Epson LQ-2550 User Manual - Page 132

Now you've seen how to design a character by placing dots on a grid and translating the dots to decimal equivalents. The last step in defining a character is to send this information to the printer. Sending information to your printer The printer loads characters in the print style (Letter Quality, draft, or proportional) that the printer is currently using. It also records whether italic, superscript, or subscript is turned on. This means that if you want to print a character in the italic mode, for example, you must have the italic mode turned on when you define the character. The command your printer uses to define characters is one of the most complex in its repertoire. The format of the command is this: ESC & 0 nl n2 do dl d2 data The ESC & is simple enough. The 0 (which is ASCII code 0, not the numeral zero in quotation marks) allows for future enhancements. At this time, it is always ASCII 0. With your printer, you can define many characters with a single command. The values nl and n2 are the ASCII codes for the first and last characters you are defining. If you are defining only one character, nl and n2 are the same. You can use any codes between 0 and 127 decimal for nl and n2, but it is best not to define decimal 32, which is the code for a space. Also, you can use letters in quotation marks instead of ASCII numbers for nl and n2. An example will show you how to specify nl and n2. If, for instance, you wanted to redefine the characters A through Z, nl would be A (or ASCII code 65) and n2 would be Z (or ASCII code 90). So the command ESC & 0 AZ (followed by the appropriate data) would replace the entire alphabet of capital letters. Following the specification of the range of characters to be defined in this command are three data bytes (do-&) that specify the width of the character and the space around it. The left space (in dot columns) is specified by do, and the right space is specified by dz. The second byte (dl) specifies the number of columns of dots that are printed to make up Using Software and Graphics 4-27