Wikipedia
SuperCalc is a CP/M-80 spreadsheet application published by Sorcim in 1980. Visicalc was the first-ever spreadsheet program but was never made available for the popular CP/M operating system. SuperCalc was created to fill that void and market opportunity. It was originally bundled (along with WordStar) as part of the CP/M applications package included with the Osborne 1 portable computer. It quickly became the de facto standard spreadsheet for CP/M and was ported to MS-DOS in 1982.
An improvement over VisiCalc (though using much the same command structure using the slash key), SuperCalc is notable for being one of the first spreadsheet programs capable of iteratively solving circular references (cells that depend on each other's results). It would be over 10 years after the introduction of SuperCalc before this feature was implemented in Microsoft Excel, although in Lotus 1-2-3, manual programming of iterative logic could also be used to solve this issue. According to the SuperCalc product manager, iterative calculations were added when Sorcim changed from binary-coded decimal to Binary math. Since the precision of the two math packages was different, some IF statements resolved differently, and iterative calculations helped solve this problem.
Versions of SuperCalc were later released for the Apple II family, for PCs running DOS, and, after Sorcim was bought by CA Technologies (CA) in the mid-1980s, for MS Windows (under the name CA-SuperCalc). The MS-DOS versions were more popular with many users than was the market-leading Lotus 1-2-3 because it was distributed without copy protection (as well as being priced lower).
By the release of version 3 in March 1987, a million users were claimed. New versions were published into the early 90s after which Excel effectively came to dominate the spreadsheet market.