IBM TopView
(重定向自TOPVIEW)

TopView is a text-mode PC DOS multitasking, object-oriented windowing environment written by IBM, announced in August 1984 and shipped in March 1985. TopView provided an operating environment that allowed users to run more than one application at the same time on a PC. IBM demonstrated an early version of the product to key customers before making it generally available, around the time they shipped their new PC AT computer.