Many operating systems provide text-based facilities for user interaction. Unix has a number of shells which accept text commands, and the SBC5206 monitor similarly accepts text commands and prints information in text form. Software programs also make extensive use of text i/o. It is therefore important to know how to write programs which can input and output text.
As described in HLAB6, the dBUG monitor has some built-in routines for text I/O. These routines are accessed via the TRAP mechanism. The standard C library also contains routines for text I/O, such as printf (see HLAB6).