Epson Printer's Graftrax
Several readers have inquired about the review of the Graftrax-80, published in the December 1982 issue of COMPUTE!. Specifically, they want to know if it is possible to redefine the MX-80 codes to approximate those of the Centronics 737. That way, software written for the 737 could run without modification.
The Epson MX-80 with Graftrax-80 can redefine its escape codes. These are printer functions controlled by sending the escape character, CHR$(27), and then a letter such as "E" for Enhanced printing. There are many other functions, however, that are controlled by sending an ASCII value less than 32 (a control character), such as CHR$(14), which signals double-wide characters. These functions cannot be redefined.
Current MX-80 printers are being shipped with Graftrax Plus. While Graftrax Plus improves on Graftrax-80 by adding underlining, super- and sub scripting, and faster graphics, some functions of Graftrax-80 were dropped to make room for the enhancements. Epson feels that those functions were not used very often anyway. Specifically, these functions do not carry over from Graftrax-80 to Graftrax Plus: TRS-80 graphics, Vertical Tab, and escape code redefinition.
You can find out which version you have by sending the printer a CHR$(129) With something like LPRINT CHR$(129). I f you get a small graphic box, you've got Graftrax-80. If you don't know whether you have any kind of Graftrax, send the printer:
LPRINT CHR$(27);"4 Hello there!"
If you get italics, you've got Graftrax.