Epson 4100 manual American Standard Code for Information Interchange

D-2 Appendix D—Character Sets

The basic single-code operations are standard throughout the printer industry. The groupings of basic operations for character sets are called control code maps. (One common control code map is the ASCII* control code map.) There are slightly over 40 control code possibilities, of which a maximum of 32 or 33 control codes are ever assigned at any one time to a character set. For a 7-bit data byte, that leaves about "128 - 32 = 96" codes for characters.

The printer can print 428 different characters contained in a built-in ROM character library.

Most printers, including this one, use groupings of these ROM-based characters called character maps. The character maps make assignment of characters from the character library to the character set easier and more standardized between printers. One or more character maps can be assigned to make up the completed character set. An example of a standard character map is the 96-character ASCII map.

The standard ASCII character set, with control and character code assignments, is shown on Pages D-6 and D-7. Most character and control code mappings are variations of this standard character set for a 7-bit code. The ASCII character set covers the standard American computer keyboard.

*American Standard Code for Information Interchange