Sinclair BASIC is a popular version of the BASIC (Beginner's All purpose Symbolic Instruction Code) programming language. Originally written for the ZX80, it is now available for a wide range of computers in native versions or via emulation. This is the history of its evolution. By then Kemeny and Kurtz had addressed the main criticisms of BASIC; that it lacked structure and encouraged bad programming habits, but the 4K and 8K versions for the Altair, written by Paul Allen and Bill Gates, were based on the original Dartmouth BASIC.