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Viewports
Up to three viewports can be selected on a page. Each viewport has its own character attribute, cursor
position, field attribute propagation, tab stops and scrolling region. All of the viewports are displayed on the
same screen and can be partitioned with a visual separator line. If the keyboard is associated with one viewport
and the host is associated with another, it is possible to receive data in two viewports simultaneously. The figure
below represents the entire page memory of a 48 line page (24 base page length times a multiplier of 2) and the
portion of the page that is viewable on the display screen, when “26 Lines” is selected. Notice that the label line
is visible in this mode.
Visual Effects Of Screen And Page Lengths
The combination of page and screen lengths influence the number of displayable data lines. For example, if the
page length is “50" (25 x 2), and the screen length is 44 lines, the number of data lines that are visible at any
one time is 43, with no label line. The other line is used for the top status line. On a 52 line screen, 50 of the 52
data lines are visible at one time.
If the page length is shorter than the screen length, then blank lines will be present below the data line or
status/label line. If the page length is larger than the allowable number of data lines, this will cause some of the
rows to be out of view. In order to bring them into view, “scrolling” or “panning” is used, as necessary. Scrolling
causes a new line to scroll into view when the cursor advances past the last row or first row on the page. If the
page is scrolled down, the top row of text is lost, and if scrolled up, the bottom row of text is lost (if Auto Scroll is
“on” in Setup). Text scrolled off of the screen is not recoverable.
If the current page or portion of the page is longer than the screen display or window in which it is displayed,
then local keystrokes can be used to “pan” the window up or down (Ctrl-ì and Ctrl-Å ). As a window is panned
up, the page appears to be moving down and the opposite is true when panning the window down. Text that is
panned off the screen is out of view, but is not lost.
The figure below represents the display screen with a 48 line page length on a 44 line screen, after panning the
window down 2 lines.
