3290 in partitioned format mode

Support of 3290 partitioning and scrolling is provided for devices defined to IMS as SLU 2 terminals. Partitioning and scrolling are not provided for devices using non-SNA VTAM®.

Partition initialization options and paging

You can choose one of three different options for initializing the partition set and paging. The option you select determines how many logical pages of the output message are presented to their appropriate partitions at the initial transmission of a message to a partition formatted screen. (An output message consists of one or more logical pages, each destined for a particular partition according to the DPAGE specifying that partition.) The option also determines how paging requests present additional logical pages to their appropriate partitions. You can specify the option on the PAGINGOP= operand of the partition descriptor block (PDB) statement.

The three options are:

Option 1

The initial data stream presented to the 3290 LU consists of the first logical page of the output message, which is mapped using the DPAGE to the appropriate partition. Thereafter you control all paging with keyed-in paging requests. You use the PA1 and PA2 keys just as in standard, non-partitioned mode. The terminal can be using basic paging support or OLP.

When you request the next logical page, MFS gets the next sequential logical page and sends it to its associated partition. It does not matter which partition is active. A request for the next page results in the next sequential page in the message being sent to the inputting (active) partition or to another partition.

For example, if you enter =+1, the next logical page in the message is presented to the appropriate partition, whatever that partition might be. If you enter =+3, the page that is sequentially third from the last logical page presented is presented next.

Option 2

The initial data stream presented to the 3290 LU consists of the first logical page of the message and additional logical pages in sequence until the second logical page of any partition is reached, or until the end of the message. Thereafter you control all paging with keyed-in paging requests as described for Option 1.

Option 3

The initial data stream presented to the 3290 LU consists of the first logical page of each partition of the partition set. Thereafter you control all paging with keyed-in paging requests, with one crucial difference from Options 1 and 2: the order in which subsequent logical pages are presented to the partitions depends on the active partition, from which the request is entered. All requests for logical pages apply only to logical pages associated with the active partition.

For example, if you enter =+1, the next logical page destined for the active partition is presented—not necessarily the one that happens to be sequentially next in the message. This means that, for the 3290 operator, management of logical paging within the active partition is identical to paging support in a non-partitioned environment.

Regardless of the option chosen, one partition is active after the initial data stream is sent. The active partition is the one in which the cursor is located.

An ACTVPID operand might have been specified on one of the DPAGEs that points to an initialized partition. The ACTVPID allows the application program to declare which partition is the active partition. If option 2 or 3 is being used and data has been sent to several partitions, it is possible that more than one partition has been specified by ACTVPID keywords. In that case, the last partition activated is the active partition. If no ACTVPID keywords are encountered, the active partition is the partition defined by the first partition descriptor (PD) statement in the PDB.

Clearing the display

There are two levels of clearing the screen and buffer:

The CLEAR key (X'6D') resets the 3290 to base state, (non-partitioned mode), sets the buffer positions to null, and places the cursor in the upper left corner of the screen. It also places the active message back onto the queue and deletes the control block structure that was created for partitioning.
The CLEAR PARTITION key (X'6A') resets only the active partition buffer to nulls and clears the active partition viewport. It also places the cursor in the top left corner of the partition. The partition is considered unformatted; any input from it is considered unformatted by MFS and is processed by basic edit.

The JUMP PARTITION key

Using the JUMP PARTITION key, you can move from one partition to the next, in the order that the PD statements define the partitions in the PDB.

Movement between partitions is determined by the order of the PD statements, not by the order of the associated partition identifier (PID) values.

The partition to which the cursor moves becomes the active partition. Using this key causes no interaction with the host.

Scrolling operations

The VERTICAL SCROLLING keys cause the data to move up or down in the viewport, so that different parts of the presentation space appear in the scrolling window. The scrolling window is the portion of the presentation space that is mapped to the viewport at a given time. If the viewport has the same depth as the presentation space, the viewport is nonscrollable. If the viewport depth is smaller than the presentation space, it is scrollable.

The amount scrolled each time depends on what is specified by the SCROLLI keyword on the PD statement. The default scrolling increment is one row. Scrolling causes no interaction with the host.