Device errors in full-screen mode

GDDM V3R2 Base Application Programming Guide

Device errors in full-screen mode

GDDM V3R2 Base Application Programming Guide
SC33-0867-01

Under TSO in full-screen mode, non-full-screen output to the terminal can cause some full-screen transmissions to be "discarded" or wrongly interpreted. In some circumstances, this can cause device errors (displayed in the Operator Information Area of the terminal as "X PROGnnn").

After non-full-screen output has been received at the terminal, it is possible for more partial GDDM transmissions to occur before GDDM is able to begin retransmission of the screen contents; see "Reshow key processing in full-screen mode" in topic C.3.3.

In some circumstances, such partial GDDM transmissions may no longer be valid, and may cause device errors; for example:

A partial transmission may contain a reference to a PS set. The PS set may not have been initialized because:
- The particular PS set has not been used since the device was powered on, and
- The GDDM transmission initializing the PS set was discarded by TSO in favor of a non-full-screen message.
A partial transmission may assume the existence of a specific partition state on a 3290. The partition state may not exist because the GDDM transmission creating the partition state was followed by non-full-screen output that cleared the screen and thus destroyed the partition state.

If such device errors occur ("X PROGnnn" displayed in the terminal Operator Information Area), the terminal user should press the ENTER key to acknowledge the transmission. More partial transmissions (and more device errors) may occur until GDDM receives the reshow request, at which time GDDM automatically reconstructs the entire screen contents.

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