Lotus 1-2-3

Lotus 1-2-3 was regarded as the "killer app" of the IBM PC in its early days, just as VisiCalc was for the Apple II platform. Both were spreadsheets which used a similar interface, still familiar to modern spreadsheet users, consisting of a matrix of rows and columns where the columns have letters and the rows have numbers, and a cell can be addressed by an address such as "B2".

After years of dominance of the spreadsheet market for PC/MS-DOS, 1-2-3 failed to successfully move over to the Windows platform, and was eclipsed by Microsoft Excel. When 1-2-3 was finally officially discontinued in 2013 (by IBM, which now owns Lotus), the general reaction was "What, they still made 1-2-3 until now? I thought it died a long time ago."

The original 1-2-3 files had a .wks extension. Version 2.0 originally used a .wk1 extension, but that was soon changed to .wk2, and from then on the number in the extension corresponded to the program version number. Lotus Symphony (the '80s version, not the unrelated 2000s version which used a variant of Open Office format) used a similar file format.

Format specs

 * Spec introduction
 * Summary of record types
 * Cell format encoding
 * The Formula Compiler
 * 1985 addendum

Import/export info

 * Tips for Importing Lotus 1-2-3 Files to Excel
 * Interfacing with 1-2-3 files in SAS/ACCESS

Other links

 * Wikipedia article