the multiple-register operations could use only R15. Intergraph's Clipper systems Intergraph sold several generations of Clipper systems, including both servers and workstations. These systems included the InterAct, InterServe, and InterPro product lines and were targeted largely at the CAD market. Fairchild promoted the CLIX operating system, a version of UNIX System V, for use with the Clipper. Intergraph adopted CLIX for its Clipper-based systems and continued to develop it; this was the only operating system available for those systems. Intergraph did work on a version of Microsoft Windows NT for Clipper systems and publicly demonstrated it, but this effort was canceled before release. Intergraph decided to discontinue the Clipper line and began selling x86 systems with Windows NT instead. References Intergraph history Instruction set architectures 32-bit microprocessors