Interactive computing system developed by RandCorporation for AdvancedResearchProjectsAgency? in the sixties. It's an early and very pure example of a GraphicalUserInterface system: all user interaction was through a graphical CathodeRayTube? display and the first modern GraphicsTablet?. The computer used was an IbmSystemThreeSixty/44. (The 360 was dedicated to supporting a single GRAIL terminal, making it an enormously expensive PersonalComputer. Like the XeroxParc work that came after it, GRAIL was explicitly intended to use a lavish hardware budget to explore the possiblities of computer systems that would become affordable later.)
The system provided the user with GrailLanguage, a high-level, flowchart-based GraphicalProgrammingLanguage descended from JossLanguage. The user drew and labelled the flowchart using the stylus; the system performed incremental shape and printed-character recognition on the user's input. As with SketchPad insightful InteractionDesign, clever SystemsProgramming? and then-lavish but now-miserly computer resources seem to have combined to produce a capable system with an intuitive and radically clean UserInterface.
GRAIL is one of the systems credited by AlanKay as an influence on SmalltalkLanguage; see EarlyHistoryOfSmalltalk.