Editing Lotus Improv (section)

===Background===
The original spreadsheets were pieces of paper with vertical and horizontal lines on them, a customized [[worksheet]] intended for [[accounting]] uses. Users would enter data into rectangular areas on the sheets, known as cells, then apply formulas to the data to produce output values that were written down in other cells. A Berkeley professor, [[Richard Mattessich]], was a proponent of using spreadsheets for financial modeling and "what if" calculations for businesses, but noted that it could take so long to recalculate it to run a different scenario that the inputs would be out of date by the time the calculation was finished. In 1964 he proposed using a computer to run all of the calculations from the point of the change on, thereby updating the sheet in seconds, rather than days.{{sfn|Jelen|2005|p=6}}

Teaching the use of spreadsheet modelling was common in [[business school]]s, often using [[chalkboard]]s marked up with a layout similar to the paper versions. Using a chalkboard made it easier to fix errors, and allowed the sheet to be shared with a class. In 1979, [[Dan Bricklin]] was using such a device when he decided to attempt to computerize it on the newly introduced [[personal computer]]s. Joined by [[Bob Frankston]], the two created the first spreadsheet, [[VisiCalc]], and released it for the [[Apple II]] in 1979. When [[Benjamin M. Rosen|Ben Rosen]] of [[Morgan Stanley]] saw the program, he wrote that "VisiCalc might be the software tail that wagged the computer industry dog."{{sfn|Jelen|2005|p=12}}

VisiCalc was an enormous success, so much so that a huge number of clones appeared. One of these was written by a former VisiCalc programmer, [[Mitch Kapor]]. His version, [[Lotus 1-2-3]], would go on to be an even greater success than VisiCalc, in no small part due to the fact that it ran on, and was tuned for, the new [[IBM Personal Computer|IBM PC]].{{sfn|Jelen|2005|p=16}}  Lotus 1-2-3 shipped 60,000 copies in the first month,{{sfn|Jelen|2005|p=16}} and Lotus was soon one of the largest software companies in the world.