80-dpi (normal/expanded-mode graphics)The Xdpi box contains the value that specifies the horizontal master unit. This value is the least-common multiple of the selected horizontal cursor-movement command and the supported graphics resolutions.
In the example for the Diconix printer, the horizontal master unit is 960 dots-per-inch (dpi). This value is the least-common multiple of the following graphics and cursor-movement resolutions:
80-dpi (normal/expanded-mode graphics)
160-dpi (normal/expanded-mode graphics)
320-dpi (normal/expanded-mode graphics)
12-cpi (default font-character width)
A minidriver typically supports three graphics resolutions: low, medium, and high. In the case of the Diconix, there are four horizontal graphics resolutions: 80, 96, 160, and 320. Because the 96-dpi resolution does not factor evenly into any of the others, this resolution has not been used. The remaining three values (80, 160, and 320) are used to support horizontal graphics resolutions. In the case of the HP LaserJet IIP printer, each of the supported graphics resolutions (75, 150, and 300) factor evenly into the specified least-common multiple of 300.
Many dot-matrix and laser printers support commands that move the cursor (or print head) horizontally across the page; however, some dot-matrix printers do not. In this case, the Universal Printer Driver uses the space character from the narrowest printer font to move the cursor (or print head) horizontally across the page. (For more information about the horizontal cursor-movement command, see Chapter 4, “Specifying Control Information.”) Because Diconix printer falls into the latter category, the space character from the narrowest printer font (a 12 pitch font) is selected as the “horizontal space command.” This means that the resolution of the horizontal cursor-movement command for the Diconix printer is 1/12th of an inch.
The Xdpi box contains the value 960. This value specifies the least-common multiple of the selected graphics and horizontal-movement resolutions.
The Xdpi box contains the value 300. This value specifies the least-common multiple of the selected horizontal resolutions.