Strategi Applet: 132 Column vs. 80 Column Screens

Product: Strategi
Modified Date:


The Strategi 5250 Emulation Applet has supported 132-Column emulation since Version 1, Release 1. This is a great addition to our original BusinessLink For Java emulation applet, which only supported 80-column display. However, on some monitors and at certain resolutions, the font on the 132-column screen is very small, and often unreadable.

The Problem

This problem is the result of several issues, which, when combined, produce an undesirable result.
  • In order for the emulation applet to display 5250 screens properly, it must use a fixed width font. If it used variable width fonts, the columns would not be aligned properly.
  • The Java applet must use a font which is likely to exist on the PC it is running on. In practice, this means that it must use Courier, because this is the only fixed width font available almost without fail on all Windows PCs. So, by default, the applet uses Courier. There is an applet parameter that allows you to specify what font to use. However, this is of limited use, because the Java Virtual Machine (JVM) in most browsers can only see a limited range of fonts. In fact, if the font you specify is not accessible, the JVM will choose an alternative, which is often not fixed width.
  • Finally, Courier only has a certain number of pitches, or sizes, at which it can be displayed.
So, when our Java applet attempts to display a screen that is 132 columns wide, it must choose the largest possible pitch of Courier for which all 132 characters will fit within the bounds of the applet window. If the window is maximized in a 800x600 Windows screen, the largest possible font size for which all 132 characters can fit on the screen is quite small on some monitors.

The Solution

To make these screens readable, turn off 132 column support. This will mean that only 80 column screens will be available. Most 132 column screens will be displayed in 80 column mode in such a way that one can position to the rightmost 80 columns or the leftmost 80 columns.

This is done by setting the applet parameter "allow_132_column" to "no". So your html page that loads the Java applet will need to have this line added (or an existing line for this parameter changed to look like):

<PARAM NAME=allow_132_column VALUE=no>

** End of Technical Support Bulletin **