARITY
MARK, EVEN, or ODD on a TELNET connection -- it interferes with TELNET
protocol.

If echoing does not work right after connecting to a network host or after
dialing through a TCP/IP modem server, it probably means that the TELNET
server on the far end of the connection is executing the TELNET protocol
incorrectly.  After initially connecting and discovering incorrect echoing
(characters are echoed twice, or not at all), escape back, give the
appropriate SET DUPLEX command (FULL or HALF), and then CONNECT again.
For a consistently misbehaving connection, you can automate this process in
a macro or TAKE file.

TELNET sessions are treated just like serial communications sessions as far as
"terminal bytesize" and "command bytesize" are concerned.  If you need to view
and/or enter 8-bit characters during a TELNET session, you must tell C-Kermit
to SET TERMINAL BYTESIZE 8, SET COMMAND BYTESIZE 8, and SET PARITY NONE.

If you SET TERMINAL DEBUG ON or SET DEBUG SESSION (same thing), TELNET
protocol negotiations will be displayed on your screen.  But most of the
interesting negotiations happen at the time the SET HOST or TELNET command
is given, before CONNECT mode is entered, so you won't see them on your
screen.  However, you can still capture them in the debug log ("log debug").

For details about TCP/IP, NETBIOS, and Named Pipes communication for OS/2
C-Kermit, see the CKOKER.BWR file.


THE SERVICES DIRECTORY

Until edit 190, the login macros (such as UNIXLOGIN, VMSLOGIN, etc), which are
used in the services directory, had their respective system prompts
hard-coded, so if the prompt on the system you were logging in to differed
from the one in the macro, the macro would time out and report failure (even
though it actually did log you in).  These macros have been changed in edit
190 to allow you to override the default prompt.  As explained on pp.297-301
of "Using C-Kermit", the format of a services directory entry is:

  entry-name  login-macro-name  user-id  connection-macro-name + arguments

For example:

  chemistry   vmslogin   ivan   call hayes com1 2400 7654321

If you want to specify the system prompt to look for after logging in, you
can do it by grouping it after the login macro name in braces, like this:

  chemistry   {vmslogin CHEM:}  ivan   call hayes com1 2400 7654321

For reference, here are the standard login macros and the default prompts:

  UNIXLOGIN     \13\10$\32  (i.e. CR, LF, dollar sign, space)
  VMSLOGIN      \13\10$\32  (ditto)
  CISLOGIN      CompuServe Information Service
  DOWLOGIN      ENTER QUERY
  VMLINELOGIN   (Not applicable)
  VMFULLOGIN    (Not applicable)

See the CKCKER.UPD file for a fuller explanation of the services directory.


MODEMS AND DIALING

The list of modem types supported by C-Kermit is obtained by typing:

  set modem ?

at the C-Kermit> prompt.  If you have a high-speed, error-correcting,
data-compressing modem, you should generally use the following settings:

  set speed 57600 ; Or 38400, the highest supported by both Kermit & the modem
  set dial speed-matching off ; Use speed buffering.
  set flow rts/cts            ; Use hardware flow control.
  set dial mnp on             ; Enable error-correction and compression.

DIAL MNP (which is actually a misnomer, because it applies to error correction
and compression in general, including V.42 and V.42bis) is OFF by default
because if you use an MNP modem to call a non-MNP modem, your MNP modem will
send MNP protocol messages to the other modem, but the other modem will treat
them as ordinary data and pass them through to the host.  This usually results
in your host session being locked up (e.g. autobaud to wrong speed, invalid
login, etc).  Also note that, at present, the SET DIAL MNP command is
effective only for US Robotics and Telebit modem types.

Always use hardware flow control if it is available (some operating systems
do not support it).  If it is not, use Xon/Xoff ("software") flow control
between your computer and the modem, which means you must tell C-Kermit to
"set flow xon/xoff" and you must configure your modem for this too.

If you have a modem that is not directly supported by C-Kermit, you can define
a new modem type for it.  For example, suppose you have a Practical
Peripherals PM14400FXMT V.32bis/V.42/V.42bis/MNP modem and you want to take
full advantage of its features.  You can dial with this modem, taking
advantage of the support for Hayes-like modems that is already built into
C-Kermit, but substituting an initialization string particular to the PP14400:

  set modem hayes        ; Use Hayes-like dialog
  set line <whatever>        ; Select the device your modem is on
  set speed 57600        ; Use high speed
  set dial speed-matching off    ; Lock the speed
  set flow rts/cts        ; Use hardware flow control
  set dial init ATQ0S2=43N1S37=11&K3&Q5S36=7S46=2S82=128\13

where:

  Q0         Result codes enabled
  S2=43      Escape character is "+"
  N1         Enable modulation negotiation
  S37=11     Enable V.32.bis
  &K3        Enable RTS/CTS (only if your C-Kermit version supports it)
  &Q5        Enable error correction
  S36=7       and compression with
  S46=2       automatic speed buffering
  S82=128    Pass BREAK signals through

This can be turned into a dialing macro, PPDIAL, which you can use in place of
the DIAL command:

define PPDIAL -
  set modem hayes, -
  set line <whatever>, -          ; Change this appropriately
  set speed 57600, -
  set dial speed-matching off, -
  set dial init ATQ0S2=43N1S37=11&K3&Q5S36=7S46=2S82=128\13, -
  dial \%1, -
  if success set flow rts/cts, -  ; (If your C-Kermit version supports it)
  else end 1

If you put this definition into your CKERMOD.INI (or .mykermrc) file, then
it will always be available for you to use, for example:

  C-Kermit> ppdial 7654321

And you can also use REDIAL in the normal way.

See your modem manual for details about initialization strings.  Most modern
modems should be set up as in the example above but, naturally, the specific
modem commands differ.

Here are some sample modem initialization strings that should obtain settings
equivalent to those made for the PP14400, for various other types of
high-speed, error-correcting, data-compressing modems that are not
specifically supported by Kermit's DIAL command.  The maximum speed is shown
after the modem name.  These are offered in a form suitable for use in the SET
DIAL INIT-STRING command (modem-command backslashes doubled, \13 at the end
for carriage return), but with no guarantees -- see your modem manual for
explanations of the commands and for further details.  Each of these
initialization strings attempts to:

 . Start modulation negotation at V.32bis (14400bps), enabling fallback.
 . Fix the interface speed at 57600 or 38400 bps.
 . Enable error correction and compression, enabling fallback.
 . Allow BREAK signals to be passed through transparently.

AT&T DataPort 14400, 57600 bps:
  AT Q0 X6 &C1 &D2 &Q0 S84=0 \\Q3 %B14400 S41=1 S78=0 \\N7 %C1 \\K5\13

Boca 14.4 Faxmodem, 57600 bps:
  AT Q0W1&D2X4 S95=47 F10 S37=11 N1 &K3 S82=128 &Q5 S36=7 S46=138 \\N3 S48=7\13

Hayes Ultra 144, 38400 bps:
  AT Q0W1X4 S87=28 &D2 S95=46 S37=11 N1 &K1 &K3 &Q5 S36=7 S38=1 S46=2 S48=7\13

Multitech MT1432, 57600 bps:
  AT Q0 &Q1 X4 $SB57600 $MB14400 &E4 %E1 &E1 &E15 $BA0\13

Practical Peripherals 14400FXMT, 57600 bps:
  AT Q0 W1 S95=47 &D2 X4 S2=43 N1 S37=11 &K3 &Q5 S36=7 S46=2 S82=128\13

USR Sportster or Courier, 57600 bps:
  AT Q0 &S0 X4 &A3 &D2 &B1 &H1 &R2 &N0 &K1 &M4 &Y3\13

Zoom Telephonics 14400, 57600 bps:
  AT Q0 W1 &D2 S95=47 X4 S37=11 &K3 S82=128 &Q5 S36=7 S46=138 S38=1\13

CAUTION: Reportedly, these strings might be too long for some modems.  If
that is the case with yours, you can do one of the following:

 . Shorten the string by removing spaces and/or commands that are not
   necessary because they correspond to your modem's normal settings.

 . Change your dialing macro to simply OUTPUT these commands in small
   groups before issuing the DIAL command.

DIALING HINTS AND TIPS

Remember: In many C-Kermit implementations (depending on the underlying
operating system -- mostly OS/2 and System-V-based UNIX versions), you can't
CONNECT to a modem and type the modem's dialing command (like "ATDT7654321")
manually, unless you first tell C-Kermit to:

  SET CARRIER OFF

This is because (in these implementations), the CONNECT command requires the
modem's Carrier Detect (CD) signal to be on, but the CD signal doesn't come on
until after dialing is complete.  This requirement is what allows C-Kermit to
pop back to its prompt automatically when the connection is hung up.  See the
description of SET CARRIER in "Using C-Kermit".

Similarly, if your dialed connection drops when CARRIER is set to AUTO or ON,
you can't CONNECT back to the (now disconnected) screen to see what might
have happened unless you first SET CARRIER OFF.

Automatic redialing:  Here is a simple macro that dials and keeps redialing
every thirty seconds until it gets an answer.  Obviously, it can be elaborated
with messages, counters, etc:

  define keep_on_dialing dial \%1, while failure { sleep 30, redial }

Don't SET FLOW RTS/CTS if your modem is turned off, or if it is not presenting
the CTS signal.  Otherwise, the serial device driver might get stuck waiting
for this signal to appear.  When dialing, it is better to give the SET FLOW
RTS/CTS command after the DIAL command than before it.

Here are a few points to clarify the purpose of SET DIAL SPEED-MATCHING:

 1. This command does not do anything at all to the modem.  Rather, it is used
    to inform C-Kermit about the modem's configuration: whether the modem's
    interface speed is "fixed", or it changes its interface speed when a
    connection is made.  In the latter case, C-Kermit changes its own speed in
    response to the speed given in the modem's CONNECT message.  By default,
    SPEED-MATCHING is ON, so Kermit does indeed attempt to change its speed.
    If your modem is set to have a fixed interface speed, you must SET DIAL
    SPEED-MATCHING OFF.

 2. When DIAL SPEED-MATCHING is ON:

    (a) Your modem must be configured to report its *interface* speed in the
        CONNECT message, rather than the connection (modulation) speed.

    (b) Your computer (and C-Kermit) must support all connection speeds that
        might be reported by your modem.  SET SPEED ? will give you a list of
        the speeds that your version of C-Kermit knows about.

 3. If conditions (a) and (b) cannot be satisfied, then you must:

    (a) Configure your modem to lock its interface speed

    (b) Tell C-Kermit to SET DIAL SPEED-MATCHING OFF

To illustrate, suppose you have a V.32bis modem.  When it connects to a
remote V.32bis modem, it might issue a message like:

  CONNECT 14400

But 14400 bps is not a speed that is supported by certain operating systems
and so C-Kermit might fail to adjust its speed according to this report.
Therefore, you must lock the modem's interface speed at a higher speed (such
as 19200, 38400, or 57600) that is supported by C-Kermit, set C-Kermit to the
same speed, and tell C-Kermit to SET DIAL SPEED-MATCHING OFF.

If you have a high-speed, error-correcting, data-compressing, speed-buffering
modem, you should always SET DIAL SPEED-MATCHING OFF, and you should fix the
modem's interface speed as high as possible, preferably four times higher than
its maximum connection (modulation) speed to allow compression to work at full
advantage.  In this type of setup, you must also have an effective means of
flow control enabled between C-Kermit and the modem, preferably hardware
(RTS/CTS) flow control.

C-Kermit knows about a large number of modems, depending on how it was built
(type "set modem ?" and "show features" for further info).  This knowledge is
imbedded in the SET MODEM and DIAL commands.  If you are having trouble
dialing your modem, SET DIAL DISPLAY ON to watch the dialing interactions
between C-Kermit and your modem.  Consult pages 65-66 of "Using C-Kermit" for
modem-dialing troubleshooting instructions.

If it takes your call longer to be completed than the timeout interval that
C-Kermit calculates, you can use the SET DIAL TIMEOUT command to override
C-Kermit's value.  But beware: the modem has its own timeout for completing
the call.  If it is a Hayes-like modem, C-Kermit adjusts the modem's value
too by setting register S7.  But the maximum value for S7 might be smaller
than the time you need!  In that case, C-Kermit sets S7 to 0, 255, or other
(modem-specific) value to signify "no timeout".

WARNING: Certain modems might have a maximum dial timeout shorter than what
Kermit expects it to be.  If Kermit attempts to set register S7 to a value
higher than your modem's maximum, the modem will say "ERROR" and you will get
a "Failure to initialize modem" error.  In that case, use SET DIAL TIMEOUT to
override C-Kermit's calculation of the timeout value with the highest value
that is legal for your modem, e.g. 60.

How to DIAL from a TCP/IP reverse terminal server (modem server):

 1. (only if neccessary) SET TELNET ECHO REMOTE
 2. SET HOST <terminal-server-ip-name-or-address> [ <port> ]
 3. SET MODEM <modem-type>
 4. (only if necessary) SET DIAL HANGUP OFF
 5. DIAL <phone-number>

The order is important.

Although various modem-dialing strings are configurable, the DIAL MODEM-HANGUP
string is not.  For Hayes and Hayes-like modems it is ATQ0H0; the Q0 is to
ensure that a result code is produced.  In case the Q0 interferes with your
normal setup (for example, if you keep your modems set to Q2), and dropping
the connection does not restore the normal connection, you can define Kermit's
ON_EXIT macro to send the appropriate modem configuration commands when Kermit
exits, for example:

  define on_exit if > \v(local) 0 output ATQ2\13

The SET DIAL KERMIT-SPOOF command works only for Telebit and US Robotics modem
types; it is OFF by default.  You may wish to experiment with large packets
(1K or greater) and various window sizes with spoofing disabled in the modem.
In most situations the transfer rates achieved by Kermit with sliding windows
and long packets are better than with protocol spoofing turned on.  Also,
attribute (A) packets are not passed by current Telebit modems with spoofing
enabled so if they are desired spoofing must be turned off.

DEC modems...  Reportedly, these don't work right when connected to a DEC
terminal server -- result codes are never reported (on the other hand, this
might be a modem configuration problem).  Dialing "by hand", "blind" still
works.  Also, reportedly "For people who do have DEC modems directly connected
to DEC computers the DF03, DF100-series, and DF200-series modem dialers should
work.  The only thing that is not straightforward is that the DF124-CA,
DF124-CM modems must use the the DF200-series since they speak Digital Modem
Command Language (DMCL) and AT commands.  The Digital Scholar Plus is a DF242
so it uses the DF200-series."

If C-Kermit's dialing methods are insufficient for your purposes, you can
write a C-Kermit script program to do the dialing.  Or you can use (or write)
another program to accomplish the dialing, and then run C-Kermit "underneath"
your dialing program by giving it the open file descriptor:

  kermit -l <n> -m unknown

where <n> is the numeric file desciptor.  (This feature is available in the
UNIX and OS/2 versions of C-Kermit.)  Or you can modify the ckudia.c module.

NOTE: When you give a SET DIAL DIRECTORY command, C-Kermit keeps your dial
directory file open until you give another SET DIAL DIRECTORY command, or
until you EXIT.  So, for example, you can't edit the dialing directory while
you have it open.  If you want to edit the dialing directory from within
Kermit, you can close it by giving a SET DIAL DIRECTORY command with no file
name.  Then you can open it again with SET DIAL DIRECTORY <filename>.

HAYES AND COMPATIBLE MODEMS

C-Kermit should work correctly with Hayes and other modems that use the AT
command set.  These include Hayes 1200, Hayes 2400, and Hayes 9600 bps modems,
compatibles, as well as Telebit and HST modems.  See the next section for
Telebit information.  C-Kermit sends AT commands to the modem and then reads
the modem's response.  The software is designed to work whether the modem is
configured to echo its commands (E1) or not (E0), and whether it replies with
numeric (V0) or word (V1) result codes.  C-Kermit does not change the echoing
state or result code mode of the modem.  However, C-Kermit issues the Q0
command to the modem to ensure that it *does* produce result codes.  C-Kermit
assumes the modem's Command Line Terminator (S3) is 13 (carriage return).  If
it isn't, C-Kermit's dialog with the modem probably won't work correctly.


TELEBIT MODEM DIALING SUPPORT

There are numerous Telebit modem models, with differing capabilities and
features.  C-Kermit tries to support them all in a model-independent way.
To use a Telebit modem, any model, SET MODEM as follows:

TELEBIT
  Dial and attempt to connect using the highest protocol appropriate to
  the interface speed between the computer and the modem, and fall back
  automatically to the highest protocol and speed supported by the answering
  modem.  For example, if your interface speed is 19200 bps and you have a
  PEP-capable Telebit, it will start in PEP mode, fall back to one of the
  2400-bps standards, then one of the 1200 bps standards, etc, depending on
  its configuration (see your Telebit manual).

PEP-TELEBIT
  Dial in PEP mode, and connect only if the remote modem answers in PEP mode.
  Does not work with Telebit models that do not support PEP.  See Table III.

V32-TELEBIT
  Dial in V.32 mode (9600 bps), fall back from there.  Works only with Telebit
  models that support V.32; see Table III.  NOTE: V.32 calls are supposed to
  work no matter what your interface speed is, but it has been observed that
  when calling certain non-Telebit V.32 modems, the connection is not made
  successfully unless C-Kermit's interface speed to the Telebit is 9600.

V42-TELEBIT
  Enable V.42 error correction, allowing fallback to MNP, and from there to
  direct (no error correction).  NOTE: Fallback to MNP from V.42 is allowed
  even if DIAL MNP-ENABLE is OFF.  Works only with Telebit models supporting
  V.42 error control.  See Table III.

SLOW-TELEBIT
  Dial at 2400 bps (V.22bis), fall back from there.

Before attempting to use Telebits at high speeds, there is one problem you
should be aware of: Most Telebit models do not "autobaud" at speeds higher
than 19200 or 38400.  If you want to make a high-speed call on such a modem,
you must access it first at a lower speed, then give it a command to change to
a higher speed, and then change Kermit's speed to match.  For example, on the
Telebit T3000:

  C-Kermit> set speed 19200
  C-Kermit> connect
  AT                           (make sure it can read you)
  OK                           (it can)
  ATS51=7                      (change it to 57600 bps)
  OK                           (it says OK, then changes its speed)
  ^\c                          (escape back to Kermit)
  C-Kermit> set speed 57600    (set Kermit to agree)

Of course, you can automate this process using a script program.  Or if you
always want to dial out at 57600, you can save this setting in the modem,
and then it will always use this speed (and won't autobaud any more).

Telebit modems come in many models that differ not only as to features but
also which commands control which features.  The features, commands, and
acceptable S-register values (and their meanings) can vary not only among
models, but even among different ROM versions on the same model.  Rather than
have dozens of separate SET MODEM TELEBIT-xxx commands, C-Kermit queries the
modem for its model number with an ATI command, and then adjusts its modem
commands accordingly.  Responses to the ATI command are shown in Table I.


---------------------------------------------------------------------------
Table I: Telebit Modem ATI Command Responses
---------------------------------------------------------------------------
  ATI  Model Numbers           Examples
  ---  -------------           --------
  123                          Telebit in "total Hayes-1200" emulation mode
  960                          Telebit in Conventional Command (Hayes) mode
  961  RA12C                   IBM PC internal original Trailblazer
  962  RA12E                   External original Trailblazer, DCA Fastlink,
                                 or Racal-Milgo RM1822
  963  RM12C                   Rackmount original Trailblazer
  964  T18PC                   IBM PC internal Trailblazer-Plus (TB+)
  965  T18SA, T2SAA, T2SAS     External TB+, T1600, T2000, T3000, WB, and later
                                 or Ven-Tel Pathfinder EC18K (see below)
  966  T18RMM                  Rackmount TB+
  967  T2MC                    IBM PS/2 internal TB+
  968  T1000                   External T1000
  969  ?                       QBlazer
  971  T25SA                   External T2500 or T1500 (see below)
  972  T25RM                   Rackmount T2500
---------------------------------------------------------------------------

Certain incompatible models show the same response to ATI.  The ATI3
command is used to differentiate among them, as shown in Table II.

---------------------------------------------------------------------------
Table II: Telebit Modem ATI3 Command Responses
---------------------------------------------------------------------------
ATI        If ATI3 Response
Response   Contains            Telebit Model Is
--------   -----------------   ----------------
 965       "T1600"             T1600
 965       "T3000"             T3000
 965       "World"             WorldBlazer
 965       "Version B"         TrailBlazer-Plus or T2000 external version 1
 965       "TBSA"              TrailBlazer-Plus or T2000 external version 2
 965       "TBRM"              TrailBlazer-Plus or T2000 rackmount version 2
 965       "DC"                Ven-Tel Pathfinder EC18K (= TB+ version 1)
 971       "T1500"             T1500
 971       (anything else)     T2500
----------------------------------------------------------------------------


The features of the various models and the commands used by Kermit to control
them are shown in Table III.  The commands in the PEP column are used to force
PEP and allow compression (SET MODEM PEP-TELEBIT).  The commands in the V.32
column are used with SET MODEM V32-TELEBIT.  The commands in the V.42 column
are used with SET MODEM V42-TELEBIT.  The commands in the MNP column are used
if SET DIAL MNP-ENABLE is ON and the modem type is TELEBIT, PEP-TELEBIT, or
V32-TELEBIT, SLOW-TELEBIT, but not V42-TELEBIT; if SET MNP-ENABLE is OFF, the
S-registers in the MNP column are set to 0.  The Pass BREAK column shows the
commands used to ensure that the modem passes the BREAK signal through (rather
than treating it as an "escape-to-command-mode" signal).

-------------------------------------------------------------------------------
Table III.  Telebit Modem Features and Commands
------+---------------------+-------+--------+--------+-------------+----------
      |                     |       |        |        |             | Kermit
Model |      PEP            | V.32  |  V.42  | MNP    | Pass BREAK  | Spoof
------+---------------------+-------+--------+--------+-------------+----------
TB    | S50=255 S110=1      |  No   |  No    | S95=2  |    S54=3    | PEP only
TB+   | S50=255 S110=1      |  No   |  **    | S95=2  |    S54=3    | PEP only
T2000 | S50=255 S110=1      |  No   |  **    | S95=2  |    S54=3    | PEP only
T1000 | S50=255 S110=1      |  No   |  No    | S95=2  |    S54=3    | PEP only
T2500 | S50=255 S110=1      | S50=6 |  No    | S95=2  |    S54=3    | PEP only
T1500 |      No             | S50=6 |  **    | S95=2  |    S54=3    | PEP,V.32
------+---------------------+-------+--------+--------+-------------+----------
T1600 |      No             | S50=6 | S180=2 | S180=3 | S61=0 S63=0 | PEP,V.32
T3000 |      No             | S50=6 | S180=2 | S180=3 | S61=0 S63=0 | PEP,V.32
QB    |      No             | S50=6 | S180=2 | S180=3 | S61=0 S63=0 | No
WB    | S50=255S190=1S191=7 | S50=6 | S180=2 | S180=3 | S61=0 S63=0 | PEP,V.32
------+---------------------+-------+--------+--------+-------------+----------
**  For V.42 error control: "S50=0 S95=2 S97=1 S98=3 S106=1".

All models but the QBlazer support Kermit spoof (but see below).

Group I (old command set):

          TB = Original TrailBlazer (PEP, MNP, V.22bis, V.22, Bell 212A & 103)
         TB+ = TrailBlazer-Plus = TrailBlazer + V.42 (but only in new ROMs)
       T1000 = TrailBlazer-Plus, speed <= 9600, no PEP compression
       T2000 = TrailBlazer-Plus + SDLC (not used by Kermit, so same as TB+)
       T2500 = TrailBlazer-Plus + V.32 (9600 bps)
       T1500 = T2500 minus PEP

Group II (new command set):

       T1600 = V.32, MNP, V.22bis, V.22, V.23, Bell 212A & 103
QB = QBlazer = T1600 without Kermit spoof and minus some other options
       T3000 = T1600 + V.32bis (14400 bps)
 WorldBlazer = T3000 + PEP + LZ and V.42bis compression + 76800 & 115200 bps.

C-Kermit does not attempt to control whether the modem changes its interface
speed to match the connection speed -- that is up to you; you can configure
the modem any way you prefer (using S51 or, to some extent on new-style modems
S180 and S181), but make sure that the modem's configuration agrees with
C-Kermit's DIAL SPEED-MATCHING setting.  When DIAL SPEED-MATCHING is ON (the
default), C-Kermit changes its interface speed automatically according to the
speed reported in the modem's CONNECT message; when it is OFF, C-Kermit does
not change speed.

Most Telebit modems do not autobaud at speeds above 9600 or 19200 bps unless
specially configured to do so, and even then most (maybe all) models will not
autobaud at all at 57600 bps.  Thus, to make a high-speed modem call with
a Telebit, follow these steps:

  set modem telebit
  set line <whatever>
  set speed 19200
  connect

Now type AT and carriage return to make sure you get an OK result.  Then type:

  ats51=7

and then carriage return.  This changes the Telebit's interface speed to
57600 (use ats51=6 if your modem's or computer's top speed is 38400).
Now escape back to Kermit and give these commands:

  set speed 57600 ; or 38400
  set dial speed-matching off
  set dial mnp on

and now you can place a high-speed, error-correcting, data-compressing call.

The DIAL KERMIT-SPOOF command is only effective for the Telebit models that
supply a Kermit spoof, that is, all but the QBlazer.  If the Telebit model is
TrailBlazer, TrailBlazer-Plus, T1000, T2000, or T2500, PEP mode is forced even
if your SET MODEM command specified a Telebit modem type other than
PEP-TELEBIT, because the Kermit spoof only works in PEP mode on those models.
On the other models supporting the Kermit spoof, it works on both PEP
connections and V.32 MNP (but not V.42) connections.  Thus, you might also
have to SET MODEM MNP-ENABLE ON in order to get the Kermit Spoof to work on
these newer models when making a V.32 connection.

SHOW DIAL does not show the complete initialization string for Telebit modems.
Telebit modems are initialized in several steps, and the initialization
command depends upon your current communication parameters, which model of
Telebit modem you have (which C-Kermit learns during the modem initialization
process), and other factors.  If you use the SET DIAL INIT-STRING command to
change the initialization string, this disables the multistep process and uses
only the string that you have specified.

If you want to use the built-in multi-step process, but you also want to
override one or more of the settings that are done in this process, or add
additional settings, you can use SET DIAL DIAL-COMMAND to add commands to the
dial string (which is normally ATD%s\13), for example "SET DIAL DIAL-COMMAND
AT&C1&D2S181=1DT%s\13".

DIALING AND FLOW CONTROL

If you have SET FLOW to any of the hardware options supported by your version
of C-Kermit, such as RTS/CTS, and if C-Kermit knows how to set the flow
control on your modem, it will do this as part of the DIAL command.  Caution:

 . If C-Kermit's FLOW-CONTROL setting is Xon/Xoff or other type of software
   flow control, C-Kermit will not attempt to change your modem's flow control
   setting, since software flow control is most commonly used end-to-end.  One
   way to engage Xon/Xoff flow control directly between C-Kermit and the
   local modem is to change your modem's DIAL INIT-STRING to do it.

 . If your version of C-Kermit does not support SET FLOW RTS/CTS (or other
   hardware options), then C-Kermit will not attempt to change your modem's
   flow control setting.  Change your modem's DIAL INIT-STRING to do it.

Hardware flow control options are presently handled only for Telebit modems.
On other modem types, you can set the flow control outside of Kermit, or
change Kermit's DIAL INIT-STRING.

Most modern modems support RTS/CTS (if they support any hardware flow control
at all), but some computers use different RS-232 circuits for the same
purposes, e.g. DTR and CD, or DTR and CTS.  In such cases, you might be able
to make your computer work with your modem by appropriately cross-wiring the
circuits in the cable connector, for example the computer's DTR to the modem's
RTS, and modem's CD to the computer's CTS.  HOWEVER, C-Kermit does not know
you have done this.  So if you have (say) SET FLOW DTR/CD, C-Kermit will make
no attempt to tell the modem to use RTS/CTS.  You probably did this yourself
when you configured the modem; if not, you can put the appropriate command in
the DIAL INIT-STRING or DIAL-COMMAND.

A "TIES" (Time-Independent Escape Sequence) modem does not require any guard
time around its escape sequence.  The following text:

+++ATH0

if sent through a TIES modem, for example because you were uploading this
file through it, could pop the modem back into command mode and make it hang
up the connection.  Newer versions of the Telebit T1600 and T3000 (version
LA3.01E firmware and later), and all WorldBlazers, use TIES.

Although the probability of "+++" appearing in a Kermit packet is markedly
lower than with most other protocols (see the File Transfer section below), it
can still happen under certain circumstances.  It can also happen when using
C-Kermit's TRANSMIT command.  If you are using a Telebit TIES modem, you can
change the modem's escape sequence to an otherwise little-used control
character such as Ctrl-_ (Control-Underscore):

  AT S2=31

A sequence of three consecutive Ctrl-_ characters will not appear in a
Kermit packet unless you go to extraordinary lengths to defeat more than a few
of Kermit's built-in safety mechanisms.  And if you do this, then you should
also turn off the modem's escape-sequence recognition altogether:

  AT S48=0 S2=255

But when escape sequence recognition is turned off, "modem hangup"
(<pause>+++<pause>ATH0<CR>) will not work, so you should also be sure to SET
DIAL MODEM-HANGUP OFF.


TERMINAL EMULATION

Except for the OS/2 and Macintosh versions, C-Kermit does not emulate any kind
of terminal.  Rather, it acts more or less as a "transparent pipe", passing
the characters you type during a CONNECT session to the remote host, and
sending the characters received from the remote host to your screen.  Whatever
is controlling your keyboard and screen provides the specific terminal
emulation: a real terminal, a PC running a terminal emulator, etc, or (in the
case of a self-contained workstation) your console driver, a terminal window,
xterm, etc.

There are several exceptions to the "transparent pipe" rule:

 - During a TELNET ("set host") session, C-Kermit itself executes the
   TELNET protocol and performs TELNET negotiations.  (But it does not
   perform TN3270 protocol or any other type of 3270 terminal emulation.)

 - If you have changed your keyboard mapping using SET KEY, C-Kermit replaces
   the characters you type with the characters or strings they are mapped to.

 - If you SET your TERMINAL CHARACTER-SET to anything but TRANSPARENT,
   C-Kermit translates your keystrokes (after applying any SET KEY
   definitions) before transmitting them, and translates received characters
   before showing them on your screen.

 - If your remote and/or local TERMINAL CHARACTER-SET is an ISO 646 7-bit
   national character set, such as German, French, Italian, Swedish, etc, or
   Short KOI used for Cyrillic, C-Kermit's CONNECT command automatically skips
   over ANSI escape sequences to avoid translating their characters.  Only
   ANSI/ISO standard (VT100/200/300-like) 7-bit escape sequence formats are
   supported for this purpose, no proprietary schemes like H-P, Televideo,
   Tektronix, etc.

 - If your version of C-Kermit includes SET TERMINAL APC command, then
   C-Kermit's CONNECT command will handle APC escape sequences if TERMINAL
   APC is not set to OFF (which is the default).

If you are running C-Kermit under a console driver, or in a terminal window,
that emulates the VT100, and use C-Kermit to log in to a VMS system, the
console driver or terminal window (not Kermit) is supposed to reply to the
"what are you?" query (ESC Z) from the VAX.  If it doesn't, and you can't make
it do so, then you can (a) live with the "unknown terminal" problem; (b) tell
VMS to SET TERMINAL/DEVICE=VT100; (c) program a key using SET KEY to send the
appropriate sequence and then punch the key at the right time; or (d) use the
VMSLOGIN macro that is defined in CKERMIT.INI to do this for you
automatically.

SET SESSION-LOG { TEXT, BINARY }, which is effective in UNIX and AOS/VS but
not other C-Kermit versions, removes CR, DEL, NUL, XON, and XOFF characters
("Using C-Kermit" neglects to mention that XON and XOFF are removed).  The
TEXT-mode setting is ineffective during SCRIPT command execution, as well as
on X.25 connections.


KEY MAPPING

Except in the OS/2 and Macintosh versions, C-Kermit's key mapping facilities
are limited to normal "ASCII" keys, and cannot be used with function keys,
arrow keys, arcane key combinations, etc.  Since C-Kermit runs on such a wide
variety of hardware platforms (including, for example, more than 300 different
UNIX platforms), it is not possible for C-Kermit to support every conceivable
keyboard under every release of every UNIX (or VMS, or ...) product on every
different kind of computer possibly under all manner of different console
drivers.

In technical terms, C-Kermit uses the read() function to read keystrokes, and
read() returns a single byte (value 0 through 255).  C-Kermit's SET KEY
function applies to these single-byte codes.  "Extended function" keys, such
as F-keys, arrow keys, etc, usually return either a 2-byte "scan code" or else
a character string (such as an escape sequence like "ESC O p").  In both
cases, C-Kermit has no way to tell the difference between such multibyte key
values, and the corresponding series of single-byte key values.  This could
only be done by accessing the keyboard at a much lower level in a highly
system-dependent manner, probably requiring tens of thousands of lines of code
to support even a sampling of the most popular workstation / OS combinations.

However, most workstation console drivers (terminal emulation windows, etc)
include their own key-mapping facility.  For example, on an IBM RS/6000, the
AIXterm program (in whose window you would run C-Kermit) allows rebinding of
the F1-F12 keys to arbitrary strings.  The same might or might not be true of
DECterm windows, Sun "vttool" or "crttool" windows, etc.  Consult the
technical documentation for your workstation or emulator.

The SET KEY command (except in OS/2) does not allow a key definition to be
(or contain) the NUL (\0) character.


THE TRANSMIT COMMAND

Session logging is inactive during the TRANSMIT command, even if you have
given a LOG SESSION command.


FILE TRANSFER

The recovery feature (RESEND command) that was added in edit 190, as noted in
the CKCKER.UPD file, works only for binary-mode transfers.  In order for this
feature to be useful at all, the default for SET FILE INCOMPLETE was changed
from DISCARD to KEEP.  Otherwise an interrupted transfer would leave no
partial file behind unless you had remembered to change the default.  But now
you have to pay closer attention to Kermit's messages to know whether a
transfer succeeded or failed -- previously, if it failed, the file would not
show up on the receiving end at all; in edit 190 and later, you'll get a
partial file which could easily be mistaken for the complete file unless you
change the default back to DISCARD or read the screen messages, or keep a
transaction log.

Watch out for SET FILE COLLISION RENAME, especially when used in conjunction
with recovery.  Recall that this option (which is NOT the default) renames
the incoming file if a file already exists with the same name (the default is
to rename the previously existing file, and store the incoming file with its
own name).  It is strongly recommended that you do not use SET FILE COLLISION
RENAME if you ever intend to use the recovery feature:

 . When the file is first received by C-Kermit, its name will be changed if
   another file already has the same name.  When you RESEND the same file
   after a failure, C-Kermit will probably try to append the re-sent portion
   to the wrong file.

 . Assuming that you get RESEND to work with FILE COLLISION RENAME, C-Kermit,
   when receiving the remainder of the file during a RESEND operation, will
   report back the wrong name.  Nothing can be done about this because the
   name is reported back before the receiving Kermit program finds out that
   it is a recovery operation.

When referring to MS-DOS, Atari ST, OS/2, or other file specifications that
contain backslash characters in a C-Kermit command, you must double each
backslash, for example:

  C-Kermit>get c:\\directory\\foo.txt

This is because backslash is used in C-Kermit commands for introducing special
character codes, variables, functions, etc.  If you are sending this GET
command to another copy of C-Kermit running as a server, for example on OS/2
or the Atari ST, it too treats backslashes as prefix characters, so you will
need 4 (yes, 4) copies of each backslash:

  C-Kermit>get c:\\\\directory\\\\foo.txt

NOTE: But read about the new command, SET COMMAND QUOTING OFF, in CKCKER.UPD
for a way around this.

ANOTHER NOTE: In OS/2 C-Kermit 5A(190), this restriction is lifted as far as
referring to files on the local OS/2 machine.  You can now refer to these
files using natural OS/2 notation, e.g.

  C-Kermit>send c:\letters\oofa.txt


Attempting to cancel local-mode file reception at a very early stage (i.e.
before data packets are exchanged) with X or Z does not work.  Workarounds:
Use E or Ctrl-C instead, or wait until the first data packets are sent.

If C-Kermit is sending a file, remote-mode packet-mode breakout (Ctrl-C Ctrl-C
by default) is not effective until after C-Kermit sends its first packet.  If
C-Kermit is receiving a file or is in server mode, it will be effective right
away.  In the former case, the SET DELAY value determines the earliest time at
which you can break out of packet mode.

Some communication programs have errors in their implementation of Kermit
attribute packets.  If you get an error message from your communication
program like "Attribute error", tell C-Kermit to SET ATTRIBUTES OFF.  Better
yet, switch to a real Kermit program, such as MS-DOS Kermit.

When using C-Kermit to transfer files with the HP48SX calculator, you must
SET FLOW NONE.  The HP48SX does not support flow control, and evidently also
becomes confused if you attempt to use it.

Occasionally, when receiving files in remote mode using a large window
size, attempts to cancel a file (X) can take a long time.

The fullscreen file transfer display will not work right if your terminal type
is set incorrectly, or is not known to the host operating system.  Even when
it does work, it might slow down your file transfers a bit, especially on
high-speed network connections.  On certain small computers, it has been
reported to cause increased disk activity due to swapping or paging.  The
fullscreen display is not particularly useful with speaking or Braille devices.
In these cases, use SET FILE DISPLAY CRT or SET FILE DISPLAY SERIAL.

If you have trouble transferring files over a TCP/IP connection, give the
command:

  SET PARITY SPACE

and try again.  If that doesn't work, also try a shorter packet length.

On the other hand, if file transfers through a TCP/IP connection work, but are
very slow, use a longer packet length, 2000 or more, and also try increasing
the window size.  Also, make sure FLOW is NONE since TCP/IP handles flow
control itself, and XON/XOFF processing only slows things down.

Some communication software claims to implement sliding windows, but does so
incorrectly.  If sliding window transfers fail, set C-Kermit's window size to
the smallest one that works, for example:

  SET WINDOW 1

The UNIX version of C-Kermit discards carriage returns when receiving files
in text mode.  Thus, "bare" carriage returns (sometimes used to achieve
overstriking) are lost.

SET FILE COLLISION BACKUP is the default.  This means:

 - If you send the same file lots of times, there will be many backup files.
   There is no automatic mechanism within Kermit to delete them, no notion of
   a "version retention count", etc.

 - If a file arrives that has the same name as a directory, the file transfer
   fails.  Send the file with another name, or use SET FILE COLLISION RENAME.

SET FILE COLLISION UPDATE depends on the date/time stamp in the attribute
packet.  However, this is recorded in local time, not GMT, and there is no
indication of time zone.  The time is expressed to the precision of 1 second,
but some file systems do not record with this precision -- for example, MS-DOS
records the file date/time only to the nearest 2 seconds.  This might cause
update operations to send more files than necessary.

SET FILE COLLISION OVERWRITE is risky, use it with caution.  Under certain
conditions, the existing file can be deleted even if the incoming file is
refused.

When C-Kermit is receiving files from another Kermit program that has been
given the MAIL or REMOTE PRINT command, C-Kermit follows the current filename
collision action.  This can be disconcerting if the action was (for example)
BACKUP, because the existing file will be renamed, and the new file will be
mailed (or printed) and then deleted.  Kermit cannot temporarily change to
RENAME because the file collision action occurs when the filename packet is
received, and the PRINT or MAIL disposition only comes later, in the Attribute
packet.

The STATISTICS command will produce an incorrect efficiency report if (a) it
does not know the true communication speed (e.g. on a network connection), or
(b) it knows the true serial interface speed to a modem, but the modem is
using a different communication speed with the other modem.  Similarly, in
these circumstances, C-Kermit's automatic calculation of the packet timeout
interval might also be incorrect, which can cause file transfers to fail.  One
solution to the latter problem is to SET SEND and RECEIVE TIMEOUT to
appropriate values for your true communication speed and packet length.

TELNET option negotiations are not handled during file transfer.  So far, no
ill effects have been noted.

Why is Kermit file transfer over a TCP/IP connection slower than FTP?  Because
the Kermit program on the remote end of the connection is not running directly
on a TCP socket, but rather running underneath a TELNET server, usually on a
pseudoterminal and under a login shell, with the vast amounts of per-character
overhead all of that implies.  Future Kermit releases will be able to act
directly as TCP servers, eliminating all this overhead.

Execution of multiple file transfers by C-Kermit from a command file when
in remote mode might exhibit long delays between each transfer.  To avoid
this, just include the command "SET DELAY 0" in your command file before any
of the file-transfer commands.


SCRIPT PROGRAMMING

The CKERMIT.INI file that was originally distributed with C-Kermit 5A(188)
and (189) contained a nonfunctional CISLOGIN (CompuServe Login) macro.
Fixed in CKERMIT.INI dated September 2, 1993, or later.

Remember that ";" and "#" introduce comments when (a) they are the first
character on the line, or (b) they are preceded by at least one blank or
tab.  Thus constructions like:

  INPUT 5 ;
  SCRIPT ~0 #--#--#

must be coded using backslash notation to keep the data from being ignored:

  INPUT 5 \59            ; 59 is the decimal ASCII code for ";"
  SCRIPT ~0 \43--#--#        ; 43 is the decimal ASCII code for "#"

or, more simply:

  INPUT 5 \;                    ; Just quote the semicolon
  SCRIPT ~0 \#--#--#            ; Just quote the "#"

INPUT and REINPUT caseless string comparisons do not work for non-ASCII
(international) characters.  Workaround: SET INPUT CASE OBSERVE.  Even then,
the "lexically less than" and "lexically greater than" operations (IF LLT, IF
LGT) probably won't work as expected.  The same is true for the
case-conversion functions \Flower() and \Fupper().  C-Kermit does not know the
collating sequence for different character sets and languages.  (On the other
hand, it might work depending on such items as how Kermit was linked, whether
your operating supports "locales", etc)

You can't include a NUL character (\0) in C-Kermit command text without
terminating the character string in which it appears.  For example:

  echo In these brackets [\0] is a NUL

will echo "In these brackets [".  This applies to ECHO, INPUT, OUTPUT, and all
other commands (but you can represent NUL by "\N" in an OUTPUT string).  This
is because C-language strings are terminated internally by the NUL character,
and it allows all of C-Kermit's string comparison and manipulation functions
to work in the normal "C" way.

To illustrate:
  INPUT 5 \0
is equivalent to:
  INPUT 5
and:
  INPUT 5 ABC\0DEF
is equivalent to:
  INPUT 5 ABC

INPUT operations discard and ignore NUL characters that arrive from the
communication device, meaning that they do not figure into matching operations
(e.g. A<NUL>B matches AB); they are not deposited in the INPUT buffer
(\v(input)); and they are not counted in \v(incount), with two exceptions:

  1. An arriving NUL character restarts the INPUT SILENCE timer.

  2. An arriving NUL character terminates the INPUT command with the
     SUCCESS condition if the INPUT command was given an empty search
     string.  In this case \v(incount) is set to 1.

Also, the \v(inchar) variable is null (completely empty) if the last INPUT
character was NUL.  That is, there is no way to tell only by looking at
\v(inchar) the difference between a NUL that was INPUT and no INPUT at all.
If the INPUT command succeeded but \v(inchar) is empty, then a NUL character
was input.  Also, \v(incount) will be set to 1.

\v(incount) and \v(inchar) are NOT affected by the CLEAR command.

GOTO can be used sort of like switch/case.  For example, if you know that the
value of \%a is 1, 2, or 3, you can "goto \%a" provided you have labels :1,
:2, and :3.  What it missing, however, is an automatic way to trap failing
GOTOs, similar to the "default:" clause of a C switch() statement.

The following script program:

  set count \ffiles(oofa.*)
  :loop
  send \fnextfile()
  if count goto loop

does not work as expected.  The SEND command (and any other command that
parses a filename, including TAKE) implicitly calls the same internal function
that \ffiles() calls, and thus destroys the file list set up in the first
line.  To accomplish this type of operation: (1) give the wild filespec to
\ffiles(); (2) loop through the file list and assign each filename to an array
element; (3) use the array of filenames in subsequent file-related commands.
Example:

  asg \%n \ffiles(\%1)
  declare \&f[\%n]
  for \%i 1 \%n 1 { asg \&f[\%i] \fnextfile() }
  for \%i 1 \%n 1 { -
    send \&f[\%i] -
  }

Certain settings are local to each command level, meaning that subordinate
command levels (macros or command files) can change them without affecting
their values at higher command levels.  When a new command level is invoked,
the value is inherited from the previous level.  These settings are:

  CASE
  COUNT and \v(count)
  INPUT CASE
  INPUT TIMEOUT
  MACRO ERROR
  TAKE ERROR

This arrangement allows CASE, TIMEOUT, and ERROR settings, which are used to
control automatic exit from a command file or macro upon error, to be
automatically restored when the command file or macro exits.

The COUNT variable follows this rule too, which permits nested SET COUNT /
IF COUNT loops, as in this example in which the inner loop counts down from
the current COUNT value of the outer loop (try it):

  DEFINE INNER WHILE COUNT { WRITE SCREEN {   Inner:}, SHOW COUNT }
  SET COUNT 5
  WHILE COUNT { WRITE SCREEN Outer:, SHOW COUNT, DO INNER }

Keep in mind that an inferior command level cannot manipulate the COUNT
value held by a higher level.  For example:

  DEFINE OOFA SHOW COUNT, IF COUNT GOTO LOOP
  SET COUNT 5
  :LOOP
  OOFA
  ECHO Done

results in an infinite loop; the COUNT value remains at 5 because it is never
decremented at the same level at which it was set.

NOTE: "WHILE COUNT" did not work prior to edit 095 of ckuusr.c, 19 Jan 93.

(End of CKCKER.BWR)