Because Dan Bricklin and Bob Frankston implemented VisiCalc on the Apple II in 1979 and the IBM PC in 1981, the spreadsheet concept became widely known in the early 1980s. VisiCalc was the first spreadsheet that combined all essential features of modern spreadsheet applications (except for forward referencing/natural order recalculation), such as WYSIWYG interactive user interface, automatic recalculation, status and formula lines, range copying with relative and absolute references, formula building by selecting referenced cells. Unaware of LANPAR at the time "PC World" magazine called VisiCalc the first electronic spreadsheet.