The standard Atari OS in ROM does not support any type of fonts. To use different fonts in applications, either the application has to have built-in support for some font format, or an add-on program is needed. This add-on program is called a GDOS, a Graphical Device Operating System. There are many different versions of GDOS.
The earliest versions of GDOS supported only GEM bitmap fonts (*.FNT). These versions include GDOS, AMC-GDOS (Atari), G-plus (Codehead) and Font-GDOS (Atari again). Font-GDOS (available for free) added caching to the font-manager, so not all fonts need to reside in memory at the same time.
After FontGDOS came FSM-GDOS. The FSM stands for Font Scaling Manager and allowed vector fonts to be used. The font-format for FSM-GDOS is not known (*.QFM and *.OTL files), and the only fonts available for it were a set of 15 Lucida fonts, including a symbol, a Hebrew, and Italic, Roman and Bold versions. FSM-GDOS was only included with Wordflair II and G-Man. FSM-GDOS also still supported GEM bitmap fonts.
After FSM-GDOS, Atari introduced SpeedoGDOS 4.0, using Speedo font scaling technology licensed from Bitstream. 14 fonts are included with this version (see 1.15). SpeedoGDOS 4.0 and 4.1 can use GEM bitmap, Atari encrypted and commercially encrypted Speedo fonts. As of version 4.2 also the publicly available X11 Speedo fonts can be used. SpeedoGDOS offers improved speed and reliability over FSM-GDOS, as well as track- and pair-kerning.
Recently Compo Software introduced SpeedoGDOS 5.x which supports GEM bitmap, Speedo, Truetype and Type 1 fonts. Included are 22 Speedo fonts (see 1.15).
Also recently introduced was NVDI 3.0 by Behne & Behne, which supports GEM bitmap, Speedo and Truetype fonts. The biggest difference when compared to SpeedoGDOS 5.x is the improved speed, because NVDI is written in Assembler instead of C. Only 2 fonts are included with NVDI 3.0.
These fonts are transparent to programs. There are a few other options that require support by the program using the fonts. Two major font formats are supported in this way on the Atari, namely Signum!2/Signum!3 fonts and Calamus fonts.
The Signum!2 font format is a bitmapped font format supported by many wordprocessors and some drawing packages. Amazing print quality on 9-needle printers. Many high quality designs are available in Signum!2 and Signum!3 format (Mostly German), especially for some special languages like Polish. There are also many PD fonts available in this format.
The Calamus (*.CFN) format was introduced by DMC, in their Calamus DTP program that uses soft-RIPping. The Calamus font format has no hinting since it is meant to be used on very high resolution type setting machines. Also supported by Digital Art's (DA's) software. Many professional designs are available in this format, as well as a lot of PD fonts.
File formats specific to the Atari platform:
Bitmapped Signum!2 screen font.
Bitmapped Signum!2 printer font for Laser and Deskjet printers.
Vector font table used by FSM-GDOS.
Bitmapped Signum!2 printer font for Hi-Res 9-needle printers (214*196 dpi).
Bitmapped Signum!2 printer font for 24-needle printers.
Vector font used by FSM-GDOS.