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TOPS-20
X29PAD User's Guide
February 1984
This document describes all the commands and
features of X29PAD. X29PAD is a program that
allows users to initate terminal sessions with
other hosts over a Public Packet Switch
Network.
OPERATING SYSTEM: TOPS-20 V5.1
SOFTWARE VERSION: X29PAD Version 2
First Printing, February, 1984
(C) Digital Equipment Corporation 1984. All Rights
Reserved.
The information in this document is subject to change
without notice and should not be construed as a
commitment by Digital Equipment Corporation. Digital
Equipment Corporation assumes no responsibility for any
errors that may appear in this document.
The software described in this document is furnished
under a license and may only be used or copied in
accordance with the terms of such license.
No responsibility is assumed for the use or reliability
of software on equipment that is not supplied by Digital
or its affiliated companies.
The following are trademarks of Digital Equipment
Corporation:
<TBS>
Contents
iii
Preface
This manual contains information on the program X29PAD. X29PAD is a
program that allows a TOPS-20 user to enter into an interactive terminal
session with a REMOTE-HOST in a PPSN (Public Packet Switching Network).
Other DIGITAL manuals useful to the reader of this manual:
DECnet-20 User's Guide
TOPS-20 PSI User's Guide
iv
CHAPTER 1
INTRODUCTION
Before the advent of Public Packet Switching Networks (PPSN), a user who
wished to access a remote computer system from a terminal had to either
lease a dedicated line from his site to the remote computer system or
connect the terminal to the remote system with a low speed asynchronous
modem through the public telephone network.
Over the past few years PPSNs have grown tremendously as more and more
computer systems have been connected to the network. This growth has
made it easier for users to exchange and distribute information among
many computer systems. The number and diversity of the many database
services offered via the PPSN is testimony to this growth.
With the introduction of the TOPS-20 PSI Gateway it becomes desireable
for tusers on a local TOPS-20 system connected to the PPSN to initiate
an interactive terminal session with a remote computer system (to be
refered to from here on as the REMOTE-HOST) also connected to the PPSN
without having to resort to the use of low speed asynchronous modems or
dedicated leased lines.
X29PAD is a program that allows a user on a TOPS-20 system initate and
carry on an interactive terminal session with a REMOTE-HOST on the PPSN.
The user gains access to the PPSN through the Gateway between the DECnet
network and the X.25 based PPSN.
1-1
CHAPTER 2
X29PAD COMMANDS
2-1
ABORT
Description
The ABORT command stops the transmission of a file to the
REMOTE-HOST.
Format
X29PAD>ABORT (the transmition of the file currently being sent)
Function
The ABORT command allows the user to stop the sending of a file to
the REMOTE-HOST. This command terminates the transfer and closes
the file being sent. The user is left in command mode from which
other commands may be issued.
Notes
An implicit ABORT is done whenever the call to the REMOTE-HOST is
terminated either by the user or because of a network error.
Error messages
%There is no file currently being send
2-2
BREAK
Description
The BREAK command initiates a break sequence and then continues the
call.
Format
X29PAD>BREAK (and continue the call)
Function
The BREAK command causes a break sequence to be initiated. The
actions performed are determined by the ACTION-ON-BREAK PAD
Parameter's value ( X.3 Parameter No. 7 ). After the required
sequence is performed, X29PAD attempts to continue the call. The
call will not be continued if the ACTION-ON-BREAK PAD Parameter is
set to ESCAPE to command mode.
Notes
Some users may wish to disable the BREAK-CHARACTER and causing
breaks to occur by typing the ESCAPE-CHARACTER followed by the BREAK
command. This may be advisable if the user intends to use an editor
such as EMACS on the REMOTE-HOST since most characters are EMACS
commands.
Error Messages
?There is no call to continue
2-3
CALL
Description
The CALL command attempts to establish a connection to a specified
REMOTE-HOST.
Format
X29PAD>CALL argument-1 argument-2 ,
X29PAD-CALL>subcommand
where
argument-1 is either a numeric DTE address or a
REMOTE-HOST name. The REMOTE-HOST
name must have been previously
specified with the DEFINE command.
argument-2 is an optional subaddress (if
argument-1 is a DTE address)
, a comma at the end of the command
instructs X29PAD to enter CALL
subcommand mode to allow you to enter
call specific subcommands
CALL Command Subcommands
ABORT Aborts the current call and returns to
command mode.
CLOSED-USER-GROUP Allows you to supply a
CLOSED-USER-GROUP name for the current
call (or override the default). The
CLOSED-USER-GROUP has a maximum length
of 16 characters.
FACILITIES-DATA Allows you to supply FACILITIES-DATA
for this call (or override the
default). The maximum length of the
FACILITIES-DATA is 63 bytes.
HELP Gives help with the CALL subcommands.
INFORMATION Displays the current call parameters
(either as supplied or defaults that
2-4
will be used).
USER-DATA Allows you to supply USER-DATA for the
outgoing call (or override the
default). The maximum length of the
USER-DATA is 12 bytes.
Function
The CALL command is used to initiate a terminal session with a
REMOTE-HOST. One form of the command is:
X29PAD>CALL remote-host-name
where the remote-host-name has been defined previously using the
DEFINE command. Typing a ? after CALL will list the names of the
remote hosts that have been defined up to that point. Optionally,
you may elect to supply the actual DTE address and subaddress. This
format is:
X29PAD>CALL dte-address dte-subaddress
where dte-address and dte-subaddress are the numeric string of the
REMOTE-HOST you wish to call.
You may enter subcommands by typing a COMMA and a RETURN following
the name or number of the REMOTE-HOST you are calling. Subcommand
mode is used to supply (or modify, if defaults have been set)
certain call related data fields. Specificly, the user may elect to
supply or modify the CLOSED-USER-GROUP data string, the
FACILITIES-DATA string, and the USER-DATA string. Subcommand mode
has the following subcommands:
ABORT CLOSED-USER-GROUP FACILITIES-DATA
HELP INFORMATION USER-DATA
The ABORT subcommand allows the user to exit from the CALL
subcommand mode return to X29PAD command mode without placing the
outgoing call. The format of this subcommand is:
X29PAD-CALL>ABORT (this attempt to place a call)
Any data entered in subcommand mode is lost if the user ABORTS the
call.
The CLOSED-USER-GROUP subcommand allows the user to specify
CLOSED-USER-GROUP data in the form of a quoted string. The format
of this subcommand is:
X29PAD-CALL>CLOSED-USER-GROUP (is) argument
where argument is a quoted string of up to sixteen characters in
length.
2-5
If specified, the CLOSED-USER-GROUP subcommand overrides any default
previously specified by the SET DEFAULT CALL CLOSED-USER-GROUP
command. Also, if specified, data supplied by the user is valid for
a particular call and must be resupplied for any subsequent outgoing
calls.
The FACILITIES-DATA subcommand allows the user to set
FACILITIES-DATA on a per call basis. The format of this subcommand
is:
X29PAD-CALL>FACILITIES-DATA (are) arguments
where the arguments are either octal data in the range 0 to 377 or
quoted ASCII strings. For example, the following subcommand:
X29PAD-CALL>FACILITIES-DATA (are) 1 1 0 0 "A2" 3 21
sets the FACILITIES-DATA string for this call to:
<1><1><0><0>A2<3><21>
Caution
Default FACILITIES-DATA are overridden by data supplied by
the user to the FACILITIES-DATA subcommand to the CALL
command. Issuing the FACILITIES-DATA subcommand without
supplying data clears the FACILITIES-DATA data string for
this call.
The HELP subcommand allows the user to obtain help with the CALL
subcommands without having to abort the current outgoing call and
return to the top command level. The HELP subcommand provides help
with those subcommands available in CALL subcommand mode. The
format of this subcommand is:
X29PAD-CALL>HELP (with) argument
where argument is optional and if supplied is one of the
subcommands.
The INFORMATION subcommand allows the user to examine call data that
has been entered and will be used for the current outgoing call.
The format of this subcommand is:
X29PAD-CALL>INFORMATION (about current CALL parameters)
The INFORMATION subcommand will display any data the user has
supplied in subcommand mode. If a specific parameter has not been
modified by the user in subcommand mode the default data will be
displayed (and noted).
2-6
The USER-DATA subcommand allows the user to set USER-DATA on a per
call basis. The format of this subcommand is:
X29PAD-CALL>USER-DATA (are) arguments
where the arguments are either octal data in the range 0 to 377 or
quoted ASCII strings. For example, the following subcommand:
X29PAD-CALL>USER-DATA (are) 1 1 0 0 "A2" 3 21
sets the default USER-DATA string to:
<1><0><0><0><1><1><0><0>A2<3><21>
Issuing the USER-DATA subcommand without supplying data clears the
default data string.
Caution
Default USER-DATA are overridden by data supplied by the
user to the USER-DATA subcommand to the CALL command. Also,
there is a mandatory four byte string that prefixes any user
supplied data. The string is <1><0><0><0> and indicates to
the REMOTE-HOST that the call is an X.29 call.
If you have not already supplied a network name and password (using
the SET NETWORK command) you will be asked to supply them before the
call to the remote-host will be placed.
Notes
Sometimes X29PAD will not be able to complete a call to a
REMOTE-HOST due to problems in the Public Packet Switching Network
(PPSN). If the cause of the failure is somewhere in the PPSN, the
PPSN will report the error as two numbers, the Network Clear Code
and the Diagnostic Code. X29PAD will try to interpret the Network
Clear Code. However, no attempt will be made to interpret the
Diagnostic Code since the Diagnostic Codes are PPSN specific.
Consult your network vendor's documentation for a description of
these codes. The following example shows a call that failed:
X29PAD>CALL 311061700123
BREAK-CHARACTER (is) CONTROL-X
ESCAPE-CHARACTER (is) CONTROL-\
Calling Remote DTE 311061700123 [FAILED]
?Call not completed - Remote DTE number is out of order
Network clear code #9, diagnostic code #0
Call cleared at 16:14:28-EST on January 27, 1984
Transmitted 0 characters in 0 packets.
Received 0 characters in 0 packets.
X29PAD>
2-7
Error messages
?A connection to a Remote DTE already exists
?Aborting the call and clearing the circuit
?Address string cannot exceed 15 characters
?Address string must be numeric
?Call not completed - Access barred
?Call not completed - Fast select acceptance not subscribed to
?Call not completed - Incompatible destination
?Call not completed - Invalid facility request
?Call not completed - Local procedure error
?Call not completed - Network congestion
?Call not completed - Not obtainable
?Call not completed - Remote DTE number is busy
?Call not completed - Remote DTE number is out of order
?Call not completed - Remote procedure error
?Call not completed - Reverse charging acceptance not subscribed to
?Call not completed - RPOA out of order
?Call not completed - Unknown clear code #
%Circuit cleared at the request of the REMOTE-HOST
?Illegal null string specified
Network clear code #n , diagnostic code #m
?Network name cannot exceed 16 characters
?Network password cannot exceed 16 characters
?Subaddress string cannot exceed 15 characters
?Subaddress string must be numeric
?The port entered an illegal state while waiting for call completion
?The PORT is not RUNNING! The current PORT state is
?The public data network is not running
2-8
?The remote host has refused connection
2-9
CLEAR
Description
The CLEAR command causes the current call to be terminated.
Format
X29PAD>CLEAR (current call)
Function
The CLEAR command directs X29PAD to terminate the current call to a
REMOTE-HOST. Any output from the REMOTE-HOST that has not been
displayed will be lost. X29PAD will display the date and time the
call was cleared along with the number of characters and packets
that were transmitted and received.
Notes
An implicit CLEAR is done whenever the user issues the EXIT command
and there is a call to a REMOTE-HOST in progress.
Error Messages
%There is no call to clear
2-10
CLOSE
Description
The CLOSE command causes logging to be terminated and the log file
to be closed.
Format
X29PAD>CLOSE (log file!)
***** Log file closed at 13:16:28-EST on January 13, 1984 *****
Function
The CLOSE command is used to terminate the logging of a terminal
session previously initiated by the LOG command. A timestamp is
displayed and added to the end of the log file after which the log
file is closed.
Notes
An implicit CLOSE is done whenever the user issues the EXIT command
and logging is in progress.
2-11
CONTINUE
Description
The CONTINUE command causes X29PAD to continue the current call to
the REMOTE-HOST.
Format
X29PAD>CONTINUE (current call)
Function
The CONTINUE command directs X29PAD to reenter communication with
the REMOTE-HOST, displaying information sent from the REMOTE-HOST on
the user's terminal and sending data entered by the user to the
REMOTE-HOST.
Error Messages
?Aborting the call and clearing the circuit
?The PORT is not RUNNING! The current PORT state is xxxxxx
?There is no call to continue
2-12
DEFINE
Description
The DEFINE command allows the user to associate names with the DTE
addresses of REMOTE-HOSTS.
Format
X29PAD>DEFINE (remote-host) name (as DTE number) arg-1 arg-2
where
name is a user chosen string of up to
sixteen characters in length
arg-1 is a numeric string of up to fifteen
digits in length which corresponds to
the network address of the REMOTE-HOST
arg-2 is an optional numeric string which
specifies the subaddress desired
Function
The DEFINE command is similar to the TOPS20 DEFINE command in that
it allows the user to associate names with the dte-addresses od
various REMOTE-HOSTS. This eliminates the need for the user to
remember numerous long numeric strings. The user may remove
REMOTE-HOST definitions by typing a carriage return after giving the
REMOTE-HOST name without specifying a dte-address.
Notes
If a REMOTE-HOST has been previously defined, defining it again will
simply replace the old dte-address with the newly supplied
dte-address.
The command INFORMATION (about) REMOTE-HOSTS will display all
REMOTE-HOSTS that have been defined along with the DTE-address and
(if supplied) DTE-subaddress.
During the processing of a CALL command the DTE-subaddress string is
appended to the DTE-address string. Therefore, calling the
REMOTE-HOST names defined in the following commands:
2-13
X29PAD>DEFINE HOST-A 12345 67
X29PAD>DEFINE HOST-B 1234567
would connect the user to the same destination.
Error Messages
?DTE address may not exceed 15 characters
?DTE subaddress may not exceed 15 characters
?No name given
?No room to add another REMOTE-HOST
2-14
EXIT
Description
The EXIT command causes X29PAD to cease execution and return the
user to the EXEC.
Format
X29PAD>EXIT (from X29PAD)
Function
The EXIT command returns the user to system command mode.
Notes
The EXIT command will cause an implicit CLEAR command to be executed
if a call to a REMOTE-HOST is in progress. This will be followed by
an implicit CLOSE command if logging is being done.
Continuing X29PAD after the user has exited will cause X29PAD to
place the user in command mode without reinitializing itself. All
REMOTE-HOST definitions and defaults remain unchanged.
2-15
HELP
Description
The HELP command gives the user help with X29PAD's commands.
Format
X29PAD>HELP (with) argument-1 argument-2 ... argument-n
where
argument-1 is one of the following:
ABORT BREAK CALL CLEAR CLOSE
CONTINUE DEFINE EXIT HELP INFORMATION
LOG PUSH SEND SET TAKE
X29PAD
argument-2 through argument-n are dependent on argument-1
Function
The HELP command is a hierarchial help facility. The user may
obtain help with all of X29PAD's commands and more detailed
information about various aspects of the commands. Typing a
question mark will give the user a list of subtopics available at
any point in the command string.
2-16
INFORMATION
Function
The INFORMATION command.
Format
X29PAD>INFORMATION
where
2-17
LOG
Description
The LOG command causes X29PAD to record the output of the session in
a file on disk for later reference.
Format
X29PAD>LOG (output to file) filespec
***** Log file opened at 12:34:53-EST on January 26, 1984 *****
where
filespec is the name of the file the user
wishes to use as the destination for
logging
Function
The LOG command enables the user to record a terminal session with a
REMOTE-HOST for later reference and examination. While logging is
in progress everything displayed on the users terminal (with the
exception of output generated by the user typing a question mark in
command mode) will be recorded in the file designated by the user.
The first entry in the log file will be a timestamp indicating the
date and time logging was initiated.
Notes
The way the LOG command functions is determined by certain default
conditions that may be changed by the user using the SET DEFAULT
(for) LOG command. The user may elect to have X29PAD append to
currently existing log files or to supersede existing files with a
file of a new generation. The user may also direct X29PAD to either
suppress or not suppress any null characters received from the
REMOTE-HOST. The current state of these default conditions may be
determined by using the INFORMATION (about) DEFAULTS (for) LOG
command.
Error Messages
2-18
?Could not open LOG file
2-19
PUSH
Description
The PUSH command allows the user to create a new EXEC command
process and enter it leaving X29PAD frozen intact.
Format
X29PAD>PUSH (command level)
Function
The PUSH command creates an inferior process, maps a new copy of the
EXEC into it and starts it running. X29PAD then suspends execution
until the inferior EXEC stops running (e.g. the user issues the POP
command). The user may then continue with what he was doing.
Notes
If there was a call to a REMOTE-HOST in progress when the user
issued the PUSH command, there is no guarantee that the circuit is
still intact. No notification will be given to the user if the call
is aborted due to a network error while the user is communicating
with the new EXEC. The only indication the user will receive is an
error message upon issuing the CONTINUE command.
2-20
SEND
Description
The SEND command causes a file to be read from disk and sent to the
REMOTE-HOST.
Format
X29PAD>SEND (file) filespec
where
filespec is the name of the file the user
wishes to transmit to the REMOTE-HOST
Function
The SEND command directs X29PAD to open the user specified file and
transmit it on a line by line basis to the REMOTE-HOST. When the
end of the file is reached X29PAD closes the file and reenters
command mode. While sending a file, X29PAD ignores all input from
the keyboard except for the ESCAPE-CHARACTER, the BREAK-CHARACTER,
and the STATUS-DISPLAY-CHARACTER. The user may terminate the
transmission of a file by using the ABORT command.
Notes
The SEND command does not process data read from the source file as
if it were typed by the user. Instead (for efficiency and lower
overhead) the SEND command sends data to the REMOTE-HOST on a line
by line basis. A line is defined as a character string terminated
by a carriage return.
The user may monitor the transmission by typing the
STATUS-DISPLAY-CHARACTER periodicly.
The operation of the SEND command is governed by a number of default
parameters. By using the SET DEFAULT (for) SEND command the user
may direct X29PAD to change the defaults for the SEND command.
The user may direct X29PAD's SEND command to either strip any
linefeeds immediately following carriage returns or to transmit all
linefeeds in the data stream regardless of position. The normal
action is to strip any linefeed immediately follows a carriage
2-21
return since most hosts automatically insert a linefeed after each
carriage return received.
Because of the way some REMOTE-HOST's X.29 servers are interfaced to
the system monitor, data may be lost if it is sent in large bursts.
For this reason, the user may use the SET DEFAULT (for) SEND command
to set a default time for the SEND command to pause between lines.
By setting an appropriate delay value the user can avoid overrunning
the REMOTE-HOST.
Error Messages
?A SEND is already in progress
?There is no current connection to send to
2-22
SET
Description
The SET command allows the user to set various parameters and
default modes of operation.
Format
X29PAD>SET argument-1 argument-2 ... argument-n
where
argument-1 is one of the following:
BREAK-CHARACTER DEFAULT ESCAPE-CHARACTER
NETWORK PAD-PARAMETER STATUS-DISPLAY-CHARACTER
argument-2 through argument-n are dependent on argument-1
Function
The SET command gives the user of X29PAD the ability to change
certain default operating conditions and other diverse program
parameters. There are six major variations to the SET command.
They are denoted by the second keyword in a SET command. The six
possible keywords are:
BREAK-CHARACTER DEFAULT ESCAPE-CHARACTER
NETWORK PAD-PARAMETER STATUS-DISPLAY-CHARACTER
Of these six, three of them (BREAK-CHARACTER, ESCAPE-CHARACTER, and
STATUS-DISPLAY-CHARACTER) allow the user to select (or disable) the
three interactive, single character commands. The other three
(DEFAULT, NETWORK, and PAD-PARAMETER) allow the user to change
various parameters and command defaults. These six variations of
the SET command are documented individually in the following pages.
Notes
While all SET commands may be issued while a call to a REMOTE-HOST
is in progress, care should be taken and the user should attempt to
understand the scope of any changes that are made. The user should
consult the documentation to determine if any adverse results might
occur.
2-23
SET BREAK-CHARACTER
Description
The SET BREAK-CHARACTER command allows the user to change or disable
the interactive, single character command Break.
Format
X29PAD>SET BREAK-CHARACTER argument-1 argument-2
where
argument-1 is one of the following:
the octal ASCII code for character
any printing character in double quotes
the keyword CONTROL followed by argument-2 which will be an
ASCII character in double quotes
Function
The SET BREAK-CHARACTER command allows the user to select the
character that will be recognized as an interactive request by the
user for X29PAD to perform a break sequence. When the selected
character is typed by the user during an interactive terminal
session with a REMOTE-HOST, X29PAD will perform a break sequence
whose actions are governed by the ACTION-ON-BREAK Pad Parameter (
X.3 Parameter No. 7 ) value.
The BREAK-CHARACTER may be any character whose octal value is in the
range 1 through 377.
Notes
The user may disable the interactive Break command by setting the
BREAK-CHARACTER to 0 (zero). The user may then cause a break to
occur by typing the ESCAPE-CHARACTER followed by the BREAK command.
If the BREAK-CHARACTER selected is the same as the ESCAPE-CHARACTER
the interactive break command will be disabled because X29PAD scans
typed input for the ESCAPE-CHARACTER before the BREAK-CHARACTER.
Thus, the user will escape to X29PAD's command mode and will never
2-24
reach the code to perform the interactive break.
If the BREAK-CHARACTER selected is the same as the
STATUS-DISPLAY-CHARACTER, the interactive status-display command
will be disabled since X29PAD scans typed input for the
BREAK-CHARACTER before the STATUS-DISPLAY-CHARACTER. Thus, the user
will cause X29PAD to execute a break sequence and the code to
perform the interactive status-display.
Error Messages
?Error: Argument block too long
?Error: First nonspace character is not a digit
?Error: Invalid character in number
?Error: Not a quoted string - quote missing at beginning or end
?Error: Number too large
2-25
SET DEFAULT
Description
The SET DEFAULT command allows the user to change the operational
defaults for certain X29PAD commands.
Format
X29PAD>SET DEFAULT (for) argument-1 (to) argument-2 argument-3
where
argument-1 is one of the following:
CALL LOG SEND TAKE
argument-2 and argument-3 are dependent on argument-1
Summary of SET DEFAULT Command Arguments
SET DEFAULT (for) CALL:
CLOSED-USER-GROUP string Allows you to supply a DEFAULT
CLOSED-USER-GROUP name that will be
used (unless overridden by the
CLOSED-USER-GROUP CALL subcommand) for
every call placed. (The DEFAULT for
this parameter is a null string.)
FACILITIES-DATA string Allows you to supply DEFAULT
FACILITIES-DATA that will be used
(unless overridden by the
FACILITIES-DATA CALL subcommand) for
every call placed. (The DEFAULT for
this parameter is a null string.)
USER-GROUP string Allows you to supply USER-GROUP data
that will be used (unless overridden
by the USER-GROUP CALL subcommand) for
every call placed. (The DEFAULT for
this paramerter is the string
<1><0><0><0>. Any data the user
supplies will be appended to this
string.)
2-26
SET DEFAULT (for) LOG:
APPEND Directs X29PAD's LOG command to APPEND
to the existing generation of the log
file if the file name specified by the
user already exists)
NO SUPPRESS Directs X29PAD's LOG command to
include null characters received from
the REMOTE-HOST in the log file
SUPERSEDE Directs X29PAD's LOG command to create
a new generation log file if the file
name specified by the user already
exists. (This is the DEFAULT.)
SUPPRESS Directs X29PAD's LOG command to
suppress any null characters received
from the REMOTE-HOST and not include
them in the log file. (This is the
DEFAULT.)
SET DEFAULT (for) SEND:
PAUSE n Causes the SEND command to PAUSE n
seconds between each line transmitted
to the REMOTE-HOST. (The DEFAULT
interval is 1 (one) second.)
STRIP Causes the SEND command to STRIP
linefeeds that immediately follow
carriage returns in the source file.
(This is the DEFAULT.)
TRANSMIT Causes the SEND command to TRANSMIT
all linefeeds found in the source file
to the REMOTE-HOST.
SET DEFAULT (for) TAKE:
ALLOW Causes the TAKE command to ignore any
errors that may be encountered during
the processing of a command file.
DISALLOW Causes the TAKE command to terminate
the processing of a command file if an
error is encountered. (This is the
DEFAULT.)
ECHO Causes the TAKE command to echo all
the commands in the command file being
processed.
NO ECHO Causes the TAKE command to not echo
2-27
commands being processed from the
command file. (This is the DEFAULT.)
Function
The set of SET DEFAULT commands allows the user to change certain
X29PAD command parameters. These parameters govern the actions of
their related commands. In the above summary of the SET DEFAULT
commands the initial default values are noted.
Notes
Error Messages
2-28
SET ESCAPE-CHARACTER
Description
The SET ESCAPE-CHARACTER command allows the user to change or
disable the interactive, single character command to return to
command mode.
Format
X29PAD>SET ESCAPE-CHARACTER argument-1 argument-2
where
argument-1 is one of the following:
the octal ASCII code for character
any printing character in double quotes
the keyword CONTROL followed by argument-2 which will be an
ASCII character in double quotes
Function
The SET ESCAPE-CHARACTER command allows the user to select (or
disable) the character X29PAD will interpret as an interactive
request to escape to command mode. When typed by the user, X29PAD
will figuratively place the call to the REMOTE-HOST on hold and
reenter command mode from which the user may issue commands to
modify parameters, send a file to the REMOTE-HOST, initiate or
terminate logging of the terminal session, or clear the call.
The ESCAPE-CHARACTER may be any character whose octal value is in
the range 1 through 377.
Notes
Characters typed by the user are checked to see if they are the
ESCAPE-CHARACTER before any other processing is done. If the
character typed by the user is the ESCAPE-CHARACTER then X29PAD
returns to command mode and the character is discarded. Thus, if
either the BREAK-CHARACTER or the STATUS-DISPLAY-CHARACTER (or both)
are set to the same character as the ESCAPE-CHARACTER these commands
will be effectively disabled.
2-29
It is possible to disable the interactive escape command by setting
the ESCAPE-CHARACTER to 0 (zero).
Caution
This is not recommended. There are many ways to get into a
state where there is no way to terminate the call to the
REMOTE-HOST other than by having your system manager kill
you job. There are some REMOTE-HOST X.29 servers that have
provided no way for a user to terminate the call from the
REMOTE-HOST. Therefore, it is recommended that the
interactive escape command always be enabled by having the
ESCAPE-CHARACTER set to some suitable value.
Error Messages
?Error: Argument block too long
?Error: First nonspace character is not a digit
?Error: Invalid character in number
?Error: Not a quoted string - quote missing at beginning or end
?Error: Number too large
2-30
SET NETWORK
Description
The SET NETWORK command.
Format
X29PAD>SET NETWORK
where
Function
Notes
Error Messages
2-31
SET PAD-PARAMETER
Description
The SET PAD-PARAMETER command.
Format
X29PAD>SET PAD-PARAMETER
where
argument-1 is one of the following:
ACTION-ON-BREAK CANCEL-CHARACTER
CARRIAGE-RETURN-PADDING DATA-FORWARDING
DELETE-CHARACTER DISCARD-OUTPUT
DISPLAY-CHARACTER DTE-TO-NET-FLOW-CONTROL
ECHO ESCAPE-TO-COMMAND-MODE
IDLE-TIMER LINE-WIDTH
LINEFEED-INSERTION LINEFEED-PADDING
LOCAL-EDITING NET-TO-DTE-FLOW-CONTROL
PAD-SIGNAL-CONTROL RATE
Function
Notes
Error Messages
2-32
SET STATUS-DISPLAY-CHARACTER
Description
The SET STATUS-DISPLAY-CHARACTER command allows the user to change
or disable the interactive, single character command to display call
status.
Format
X29PAD>SET STATUS-DISPLAY-CHARACTER argument-1 argument-2
where
argument-1 is one of the following:
the octal ASCII code for character
any printing character in double quotes
the keyword CONTROL followed by argument-2 which will be an
ASCII character in double quotes
Function
The SET STATUS-DISPLAY-CHARACTER command allows the user to select
(or disable) the character X29PAD will interpret as an interactive
request to display the call status. When typed by the user, X29PAD
will print a single line containing information regarding the call
status. Information provided includes the date and time, the port
state, and the number of characters and packets transmitted and
received.
The ESCAPE-CHARACTER may be any character whose octal value is in
the range 1 through 377.
Notes
The interactive status-display command may be disabled by setting
the STATUS-DISPLAY-CHARACTER to 0 (zero).
If the STATUS-DISPLAY-CHARACTER is set to the same value as either
the ESCAPE-CHARACTER or the BREAK-CHARACTER the interactive
status-display command will be effectively disabled since characters
typed by the user are checked to see if they are either the
2-33
ESCAPE-CHARACTER or the BREAK-CHARACTER before the
STATUS-DISPLAY-CHARACTER is checked for.
Error Messages
?Error: Argument block too long
?Error: First nonspace character is not a digit
?Error: Invalid character in number
?Error: Not a quoted string - quote missing at beginning or end
?Error: Number too large
2-34
TAKE
Function
The TAKE command.
Format
X29PAD>TAKE (commands from) filespec
where
2-35
CHAPTER 3
USING X29PAD
3-1
APPENDIX A
SAMPLE TERMINAL SESSION
The following is a sample of an X29PAD terminal session. All user input is
in BOLD print.
@x29pad
This is X29PAD version 2(300)
Gateway Access Library version is 1(0)
X29PAD>set network name telenet
X29PAD>set network password frobaz
X29PAD>set break-character control "\"
X29PAD>set escape-character control "P"
X29PAD>call 234211111111 0
BREAK-CHARACTER (is) CONTROL-\
ESCAPE-CHARACTER (is) CONTROL-P
Calling Remote DTE 234211111111 (0) [FAILED]
?Call not completed - Remote DTE number is out of order
Network clear code 9, diagnostic code 0
Call cleared at 13:10:08-EDT on May 18, 1983
Transmitted 0 characters in 0 packets.
Received 0 characters in 0 packets.
X29PAD>call black-and-blue
BREAK-CHARACTER (is) CONTROL-\
ESCAPE-CHARACTER (is) CONTROL-P
Calling Remote DTE 208006088888 [OK]
This is the Headquarters VAX 11/750, node _BLACK::
Username: derek
Password:
$ ^P
X29PAD>information (about) pad-parameters
Current PAD Parameters are:
*ACTION-ON-BREAK (is) NOTHING
*CANCEL-CHARACTER (is) CONTROL-@
CARRIAGE-RETURN-PADDING (is) DISABLED
*DATA FORWARDING (is done on) CARRIAGE-RETURN
CONTROL-CHARACTERS
EDITING-CHARACTERS
ESCAPE-CHARACTERS
TERMINATOR-CHARACTERS
A-1
*DELETE-CHARACTER (is) A RUBOUT
*DISCARD-OUTPUT (is) DISABLED
*DISPLAY-CHARACTER CONTROL-@
*DTE-TO-NET-FLOW-CONTROL (is) ENABLED
*ECHO (is) DONE LOCALLY
ESCAPE-TO-COMMAND-MODE (is) PERMITTED
*IDLE-TIMER (is) DISABLED
LINE-WIDTH (is) 0
*LINEFEED-INSERTION (is done after) NO CARRIAGE-RETURNS
LINEFEED-PADDING (is) DISABLED
*LOCAL-EDITING (is) ENABLED
*NET-TO-DTE-FLOW-CONTROL (is) DISABLED
PAD-SIGNAL-CONTROL (is) ENABLED
RATE (is) 300 BAUD
( * Indicates PAD Parameters which were set by the remote host )
X29PAD>continue (current call)
$ show us
VAX/VMS Interactive Users - Total = 11
18-MAY-1983 18:12:52.50
NVA20: DEREK 002D0037
RTA1: DIXON 00120036
RTA2: X25MASTER 00520038
TTA3: NIISATO 00230031
TTB0: COBB 00440032
TTB5: HUNT 0061003A
TTC0: STAW 00B90043
TTC1: BRYSON 002A0030
TTC2: NEWLAND 00010018
TTC7: NIISATO 00150034
TTF0: PATEL 0066003E
$ logout
DEREK logged out at 18-MAY-1983 18:12:59.04
^P
X29PAD>exit
Call cleared at 13:12:04-EDT on May 18, 1983
Transmitted 46 characters in 6 packets.
Received 1146 characters in 36 packets.
@
A-2
APPENDIX B
X.3 PAD PARAMETERS
The following is a list of the CCITT X.3 PAD Parameters along with their
meaning and possible values. X29PAD does not use all of these currently.
Those parameters not used by X29PAD are flagged with star (*).
PLEASE NOTE: The user should not attempt to set individual PAD Parameters.
X29PAD initializes them each time it tries to place a call to a remote host
and the remote host then will set them to a known state. Setting PAD
Parameters in the middle of a terminal session with a remote host can
produce unpredictable (and undesireable) results.
Parameter Description
Number
1. Escape to Command Mode (*). This parameter has two possible values
- ALLOWED or DISALLOWED. X29PAD ignores this parameter and always
allows the user to return to command mode by typing the
ESCAPE-CHARACTER.
2. Echo. This parameter determines whether X29PAD should do the
echoing of characters or the remote host will do the echoing. This
parameter has two possible values - LOCAL or REMOTE.
3. Data Forwarding. This parameter describes the set of characters
that, when typed by the user, will cause X29PAD to transmit
whatever data is in the input buffer. This parameter has the
following possible values:
1. No data forwarding character specified (disabled).
2. Alphanumerics (A-Z, a-z, 0-9)
3. Carriage Return
4. Escape Characters (ESC, BEL, ENQ, ACK)
B-1
5. Editing Characters (DEL, CAN, DC2)
6. Terminator Characters (ETX, EOT)
7. Forms Control Characters (HT, LF, VT, FF)
8. All Other Control Characters
Only the following combinations of the above are legal:
1. (1)
2. (3)
3. (3 and 4)
4. (3 and 6)
5. (3, 4, 5, 6, 7, and 8) - DEFAULT
4. Idle Timer. This parameter controls the frequency that X29PAD will
forward data in the input buffer to the remote host. The timer may
either be DISABLED or be set to an interval from 0.05 seconds to
12.75 seconds in 0.05 second increments. The Idle Timer is
DISABLED by default.
5. DTE to Network Flow Control (*). This parameter determines whether
X29PAD can use XON/XOFF to control data flow from the terminal.
X29PAD does not currently use this parameter.
6. PAD Service Signal Suppression (*). This parameter determines if
X29PAD will suppress service signals. X29PAD ignores this
parameter.
7. Action on Break. This parameter specifies the action X29PAD takes
when the user types the BREAK-CHARACTER on the terminal. The
possible values are:
1. No action
2. X29PAD sends an interrupt to the remote DTE
3. X29PAD sends a reset to the remote DTE
4. X29PAD sends an Indication Break message to the remote DTE
5. X29PAD enters command mode
6. X29PAD discards output to the terminal (Parameter 8 set to 1)
7. Combination of 2, 4, and 6
The default value for this parameter is RESET.
B-2
8. Discard Output. This parameter determines if X29PAD will display
data from the remote host on the user's terminal or discard it.
9. Carriage Return Padding (*). This parameter controls the number of
nulls X29PAD should send after it sends a carriage return to the
terminal. X29PAD currently ignores this parameter.
10. Line Width (*). This parameter is the width of the users terminal.
X29PAD currently ignores this parameter.
11. Rate (*). This parameter contains the speed of the users terminal.
X29PAD currently ignores this parameter.
12. Network to DTE Flow Control (*). This parameter determines whether
or not the user's terminal can control the data flow from the local
host system. X29PAD currently ignores this parameter.
13. Linefeed Insertion after Carriage Return. This parameter
determines if and when X29PAD will insert a linefeed after a
carriage return in the data stream. This parameter has the
following values:
1. Never insert a linefeed after a carriage return.
2. Insert a linefeed after carriage returns sent to the terminal.
3. Insert a linefeed after carriage returns sent to the remote
host.
4. Insert a linefeed after carriage returns X29PAD echos.
5. All combinations of 2, 3, and 4.
The default for this parameter is to never insert a linefeed.
14. Linefeed Padding (*). This parameter controls the number of nulls
to be inserted into the data stream after a linefeed. X29PAD does
not use this parameter.
15. Local Editing. This parameter controls the local editing feature
of X29PAD. This parameter has two possible values. If local
editing is ENABLED, X29PAD will allow the user to edit any text in
the input buffer before it is passed on to the remote host. If
local editing is DISABLED, X29PAD will not allow local editing to
be done. Note that parameters 16, 17, and 18 are ignored by X29PAD
if local editing is disabled.
16. Delete Character. This parameter specifies the character for
deleting characters in the editing buffer while in data transfer
state. The possible values are DISABLED (value of 0) or an ASCII
character. The default setting for this parameter is RUBOUT. This
parameter is ignored if LOCAL-EDITING is disabled.
17. Cancel Character. This parameter specifies the line delete
character for deleting lines in the editing buffer. The possible
values are DISABLED (value of 0) or an ASCII character. The
default setting for this parameter is CONTROL-U. This parameter is
B-3
ignored if LOCAL-EDITING is disabled.
18. Display Character. This parameter specifies the line display
character for editing while in the data transfer state. The
possible values are DISABLED (value of 0) or an ASCII character.
The default setting for this parameter is CONTROL-R. This
parameter is ignored if LOCAL-EDITING is disabled.
B-4
APPENDIX C
FACILITIES DATA
C-1
APPENDIX D
GLOSSARY
Bilateral Closed User Group (BCUG)
An optional PPSN facility that restricts a pair of DTEs to
communicating with each other. The basic BCUG also prevents this
pair from accessing or being accessed by other DTEs. Additions to
the BCUG facility allow one or both of the DTEs to access or be
accessed by DTEs outside the group. These additions are known as
BCUG with Outgoing Access and BCUG with Incoming Access
respectively.
CCITT
Comite Consultatif International Telegraphique et Telephonique. An
international advisory committee that sets international
communications usage standards.
Channel
A logical path between a DTE and a DCE over which data is
transmitted. Each channel is identified by a unique reference
number called a Logical Channel Number (LCN).
Character Mode DTE
A DTE that is unable to handle data in packet form. This DTE must
interface through a Packet Assembly/Disassembly (PAD) facility to
connect to a PPSN. Also known as a Remote X.29 Terminal.
Closed User Group (CUG)
An optional PPSN facility that restricts two or more DTEs in the
same group to communicating with each other. The basic CUG also
prevents these DTEs from accessing or being accessed by other DTEs
outside the group. Additions to the basic CUG facility allow one or
more DTEs to access or be accessed by DTEs outside the group. These
additions are known as CUG with Outgoing Access and CUG with
Incoming Access respectively.
Data Circuit-terminating Equipment (DCE)
D-1
A CCITT X.25 term referring to the network equipment that provides
functions to establish, maintain and terminate a connection and
handle the signal conversion and coding between the data terminal
equipment and the network. The switching exchange of the network to
which DTEs are connected. (In non-X.25 usage, the term is
synonymous with 'modem'.)
Data Terminal Equipment (DTE)
A CCITT term referring to the user's equipment (computer or
terminal) connected to a DCE on a packet switching network for the
purpose of sending and/or receiving data.
DCE
See Data Circuit-terminating Equipment.
DECnet
The collective name for the software and hardware products that
allow various DIGITAL operating systems to be interconnected to form
computer networks. A network is a configuration of two or more
independent computer systems linked together to share resources
and/or exchange information.
DTE
See Data Terminal Equipment.
Duplex
Simultaneous two-way independent transmission in both directions.
Also referred to as full-duplex.
Facility
A service or mode of operating that a PPSN is able to provide for a
user upon subscription and/or request, for example, fast select or
reverse charging.
Fast Select
An optional PPSN facility that allows a DTE to include a user data
field of up to 128 bytes when setting up a virtual circuit.
Flag Sequence
A series of ones and zeros that indicate the start and end of a
frame.
Flow Control
The mechanism which ensures that the sending station does not
overrun the receiving station with more packets that it can accept.
Flow Control Parameter Negotiation
D-2
A process that permits selection of packet sizes and window sizes in
each direction of a particular virtual circuit.
Frame
A unit delimited by flags that includes a header, used by the link
level to exchange packets as well as control and error information
between the DTE and the DCE.
Full-Duplex
See Duplex.
Gateway
The connection between two individual packet switching networks.
The connection provides a link through which a DTE can communicate
with a DTE on a different network. A gateway is covered in CCITT
Recommendation X.75.
Half-Duplex
A circuit designed for transmission in either direction but not both
directions simultaneously.
Header
The control information before a message text; for example, source
or destination code, priority, or packet or frame identification.
Incoming Calls Barred
An optional PPSN facility that prevents a DTE from accepting any
calls.
Local DTE
A frame of reference; the DTE at which the user is located.
Logical Channel
A logical link between a DTE and its DCE. The physical
communications line between a DTE and DCE is divided into a set of
logical channels.
Logical Channel Number (LCN)
A unique reference number that identifies a logical channel. A DTE
recognizes a virtual circuit by its associated LCN.
Message
A communication, prepared for information interchange in a form
suitable for passage through the interchange medium. It includes:
o All portions of the communications such as machine sensible
controls o An indication of the start of the message and the end of
the message o A header containing routing and other information, one
D-3
or more texts containing the originator-to-addressee
communication(s), and the end of text indicator In packet switching,
a message may be segmented into several packets to traverse the
network, or in some circumstances several messages can be carried in
one packet.
Modem (Modulator-Demodulator)
A device that translates digital signals (electrical impulses)
generated by a computer into analogue signals (tones) that can be
transmitted over telephone lines, and vice versa.
Non-packet-mode DTE
See Character Mode DTE.
Non-standard Default Packet Size
An optional PPSN facility that permits a DTE to specify a default
packetsize that is different from the PPSN's default.
Non-standard Default Window Size
An optional PPSN facility that permits a DTE to specify a default
windowsize that is different from the PPSN's default.
Octet
A group of eight bits; a byte.
One-way Logical Channel Incoming
An optional PPSN facility that prevents a particular logical channel
from handling outgoing calls.
One-way Logical Channel Outgoing
An optional PPSN facility that prevents a particular logical channel
from handling incoming calls.
Outgoing Calls Barred
An optional PPSN facility that prevents a DTE from initiating any
calls.
Packet
The unit of data switched through a PPSN; normally a user data
field accompanied by a header carrying destination and other
information.
Packet Assembly/Disassembly (PAD) Facility
A device at a PPSN node that allows access from an asynchronous
terminal, such as an LA36. The terminal connects to the PAD and the
PAD puts the terminal's input data into packets (assembles) and
takes the terminal's output data out of packets (disassembles).
D-4
Packet Control
The functions concerned with the correct routing and reception of
individual packets through the network.
Packet-mode DTE
A DTE that can handle data in packet form. This implies a
capability for assembling and disassembling packets. A computer is
one type of packet-mode DTE.
Packet Receive Sequence Number (P(R))
The P(R) number indicates that all packets up that number minus one
have been received. The P(R) number thus authorizes the
transmission of further packets by updating the lower window edge.
Packet Send Sequence Number (P(S))
The P(S) number specifies the position of a packet in a sequential
stream. The number starts at zero for the first packet and
increases by one for each successive packet sent on one logical
channel in one direction. The P(S) number may be either modulo 8 or
modulo 128 although modulo 8 is the default for all PPSNs. A packet
can only be transmitted if its P(S) is greater than or equal to the
lower window edge and less than the upper window edge.
Packet Switching
A data transmission process, utilizing addressed packets, whereby a
channel is occupied only for the duration of transmission of the
packet.
NOTE
In certain data communication networks, the data may be
formatted into a packet or divided and then formatted into a
number of packets (either by the data terminal equipment or
by equipment within the network) for transmission and
multiplexing purposes.
Packetnet System Interface (PSI)
The collective name for the hardware and software products that
allow various DIGITAL operating systems to participate in a packet
switching environment.
Permanent Virtual Circuit (PVC)
A permanent logical association between two DTEs, which is analogous
to a leased line. Transmission of packets on a PVC needs no call
set up or call clearing by the DTE. Packets are routed directly by
D-5
the network from one DTE to the other.
Port
A collection of resources that maintain a virtual circuit.
PPSN
See Public Packet Switching Network.
Protocol
An agreed set of rules governing the operation of a communications
link.
Public Packet Switching Network (PPSN)
A set of equipment and interconnecting links that provides a packet
switching communications service to subscribers within a particular
country.
PVC
See Permanent Virtual Circuit.
Qualified Data
Data transmitted in a packet in which the Qualifier bit is set.
This bit is usually reserved for special applications, such as
higher level protocols. For example, X.29 protocol messages are
transmitted between PADs as qualified data messages.
Remote DTE
A frame of reference: any DTE in a network other than the one at
which the user is located.
Remote Virtual Terminal
A terminal connected to a Packet Assembly/Disassembly (PAD)
facility.
Reset
A reset allows a DTE to re-initialize a virtual circuit by resetting
the lower window edge and P(S) and P(R) numbers to zero. All Data
and Interrupt packets that may be in the network are discarded.
Reverse Charging
An optional PPSN facility that allows a DTE to request that the
remote DTE is charged for a particular call.
Start Element
A single 0-bit that marks the start of a character in start-stop
transmission.
D-6
Start/stop Transmission
Asynchronous transmission in which a group of bits corresponding to
a character is preceded by a start element and is followed by a stop
element.
Stop Element
Either one or two 1-bits that mark(s) the end of a character in
start-stop transmission.
SVC
See Switched Virtual Circuit.
Switched Virtual Circuit (SVC)
A temporary logical association between two DTEs connected to a PPSN
which is analogous to connection by a dial-up line. An SVC is set
up only when there is data to transmit and is cleared when the data
transfer is complete.
Tariff
A published rate for telecommunications services.
Throughput Class Negotiation
An optional PPSN facility that indicates the maximum data rate for a
particular virtual circuit. The facility allows a DTE to request a
higher or lower data rate depending on the throughput of the
packets.
Virtual Circuit
An association between two DTEs connected to a PPSN whereby the two
DTEs are able to interact as if a specific circuit were dedicated to
them throughout the transmission. In reality, a logical connection
is established, and the actual physical circuits are allocated
according to route availability, overload conditions, and so on.
Window
At the DTE/DCE interface of the logical channel used for an SVC or
PVC and for each direction of transmission, a window is defined as
the ordered set of consecutive data packets authorized to cross the
interface. The lowest sequence number in the window is called the
lower window edge. When an SVC or PVC at the DTE/DCE interface has
just been established, the window related to each direction of data
transmission has a lower window edge equal to 0. The packet send
sequence number of the first data packet not authorized to cross the
interface is the value of the upper window edge; that is, the lower
window edge plus the windowsize.
X.3
A CCITT recommendation that specifies the Packet
D-7
Assembly/Disassembly (PAD) facility in a public data network.
X.25
A CCITT recommendation that specifies the interface between Data
Terminal Equipment and Data Circuit-terminating Equipment for
equipment operating in the packet mode on public data networks.
X.28
A CCITT recommendation that specifies the DTE/DCE interface for a
start-stop mode DTE accessing the Packet Assembly/Disassembly (PAD)
facility in a public data network situated in the same country.
X.29
A CCITT recommendation that specifies procedures for the exchange of
control information and user data between a packet-mode DTE and a
Packet Assembly/Disassembly (PAD) facility.
X.75
The CCITT recommendation that specifies the procedures for
communicating between PPSNs.
D-8
Index
D-9
Reader's Comments
D-10