From: utzoo!decvax!ucbvax!info-vax
Newsgroups: fa.info-vax
Title: Re: Reply to many things
Article-I.D.: ucbvax.104
Posted: Fri Mar 25 13:06:56 1983
Received: Sat Mar 26 09:18:17 1983

>From GEOFF5@SRI-CSL  Fri Mar 25 11:13:05 1983
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To: Hobbit <AWalker@RUTGERS>
Cc: Info-VAX@SRI-CSL
Barefoot: Always, too
In-Reply-To: Hobbit's message of Wed, 23 Mar 83 02:26 EST
Via:  rice; 24 Mar 83 0:10-CDT
Via:  Rice; 24 Mar 83 0:14-PDT
Remailed-Date: 24 Mar 1983 1830-PST
Remailed-From: the tty of Geoffrey S. Goodfellow  <Geoff5 at SRI-CSL>
Remailed-To: Info-VAX@SRI-CSL.ARPA: ;

I tried replying to this before, but I don't think my message ever
got through.  Anyway, the problem you have been having with BRDCST and
type-ahead on terminals is really quite simple.  There is a bit (yes,
it is NOT shown by 'show terminal') that controls whether messages are
sent to this mailbox when unsolicited input is typed on the terminal.
Below are a few relevent sections from the VMS I/O Users Guide (Volume 1):

----------------------------------------

9.2.5 Terminal/Mailbox Interaction

...
Messages are sent to mailboxes under the following conditions:

    o  Unsolicited data in the type-ahead buffer.  The use of the
       associated mailbox can be enabled and disabled as a
       subfunction of the read and write requests...
       The default on all terminals is enabled.
...

----------------------------------------

Table 9-8:  Read QIO Function Modifiers

...
IO$M_DSABLMBX           The mailbox is disabled for unsolicited data.
...

----------------------------------------

Table 9-9:  Write QIO Function Modifiers

...
IO$M_ENABLMBX           Enables use of the mailbox associated with the
                        terminal for notification that unsolicited data
                        is available.
...

----------------------------------------

I haven't seen a copy of BRDCST, but what it should do is either ignore
all unsolicited input messages, or, preferably, disable the use of the
mailbox for this purpose.  One way to do this would be to do a timed read
for 0 seconds of 0 characters from the terminal with the IO$M_DSABLMBX
modifier (you have to do a read to use this modifier).  The read will
act as a no-op, but will prevent further unsolicited data messages from
being sent into this mailbox.

                                        Dave Johnson
                                        Dept. of Math Science
                                        Rice University