While a student at Harvard Business School, Bricklin co-developed VisiCalc in 1979, making it the first electronic spreadsheet readily available for home and office use. It ran on an Apple II computer, and was considered a fourth generation software program. VisiCalc is widely credited for fueling the rapid growth of the personal computer industry. Instead of doing financial projections with manually calculated spreadsheets, and having to recalculate with every single cell in the sheet, VisiCalc allowed the user to change any cell, and have the entire sheet automatically recalculated. This could turn 20 hours of work into 15 minutes and allowed for more creativity.