Microsoft committed to delivering a disk operating system (DOS) to IBM for the original IBM PC in 1980, although they had not yet developed one, and Allen spearheaded a deal for Microsoft to purchase QDOS (Quick and Dirty Operating System) written by Tim Paterson who was employed at Seattle Computer Products. As a result of this transaction, Microsoft secured a contract to supply the DOS that ran on IBM's PC line, which opened the door to Allen's and Gates' wealth and success.