On Wed, Nov 02, 2022 at 09:23:59AM -0400, Brian Chapman wrote: > I was following his coding example for checking if the terminal accepts a > Query, but I mistakenly overlooked the fact that this is only for TSO. I > planned to add the GTTERM early in the process of establishing the VTAM > terminal to determine if Read Partition - Query is acceptable. For a VTAM > application, is it safe to assume that all connecting terminals accept Read > Partition - Query?
In my mind, it's not "correct" to assume that all 3270s accept Read Partition Query, however it might be that today (as opposed to the decades ago when I was doing this). On the other hand, there still might be some TCP/IP connected 3270 simulator programs which don't support Read Partition Query. You haven't shown any VTAM code, but there should be some part of the original VTAM session establishment which provides information on the other end of the VTAM session to be. In addition to checking that the LU (VTAM logical unit) connecting is some sort of 3270, there is somewhere a bit which says if it supports Read Partition Query. This information about the device at a minimum includes the primary and secondary screen sizes, as well as a bit about Read Partition Query support. You've seen the following sections?: https://www.ibm.com/docs/en/zos/2.4.0?topic=programming-establishing-terminating-sessions-logical-units https://www.ibm.com/docs/en/zos/2.4.0?topic=units-establishing-parameters-sessions This might also help: https://www.ibm.com/docs/en/zos/2.1.0?topic=programming-3270-information-display-system https://www.ibm.com/docs/en/zos/2.1.0?topic=terminals-session-parameter . mentions query support So you need to keep in mind that there are different protocol levels in your communications: a. VTAM (accepting a connection fron a LU, setting or accepting VTAM session parameters, sending/receiving data etc) b. device commands (not 3270 data stream). For a local 3270 this was the CCW opcode, for remote the codes were different: write local x'01', remote x'F1' VTAM uses the remote codes (and translates them to local if the target is a local 3270). c. the 3270 data stream I believe all the following are TSO macros.. > GTSIZE Determine terminal screen dimensions > GTTERM PRMSZE=PRIMSIZE,ALTSZE=ALTSIZE,ATTRIB=TERMATTR > STFSMODE ON,NOEDIT=YES Once you are connected to the 3270, the Read Partition is just "normal" (from VTAM's point of view) communication with the LU/device. > 4. Issue Read Partition (Query): But TPUT and TPG are TSO macros. > TPUT (1),(0),R Reset the Attention IDentifier > TPG QUERY,L'QUERY,NOEDIT,WAIT Issue Query The escape indicates that the next byte is the device command (pseudo-CCW opcode) so this is level (b) info while the following bytes are 3270 data stream. The F5 below after the 27 is the remote code for erase write. VTAM will translate this if needed for local 3270s. > RESETAID DC X'27F5C3' Escape, Erase/Write, WCC for resetting AID and > MDTs Hum... perhaps the F3 is level (b) and the escape isn't needed? > QUERY DC X'F3000501FF02' Read Partition structured field PS: All the mention of TSO/VTAM has lost the idea that there was at one time TSO/TCAM which also supported the TSO 3270 related macro calls. So those are really TSO macros and VTAM just happens how the connection is made inside of TSO. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
