This is pretty interesting to me, because in the past I've noticed that
when I connect to TSO via a 3270 control unit (let's call that port
3270) such as on the Hercules TK4 setup, Vista TN3270 Attention doesn't
work as expected - X-SYSTEM appears but nothing else happens. But
Attention DOES work when I connect to a z/OS system via TCPIP/TN3270
(let's call that port 23).
Now with PCOMM, Attention works fine via TCPIP port 23, and *also* works
fine via a control unit port 3270 So what's up with that? I took some
WireShark traces just now and here are the bytes that flew by:
Key Vista PCOMM
------- ------- -----------
PA1 6CFFEF 6CFFEF same
PA2 6EFFEF 6EFFEF same
Attn FFF3 6CFFEF FFF3 different!
So if you ask me, PCOMM (very old version on my PC by the way) is
sending *both* a PA1 and Attention sequence to the TN3270 server. Since
(externally) that seems to act exactly like PA1 when it arrives, all I
can guess is the FFF3 is being ignored. That actually works better on a
3270 port because it causes the action I want and doesn't lock up the
screen.
Notes: For this test I used the PCOMM keypad pulldown which I assume has
never been altered by me over the years I've had the program. 6C and 6E
are AID (attention identifier) bytes. AID codes are passed to the host
when you press a key such as Enter, Clear, PF keys, and of course
PA1/PA2/Attn. The FFEF marks the end of a TN3270 data block, so we can
ignore that. Any FFxx code is picked up by the TN3270 server (never
sent to VTAM in that form), and in this case supposed to do whatever
logic is needed to tell VTAM an attention was issued. PCOMM may have
options to alter its Attention processing - I know there are a whole lot
of INI options in that program. If I touched something there, I've long
since forgotten.
On 2/19/2019 3:50 PM, Farley, Peter x23353 wrote:
Experiment showed me that both PCOMM and Vista TN3270 seem to send the same thing for "Attention",
as both emulators work using "Attention" as "reshow" on my employer's network.
Unfortunately there is no chance I could arrange to get a buffer trace from my employer's mainframe
communications team when we have no problem.
I'm not sure what intermediary system(s) my friend uses there. I can ask, but my friend
was quite happy to learn about using PA1 / PA2 for "reshow", so it may be a
moot point.
Thanks to all for your replies to satisfy my curiosity. I love learning like
this, in a community that cares enough to educate and inform.
Peter
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf
Of Seymour J Metz
Sent: Tuesday, February 19, 2019 6:17 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: Where does ISPF determine how to repsond to "Attention" function?
ISPF uses VTIOC facilities, e.g., TGET, TPG, TPUT, to communicate with the
terminal. By default VTIOC will interpret ATTN or PA1 as attention and PA2 as
reshow. However,
1. It's anybody's guess whether PCOMM send ATTN or PA1 for "Attention".
2. ISPF runs in full screen mode, so things are a little different.
3. The above assumes that VTIOC is in session with the terminal, not with an
intermediate program.
From what you wrote I would assume that at your friend's shop the terminal is
coming in through, e.g., NVAS, TPX.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
________________________________________
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of Farley,
Peter x23353 <peter.far...@broadridge.com>
Sent: Monday, February 18, 2019 5:20 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Where does ISPF determine how to repsond to "Attention" function?
[Dual-posted to ISPF-L and IBM-MAIN]
On my employer's z/OS 2.2 system and as far back as they have employed me (OS/390 R10 IIRC), pressing
"Attention" (Esc on my PCOMM keyboard map) while in an ISPF screen "refreshes" the screen
to the last stable state, so if you accidentally erased a whole line of program code or JCL you can recover
what was there before the erase as long as you didn't press Enter or any PF/PA key before pressing
"Attention".
On a friend's z/OS system (not sure of the release), pressing "Attention" at
any ISPF screen causes the terminal to be taken out of service (VTAM INACT).
My question is where and how does ISPF determine how to respond to "Attention"
to refresh the screen instead of making the terminal INACT? Or is that a VTAM
function/setting of some kind? If it is VTAM, where is it specified?
Just curious here, no actual problem to be solved ("Doctor! Doctor! It hurts when I do
that!"; "Well, don't do that!").
Peter
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