VisiCorp was an early personal computer software publisher. Its most famous products are Visi On and VisiCalc.It was founded in 1976 by Dan Fylstra and Peter R. Jennings as Personal Software, and first published Jennings' Microchess program for the MOS Technology KIM-1 computer, and later Commodore PET and Apple II versions. It later published a wider variety of games and some applications programs. In 1979 it released VisiCalc, which would be so successful that in 1982 the company was renamed "VisiCorp". VisiCalc was the first electronic spreadsheet for personal computers, developed by Software Arts and published by VisiCorp. Visi On was the first GUI for the IBM PC.