Development of the PowerPC 601 chip started in October 1991 and was completed in 21 months, with volume production starting in July 1993. The first computers to ship with a PowerPC chip were a line of IBM RS/6000 workstations in September 1993. Many Macintosh application developers used these machines for development of the initial PowerPC ports of their products, as Macintosh-based PowerPC development tools were not ready. The PowerPC 603 (which focused on lowering power usage) and 604 (which focused on high performance) projects were also underway at the same time.