TOPS-20 Commands Reference Manual

SET HOST

Connects your terminal to another system.

Format 1

@SET HOST node-name::  /switch

Format 2

(Omitting the node name on the command line allows you to define an interrupt sequence)

@SET HOST /switch
Two character interrupt sequence (^\,<RET>): interrupt-sequence
Node name: node-name::

where:

node-name:: is the name of the remote host that you want to connect your terminal to. Two colons (::) following the node name are optional.
/switch is an optional keyword that selects the service used to connect your terminal to a remote node.

Default - /CTERM

interrupt-sequence is the characters that switch control of the terminal back to the local host. You are prompted for an interrupt sequence only if you give the /CTERM switch.

Default - CTRL\,<RET>

NOTE
This command description assumes you are connecting to another TOPS-20 system. For information on accessing other operating systems, see the DIGITAL Networking Pocket Guide. This command description also assumes that you are establishing a connection with the CTERM program.
SET HOST Command Switches
/CTERM connects your terminal to the remote node by running the CTERM communications program. Both processors must be running DECnet Phase 4 software (available under a separate license). The SET HOST command runs the CTERM communications program by default. If the remote node does not support the CTERM protocol, SET HOST attempts the connection again. In the second attempt however, SET HOST runs the communications program defined by the logical name NRT: (Network Remote Terminal).

Default

/NRT runs the communications service program defined by the logical name NRT: (Network Remote Terminal). NRT: can be a system or job logical name. When both exist, the job definition takes precedence.

Characteristics

Logging into the Remote Node

Once your terminal is connected to the remote node, the system responds by identifying itself and prompting you to log in. You can then log in to the system.

Path of Terminal Input and Output

The SET HOST command passes terminal input through the local host to the remote host. Output from the remote host passes through the local host to your terminal.

Making a Series of Host Connections

Once you have logged in to a remote node, you can give EXEC commands and run programs just as you would on your local node. You can then establish a connection to another remote node. For example, if your local host is AURORA, you can give the command SET HOST BOSTON to connect to the node BOSTON; after logging in to BOSTON, you can use the command SET HOST DENVER to connect to node DENVER.

Returning to Your Local Host

To return your terminal to your local host, type the interrupt sequence to temporarily break the connection to the remote host. Note that the connection to the remote host remains intact until you reset the CTERM program. You can reconnect your terminal to the remote host by giving the CONTINUE command.

When you log out of the remote host, the connection is broken and you are returned to your local host.

If you have established a series of connections, the interrupt character defined in your first SET HOST command returns you to your local host. For example, your local host is AURORA and you SET HOST to BOSTON, specifying the CTRL\<RET> interrupt sequence to return to AURORA. Then from BOSTON you connect to DENVER. Typing the CTRL\<RET> interrupt to DENVER returns you to AURORA, not BOSTON.

Specifying the Interrupt Sequence
Controlling Scrolling on a Remote Host

On your local host, <CTRL/S> and <CTRL/Q> are the default control characters that pause and continue scrolling. Typing <CTRL/Q> continues scrolling whether scrolling paused because you typed <CTRL/S> or the output paused on an end-of-page.

However, CTERM does not pass these characters to the remote host. When using <CTRL/S> and <CTRL/Q>, it is the local host that actually controls scrolling. Therefore if output from the remote host has paused on an end-of-page, <CTRL/Q> will not continue scrolling. Other pause and continue characters are passed to the remote host. You can use <CTRL/A> to both pause and resume scrolling or you can use the TERMINAL PAUSE command to assign any two characters of your choosing to control scrolling. For consistency, it is recommended that you define the same pause and continue characters on your local and remote node.

Hints

Listing Available Nodes

Use the INFORMATION DECNET command to display the names of DECnet nodes accessible to your node.

Effect on Terminal

The SET HOST command connects your terminal to the remote system. After the remote system's herald message is printed, you can log in.

Related Commands

CONTINUE for resuming a connection that was broken with an escape sequence.
INFORMATION DECNET for displaying the names of nodes reachable from your node.
INFORMATION JOB-STATUS for displaying the name of the host node and other information about your job.
INFORMATION LOGICAL-NAMES NRT: for displaying the name of the communications program run by /NRT.
SYSTAT for displaying (in the ORIGIN column) the name of the local system (the system you connected to before connecting to the current remote system).

Examples

  1. Connect your terminal to a remote TOPS-20 node named AURORA and then login.
    @SET HOST AURORA
    
    [Attempting a connection, connect OK, ]
    [Remote host is a TOPS-20 system]
    [TYPE ^\,<RET> to return to node ROMAX]
    
     AURORA - Claims Tracking System, TOPS-20 Monitor 7(21002)
    @LOGIN RSMITH
     Job 4 on TTY315 15-Nov-87 09:35:03, Last Login 15-Nov-87 08:18:48
    
  2. Give the INFORMATION DECNET command to find out if node BOSTON is reachable from your host node. Then give the SET HOST command without typing the node name on the command line. Omitting the node name causes the system to prompt you for an interrupt sequence. After typing your own interrupt sequence, the system prompts you for the name of the remote node.
    @INFORMATION DECNET BOSTON
     Node BOSTON is reachable
    @SET HOST
    Two character interrupt sequence (^\,<RET>): ^ED
    Node name: BOSTON
    
    [Attempting a connection, connect OK, ]
    [Remote host is a TOPS-20 system]
    [TYPE ^E,D to return to node AURORA]
    
     BOSTON, AI Engineering Center, TOPS-20 Monitor 7(21002)
    @
    
  3. Connect to a remote node named TEAL. After logging in and doing some work on TEAL, type the ^\<RET> interrupt sequence to return to your local host.
    @SET HOST TEAL
    
    [Attempting a connection, connect OK, ]
    [Remote host is a TOPS-20 system]
    [TYPE ^\,<RET> to return to node FLYWAY]
    
     TEAL - Migratory Bird Banding, TOPS-20 Monitor 7(21002)
    @LOGIN LOWELL
     Job 4 on TTY315 15-Nov-87 09:35:03, Last Login 15-Nov-87 08:18:48
        .
        .
    ^\<RET> (Interrupt sequence not displayed on terminal)
    [Connection interrupted, back at node FLYWAY,
    Type CONTINUE to resume connection]
    

    After working on node FLYWAY, type the CONTINUE command to reconnect your terminal to node TEAL. Then give the INFORMATION JOB-STATUS command to verify that you are connected to TEAL.

    @CONTINUE
    
    @INFORMATION JOB-STATUS
     Host TEAL
     Job 17, TTY4, User LOWELL, REPORTS:<LOWELL>
     Account 341
    
  4. Attempt a connection using the CTERM program. The system attempts the connection and finds that the remote node does not support CTERM. It then attempts another connection using the program defined by NRT:
    @SET HOST ROMAX
    
    [Attempting a connection, Connect failed -
    
     Host did not accept CTERM connection, trying NRT:
    
    
    [Attempting a connection, connect OK]
    [Remote host is a TOPS-20 system]
    [TYPE ^P to return to node AURORA]
    
     ROMAX - Acme's Timesharing System, TOPS-20 Monitor 7(21002)
    @