Apple LaserWriter 12/640 PS - Manual (Page 356)

PostScript fonts
PostScript is a page-description language that defines the characters, symbols,
and images that appear on each page of a document. A PostScript font comes
as a pair of fonts: an outline font for the printer and a corresponding
bitmapped font for displaying type on your screen.
No bitmapped font, no menu entry: If your system doesn’t have the bitmapped
font, the PostScript font name won’t appear in your font menu.
The LaserWriter 12/640 PS is designed specifically to work with PostScript
fonts. Even printers that are not PostScript printers can use PostScript fonts if
you have Adobe Type Manager software installed. Adobe Type Manager uses
printer fonts to generate clean-looking screen text at any size. (Adobe Type
Manager is included with your LaserWriter 12/640 PS software.)
IMPORTANT Adobe Type Manager is not an Apple product. It is made and
supported by Adobe Systems Incorporated. Only the version that comes with
Mac OS system software version 7.5 is supported by Apple.
PostScript printer fonts have no numbers associated with their names,
because a single font can be scaled to any size. Many companies make
PostScript fonts; the following illustration shows icons for Adobe, Bitstream,
and Fontek PostScript fonts, plus a generic PostScript font icon.
331 Using Fonts With the Printer