Bill Gates marked Microsoft’s 50th Anniversary by unveiling the source code for Altair Basic, a programming language interpreter developed for the MITS Altair 8800 microcomputer. This 157-page PDF is available for download on Gates' blog. Altair Basic was created in 1975 by Gates, Paul Allen, and Monte Davidoff, who worked intensively for two months after being inspired by the Altair 8800. They chose to develop an interpreter instead of a compiler to provide instant feedback for novice programmers. MITS licensed the software from Gates and Allen, leading to the founding of Micro-soft. The full code document is now accessible, along with a web page featuring animations and graphics celebrating this early coding project.