Browse Prior Art Database

Dynamic Sequence Change in Switching Logical Terminals

IP.com Disclosure Number: IPCOM000117877D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 114K

Publishing Venue

IBM

Related People

Hayashi, Y: AUTHOR [+2]

Abstract

Disclosed is a method to dynamically change the displaying sequence of Logical Terminals (LTs) in 3270 terminal emulation software which has Multiple Logical Terminals (MLTs) capability. The displaying sequence is changed when the host computer system updates the screen of an LT which has been inactive, or in other words, has lost focus and, therefore, whole or parts of its screen have been hidden behind the screens of other LTs. With this method, an LT whose screen is updated during an inactive period is given higher priority in the queue to be activated or displayed wholly.

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Dynamic Sequence Change in Switching Logical Terminals

      Disclosed is a method to dynamically change the displaying
sequence of Logical Terminals (LTs) in 3270 terminal emulation
software which has Multiple Logical Terminals (MLTs) capability.  The
displaying sequence is changed when the host computer system updates
the screen of an LT which has been inactive, or in other words, has
lost focus and, therefore, whole or parts of its screen have been
hidden behind the screens of other LTs.  With this method, an LT
whose screen is updated during an inactive period is given higher
priority in the queue to be activated or displayed wholly.

      MLT is a capability to logically realize multiple terminals on
one personal computer or workstation.  The screens of those logically
achieved terminals are mapped onto the physical display screen of a
personal computer or a workstation.  Since the space of the physical
screen is limited, those LT screens overlap each other; only one of
the LT screens which has the exclusive right to receive keystrokes
from the keyboard is displayed on top of the other screens; i.e., the
remaining LT screens may be wholly or partially hidden by others.

      The LT which receives keystrokes is called the 'active LT'.
The emulation software has a queue which chains all LTs; the LT at
the top of the queue is the active LT.  Users can change the active
LT with a key.  The functions of the key are:
  o  to move the currently active LT to the end of the LT queue, and
  o  to make active the LT being pushed out to the top of the queue.

      To dynamically change the displaying sequence or, in other
words, the activating order of the LTs, a pointer and a flag are
added.  The new pointer points the LT in the queue whose screen got
the latest update by the host system.  The flag is placed in each
LT's control block in the queue, and it indicates that the host
system has updated the corresponding LT's screen during the time it
was inactive.  The usage of the pointer and the flag is described
using Fig. 1, Fig. 2, Fig. 3 and Fig. 4.  The Figures assume, for
instance, that there are five LTs defined with the emulation
software.

      Fig. 1 shows the initial state.  There a...