Personal computers made by Wang Laboratories. Wang's PCs had an operating system (based on MS-DOS) which was not compatible with the IBM PC. The Wang floppy disk format was compatible with the IBM PC. However, running an IBM "exe" program would generally crash a Wang PC unless a special Industry-Standard emulator program was running on the Wang. This program required the addition of a special card to the Wang PC. It enabled the Wang PC to run most, but not all, software written for the IBM PC. Most Wang software made use of two special keys: CANCEL and EXECUTE. These keys were used to carry out commands, make menu selections, and so on. The Wang OS was menu-driven.