Tony Non-SNA 3270 is full-duplex so regular AID-generating keys[1] may be used at any time, including PA1.
SNA 3270 is half-duplex so regular AID-generating keys may *not* be used at any time. Specifically an AID-generating key may not be used when TSO as the primary LU application possesses the "direction baton". The special protocol which "asks for" the "direction baton" to be transferred is needed. This is what the Attn key does; it sends a SIGNAL request unit. As well as passing the "direction baton" in the following - answering - outbound request unit, TSO treats the SIGNAL as a TSO attention condition. You gave the real explanation for Paul's frustration in an earlier post. That TSO attention condition needs to be "seen" by whatever is application or sub-application running. I used to make students aware of the TSO attention condition under various circumstances - whether the session was LU 2, "SNA", or LU 0, "non-SNA", for example - but my "long-running" program was TSO spewing out HELP text. Saying that I then remembered I used to have something better. I checked my X.25 class exercise document and rediscovered that I had a "lock" command which just freezes the TSO conversation until, this being an X.25 PAD exercise, the asynchronous ASCII device "break" key is used. Unfortunately I can't remember exactly what this clever program consisted of. Maybe it was simply a program which waited for the TSO attention condition to arise which would have meant that I was using the TSO command API. [1] Enter, a PF key, a PA key, Clear - and more obscure clever things like one of the light pen options - not to have to go digging in the manual. Chris Mason ----- Original Message ----- From: "Tony Harminc" <[EMAIL PROTECTED]> Newsgroups: bit.listserv.ibm-main To: <IBM-MAIN@BAMA.UA.EDU> Sent: Friday, 12 January, 2007 5:48 PM Subject: Re: Interrupting DSLIST [resent with the correct Reply To] > ... > > When we say "ATTN", it can mean either the SNA 3270 ATTN function, or the > TSO ATTN function. Generally the former is presented to a TSO application as > the latter, but 3270 "PA1" is also presented as TSO ATTN if the keyboard is > logically unlocked. > > Tony H. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
