vrs writes: It was originally written by Tim Patterson of Seattle Computer Products, as 86-QDOS (Quick and Dirty OS). The initial purchase by Microsoft was for $15,000 IIRC, but full rights to the OS were purchased later for a larger sum. Patterson was originally planning on including multitasking, but did not due to time constraints. The OS gained tree-structured directories and I/O redirection/pipes (< > >> |) in 2.0 (inspired by UNIX), and a major rewrite for 5.0 (I believe this rewrite was largely the work of Charles Simonyi, but could not be sure). Tim Patterson was hired by Microsoft for a period of time. John John P. Willis Coherent Logic Development