What Are Windows and Virtual Screens?

A window is an area on the physical screen where virtual screen data can be displayed and manipulated. A window lets you see what is in a virtual screen.

A virtual screen can be thought of as a presentation space where data can be stored. A virtual screen (vscreen for short) simulates a physical screen, but is not confined to the size of the physical screen.

When you are looking at a window, you are actually viewing a virtual screen. Depending on the size of the window and the size of the virtual screen, you may be seeing a portion of the virtual screen or the entire virtual screen. For more information on virtual screens, see the VSCREEN DEFINE command in z/VM: CMS Commands and Utilities Reference.

Because a window shows you a portion of a virtual screen, you can perform several operations on the data in a virtual screen, and view the results in the window connected to the virtual screen. The characteristics of virtual screens that you can manipulate include:
  • Reserved areas for information such as titles and PF key descriptions
  • Color and highlighting
  • Options to log data into a file.
The following diagram illustrates the relationship between the physical screen, a window, and a virtual screen.
Figure 1. A Window into a Virtual Screen
The figure shows a virtual screen containing lines 1 through 25. Lines 20 through 23 of the virtual screen are displayed in a window on the physical screen.

When working with windows, you do not have to be concerned with the internal interactions between windows and virtual screens. However, as you become more familiar with how they work, you may find it useful to manipulate information by using the CMS commands for windows and virtual screens. Some of these commands will be discussed in this section. For more information on each command, see z/VM: CMS Commands and Utilities Reference.