1/288-inch (line spacing)The Ydpi control contains the value that specifies the vertical master unit. This value is the least-common multiple of the selected line spacing and graphics resolutions.
In the example for the Diconix printer, the vertical master unit is 576 dpi. This value is the least common multiple of the following line spacing and graphics resolutions:
1/288-inch (line spacing)
1/96-inch (normal-mode graphics)
As mentioned previously, a minidriver for a dot-matrix printer typically supports three graphics resolutions: low, medium, and high. However, in the case of the Diconix printer, there are only two vertical graphics resolutions, and the higher of the two requires that a dip switch in the printer be toggled from its default factory setting. (Minidrivers should ideally support the default switch settings for printers. However, in some cases this may not be possible.) In addition, the higher resolution requires interlaced output in the y-direction. Because the higher resolution would force the user to alter the factory settings and because this higher resolution results in slower printing (due to the interlaced graphics), the lower resolution (96 dpi) was chosen.
The Diconix printer supports six line-spacing commands which provide the following vertical resolutions:
1/8-inch (line spacing)
7/72-inch (line spacing)
7/96-inch (line spacing)
1/6-inch (line spacing)
n/216-inch (line spacing)
n/288-inch (line spacing)
Of these resolutions, the finest (288 dpi) was chosen for the Diconix.
In the case of the HP LaserJet IIP, the resolution used for the line-spacing command and the vertical resolution for graphics output are equivalent (300 dpi).
The Ydpi box contains the value 576. This value is the least common multiple of the 1/288 inch Line Spacing command and the 1/96 inch vertical graphics resolution.
The Ydpi box contains the value 300.
Note:
A printer's aspect ratio is the ratio formed by the x-and the y-printer resolution values. The aspect ratio for most printers is 1 (for example, the HP LaserJet IIP supports a 300 dpi resolution in both the vertical and horizontal directions). However, in the case of the Diconix printer, this ratio is 3.333 (320/96) for the highest resolution. Whenever possible, avoid using aspect ratios greater than 2 in order to produce the highest quality.