PCL fonts can be supplied by two forms: cartridge font and soft font. Cartridge font plugs into a font cartridge slot in the printer. Soft fonts are transferred from a host computer into the printer's user memory (RAM). Soft fonts provide the maximum flexibility - you can download, make permanent or remove a soft font. After a soft font is downloaded and made permanent, the font resides in the memory until you explicitly send “remove” command or in the event of a power loss. Since the soft fonts reside in the RAM other than ROM, they can not survive a power loss. Thus, it is a good idea to download the soft font at the beginning of each print job. Each time the old font is replaced by the new one, and the font reloading only takes 1 to 2 seconds depending on the font size.

A font is a collection of characters that share similar characteristics. A font is described by its symbol set, spacing, height, pitch, style, typeface and orientation. The most important characteristics regarding a PCL font are symbol set, spacing, height, pitch and typeface.

Symbol Set

Symbol Set identifies the specific collection of symbols provided by a font. It can be criteria for selecting font. Each symbol set is identified by a number, called symbol set kind value.

Spacing

Fonts have either fixed spacing or proportional spacing. The Code 39 and OCR fonts included in this package have fixed spacing. The UPC fonts, on the other side, have the proportional spacing.

Pitch

Pitch is measured by the number of characters in a horizontal inch, character per inch or cpi.

Height

The height of a font is measured by points. Traditionally a point equals 1/72 inch. For Morovia PCL fonts, the actual physical size of a point varies depending on the typeface.

Typeface Family

Typeface identifies the design of the symbol. Morovia designates font family name based on the barcode format, height and whether the character contains human readable portion. The typeface family name always starts with MRV prefix, followed by a space, the barcode format, height option and text option.

For example, MRV Code39MA refers to a font family with the following characteristics: Code39; height option M with human readable; developed by Morovia Corporation.

You access the printer features by sending PCL commands. Due to its scope, this manual covers only basic explanation of PCL commands. If you are not familiar with PCL commands, you may want to obtain the [PCL Technical Reference Manual], part number 5021-0377 from HP.

A PCL command always begins with the ESC character (referred as <esc> throughout of this manual). The ASCII value for this character is 27. It is followed by one or two characters (called commands). A PCL command may contain parameters, and termination characters. For example, the following command selects a font with 12 points in height:

<esc>(s12V

The (s represents the Height command, 12 is the parameter and V is the termination character.

The method of communications between your program and printer varies from platform to platform. Fortunately, many platforms allow you treat printer as a normal file. Your program retrieves a file handle by passing a special name to the file open routine. To send the PCL command, your program writes to the file handle. For example, the following C statement writes a PCL command to the printer:

fprintf(prn, "\x1B(s%dV", height);