DEF SEG Statement Programming Example DEFSG_EX.BAS is a program file in the subdirectory ADVR_EX that illustrates the DEFSG statement. To look at the program in the View window and, optionally, to run it, load DEFSG_EX.BAS using the File menu's Open Program command. The program uses DEF SEG, PEEK, and POKE to turn the CAPSLOCK key on and off. Note: The program contains hardware-specific instructions. It works correctly on IBM PC, XT, and AT computers.