  This is the Turbo Basic Interpreter.This is the one that runs on XL andXE series machines; see Frost Basicfor the version that runs on older(800 series) hardware.    This program is much more feature-full than Atari Basic, and is reputedto be completely upward compatible,as well as 3-5 times faster.  Also see the Turbo Basic compiler,the compiler and runtime system fora 10-15 (!) times speed improvement.