His grandfather, Isadore Greenblatt was born in Soroca, Bessarabia. He wrote Mac Hack, the first computer program to play tournament-level chess and the first to compete in a human chess tournament. AI skeptic Hubert Dreyfus, who famous- ly made the claim that computers would not be able to play high quality chess, was beaten by the program, marking the beginning of "respectable" computer chess performances. In 1977, unbeaten chess champion Bobby Fischer played and won three games in Cambridge, Massachusetts against the computer program, and Fischer won all of them. He, alongwith Tom Knight and Stewart Nelson, co-wrote the Incompatible Timesharing System, a highly influential timesharing operating system for the PDP-6 and PDP-10 used at MIT. Later, he and Tom Knight were the main designers of the MIT Lisp machine. He founded Lisp Machines, Inc., according to his vision of an ideal hacker-friendly computer company, as opposed to the more commercial ideals of Symbolics. He felt compelled to implement a Fortran compi- ler for the PDP-1, which did not have one at the time. There was no computer time available to debug the compiler, or even to type it in to the computer. Years later, elements of this compiler (combined with some ideas from fellow TMRC member Steven Piner, the author of avery early PDP-4 Fortran compiler while workingforDigital Equipment Corporation) were typed in and "showed signs of life