After graduating from the Columbia School of Mines in 1879, he worked on the US census of 1880. The manual tabulating of its data took eight years, and Hollerith sought methods of automating this task. The result was the Hollerith code for recording data on punched cards and a tabulating machine that could read and count census items so encoded. This system was used successfully with the 1890 census, and Hollerith established the Tabulating Machine Company (one of the antecedents of IBM) in 1896 to market his inventions. Further enhancements included the keypunch (1901; see keyboard) and in 1906 an enhanced tabulating machine whose operation could be adjusted via a plugboard, giving it a limited programming capability. Hollerith machines continued to be developed during the 20th century by IBM and had an important influence on early computers, with punched cards or tape long being an important method of input, output, and data storage.