HES ran on an IBM 360/50 mainframe computer, which was inefficient for the task of running such a revolutionary system. Although HES pioneered many modern hypertext concepts, its emphasis was on text formatting and printing. HES research was funded by IBM but the program was stopped around 1969 and the program was reportedly sold to NASA's Houston Manned Spacecraft Center, which reportedly used the program for documentation on the Apollo space program. HES was discontinued and replaced by the FRESS (File Retrieval and Editing System) project.