Starting in the mid-1980s, several companies produced their own variations on the dBase product and especially the dBase programming language. These included FoxBASE+ (later renamed FoxPro), Clipper, and other so-called xBase products. Many of these were technically stronger than dBase, but could not push it aside in the market. This changed with the disastrous introduction of dBase IV, whose design and stability were so poor that many users switched to other products. At the same time, database products increasingly used the IBM-invented SQL (Structured Query Language). Another factor was user adoption of Microsoft Windows on desktop computers. The shift toward SQL and Windows put pressure on the makers of xBase products to invest in major redesign to provide new capabilities.