Philipp Matthäus Hahn - mechanical calculator Eldon C. Hall - Apollo Guidance Computer Joseph Halpern Richard Hamming - Hamming code, founder of the Association for Computing Machinery Jiawei Han - Data mining Juris Hartmanis - computational complexity theory Johan Håstad - computational complexity theory Les Hatton - software failure and vulnerabilities He Jifeng - provably correct systems Martin Hellman Gernot Heiser - Development of L4 and founder of OK Labs James Hendler - Semantic Web John L. Hennessy - computer architecture Andrew Herbert Danny Hillis - Connection Machine Geoffrey Hinton Julia B. Hirschberg - Computational Linguistics C. A. R. Hoare - Logic, rigor, Communicating sequential processes (CSP) John Henry Holland - genetic algorithms Herman Hollerith - invented recording of data on a machine readable medium, using punched cards John Hopcroft - compilers Admiral Grace Hopper - compilers, COBOL Alston Householder David A. Huffman - Huffman code