Visible Calculator VisiCalc was the first spreadsheet computer program for personal computers devised by VisiCorp and originally released for Apple II  in 1979 and considered to be Apple II's "killer app" selling almost 1 million copies. It was developed for the Apple II computer using a 6502 assembler.

VisiCalc used the A1 notation in formulas, as Dan Bricklin conceived VisiCalc while watching a Harvard Business School professor creating a financial model on a blackboard that was ruled with vertical and horizontal lines to construct a table of cells in which he wrote formulae and data. Bricklin's innovation was that he could replicate the process in a computer's "electronic spreadsheet".

Bob Frankston joined Bricklin and formed the Software Arts company, and developed the VisiCalc program in two months in 1978–79. The Personal Software company began selling VisiCalc in mid-1979 for under $100. It required an Apple II with 32K of random-access memory (RAM), and supported saving files to magnetic tape cassette or to the Apple Disk II disk.

Tandy Corporation used VisiCalc on Apple IIs with other software that supported its data sharing Data Interchange Format (DIF). The Microsoft BASIC interpreter supplied with most microcomputers that ran VisiCalc  allowed BASIC programmers to add functions that VisiCalc lacked, such as trigonometric functions.

Releases for Apple:

1979: Apple II

1980: Apple III, Apple II

1982: Apple III, Apple IIe—VisiCalc Advanced Version

Platform: Apple II, II Plus 48Kb RAM  Disk 5.25

               TV set or other viseo monitor

               Optionally, the Apple Language System, Compatible Printer

               OS: DOS  3.2 or 3.3     

Application Software (AS:) Spreadsheet

Version: 1981

Related Items in the Collection:

Visicalc III

Microsoft Multiplan

FlashCalc

Microsoft Excel 2.2

Information About VisiCorp Personal Software: