HPlogo System Debug Reference Manual: HP 3000 MPE/iX Computer Systems > Chapter 4 System Debug Command Specifications

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Privileged Mode

Adds/deletes/lists terminals used for demonstrating System Debug.

Syntax

   DEMO 

   DEMO LIST 

   DEMO ADD    ldevs

   DEMO DELETE ldevs

The DEMO command is used for giving demonstrations of System Debug. With this command, the user is able to enslave up to 50 terminals. Each of the enslaved terminals receives all input and output generated by System Debug. Output generated by the CI through the use of the ":" command or CIGETVAR and CIPUTVAR functions is not sent to the enslaved terminals.

Please read and heed the warnings listed in "Limitations, Restrictions."

Parameters

DEMO

List the terminal LDEV's that currently are receiving System Debug I/O.

DEMO LIST

Both command forms are identically supported.

DEMO ADD

This keyword tells System Debug to add the following LDEVs to the list of terminals to receive a copy of all System Debug I/O.

DEMO DELETE

This keyword tells System Debug to remove the following LDEVs from the list of terminals that receive a copy of all System Debug I/O.

ldevs

A list of terminal LDEV numbers (logical device numbers), separated by blanks or commas. A note of caution: remember that the LDEV numbers are interpreted using the current input base for System Debug.

Examples

   $nmdat > demo

   No demonstration terminals are defined



   $nmdat > demo add #200 #201 #205 #206



   $nmdat > demo list

   DEMO LDEVS (#): 200 201 205 206

First, check to see if any demonstration LDEVs have been specified. Next, add four LDEVs to the list of terminals to receive a copy of DAT's input and output stream. As soon as the DEMO ADD command is processed, the indicated terminals begin receiving I/O. Finally, display the list of demonstration terminals.

Limitations, Restrictions

A total of 50 demonstration LDEVs are supported.

The functionality is implemented with low-level I/O routines. I/O is done directly to the LDEV. No attempt is made to lock or obtain ownership of the LDEV before sending data to it. Nonpreemptive I/O is used when sending data to the LDEVs. Therefore, if a read is pending at the LDEV (For example, the CI prompt), System Debug blocks until the pending read is satisfied. It is good practice to free up the LDEVs that will be used during a demonstration by issuing the :RESTORE command at each terminal (do not REPLY to the resulting tape request). This removes any pending I/O from the LDEV. When the demonstration is finished, break out of the RESTORE process and issue an ABORT command.

No validation of LDEV numbers is performed. If you give an ldev, then no matter what the value is, System Debug tries to write to it!

The same LDEV may be specified more than once, in which case the LDEV is sent a copy of any I/O for each occurrence in the list of LDEVs.

The Control-S/Control-Q/stop keys suspend output only for the master terminal (that is, the one where the demonstration is being run). All of the enslaved terminals continue to receive output as an uninterrupted flow.

CAUTION: The output format of all System Debug commands is subject to change without notice. Programs that are developed to postprocess System Debug output should not depend on the exact format (spacing, alignment, number of lines, uppercase or lowercase, or spelling) of any System Debug command output.


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