Installation and maintenance of PostScript fonts

One of the advantages of PostScript is its ability to manage fonts. Fonts are stored in outline form in the Type 1 format, either on the printer or on a computer that communicates with a printer.

When a document is printed, the PostScript interpreter generates each character as needed (in the appropriate size) from the outline description of it. If a font required for a document is not stored on the printer being used, it must be transmitted to that printer before the document can be printed. This transmission process is called downloading fonts.

Fonts are stored and accessed in several ways.

• Fonts may be stored permanently on a printer. These printer-resident fonts may be installed in ROM on the printer by the manufacturer. If the printer has a disk, fonts may be installed on that disk by you (that is, by the Print Service administrator). Most PostScript printers are shipped with 35 standard fonts, although less expensive models have only 13.
• A font may be permanently downloaded by being transmitted to a printer using a special PostScript programming technique using the exitserver operator. A font downloaded in this way will remain in the printer memory until the printer is turned off. Memory allocated to this font will reduce the memory available for PostScript print requests. Use of exitserver programs requires the printer system password and may be reserved for the printer administrator. This method is useful when there is continual use of a font by the majority of print requests serviced by that printer.
• Fonts may be prepended to a print request by the user and be transmitted as part of the user print request. When the document has been printed, the space allocated to the font is freed for other print requests. The font is stored in the user's directory. This method is preferable for fonts with limited usage.
• Fonts may be stored on a system shared by many users. These fonts may be described as host-resident. This system may be a server for the printer or may be a system connected to the printer by a network. Each user may request fonts in the document to be printed. This method is useful when there are a large number of available fonts or when there is not continual use of these fonts by all print requests. If the fonts will be used only on printers attached to a server, store them on the server. If the fonts are to be used by users on one system who may send jobs to multiple printers on a network, store them on the users' system.

The print service provides a special download filter to manage fonts using the last method in the list.

The print service can use troff width tables for the 35 standard PostScript fonts that reside on many PostScript printers, for use by the dpost program.