VisiCalc was the first spreadsheet program for personal computers. It is regarded as a pioneer in the development of PCs from a hobby object to a tool in business.
The concept comes from Dan Bricklin. The software was developed jointly with Bob Frankston and 1979 by the company 's Personal Software (later renamed VisiCorp ) for the Apple brought to market II. The program allowed the use of the Apple for flexible, business calculations, on the first occasion for users without programming skills. This contributed to the decision of the then large computer manufacturer IBM to develop their own personal computer. The programmed in assembler of 6502 processor program ranged from 32 Kbytes main memory of the Apple II. As a result, VisiCalc was also for Apple III, Atari computer, the Commodore PET, the TRS -80 and finally the Intel 8086 processors, and thus the IBM PC, adapted. In a patent application, however, the developer of the program waived, as they, the cost appeared compared to the chances of obtaining a patent is too high. This is due to that in the late 1970s still quite high demands on a patent for inventions which are realized by software existed (see also software patent).
The legend says that Bricklin, an MBA student at Harvard Business School, his professor observed in an extensive calculation on the panel, said he noticed that every time a parameter was changing, wiping out a whole series of tabular intermediate results was and to recalculate. Bricklin had the idea that the process could be implemented on a computer, where the parameters, intermediate results and results displayed in tabular form and the results of underlying formulas would be entered into the table fields.