IBM 4400 manual Bit Image Density

Bit Image Density

Bit Image Density

Bit Image Graphics mode may be printed in different dot densities selected by the following control codes:

•ESC K selects the Single Density mode.

•ESC L selects the Double Density mode.

•ESC Y selects the Double Speed, Double Density mode.

•ESC Z selects the Quad Density mode.

Bit Image Graphics mode was originally intended to be used on printers having 60 dpi (or 120 dpi) horizontal resolution and 72 dpi vertical resolution. Other print modes can be used, but the horizontal and/or vertical dimension might change and/or overlaps or gaps might appear. For details concerning available modes, see Chapter 4, “Serial Matrix Printer Protocol,” Chapter 5, “IBM Proprinter III XL Printer Protocol,” or Chapter 6, “Epson FX-1050 Printer Protocol.”

In Single Density Bit Image graphics from the Letter Gothic (DP) print mode, printed dot density is 60 dots per inch (dpi) horizontally and 72 dpi vertically. From the Courier (NLQ) print mode, horizontal dot density is 120 dpi and vertical density is 144 dpi.

The Double Density mode prints up to twice the number of dots per inch horizontally (up to 120 dpi from the Letter Gothic [DP] mode). The vertical dot density remains the same as in the Single Density mode. Double horizontal density requires twice the number of input data bytes to print the same length line as Single Density.

When the Double Density, Double Speed control code is received, the data can be printed at up to double the current horizontal dot density; but all adjacent dots are removed, which affects the final density of the printed image.

Quad Density characters are processed the same as Double Density characters. Each character is stored in successive dot columns, and successive pairs of data characters are logically OR'ed together. Quad horizontal density requires twice the number of input data bytes to print the same length line as Double Density.

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