Lotus 1-2-3 is a spreadsheet program from Lotus Software (now part of IBM). It was the IBM PC's first "killer application"; its huge popularity in the mid-1980s contributed significantly to the success of the IBM PC in the corporate environment.
The Lotus Development Corporation was founded by Mitchell Kapor, a friend of the developers of VisiCalc. 1-2-3 was originally written by Jonathan Sachs, who had written two spreadsheet programs previously while working at Concentric Data Systems, Inc. To aid its growth, in the UK, and possibly elsewhere, Lotus 1-2-3 was the very first computer software to use television consumer advertising.
1-2-3 was released on January 26, 1983, started outselling then-most-popular VisiCalc the very same year, and for a number of years was the leading spreadsheet for the DOS operating system. Unlike Microsoft Multiplan, it stayed very close to the model of VisiCalc, including the "A1" letter and number cell notation, and slash-menu structure. It was free of notable bugs, and was very fast because it was programmed entirely in x86 assembly language and bypassed the slower DOS screen input/output functions in favor of writing directly to memory-mapped video display hardware.
This reliance on the specific hardware of the IBM PC led to 1-2-3 being utilized as one of the two litmus test applications for true 100% compatibility when PC clones started to appear in the early- to mid- 80s. 1-2-3 was used to test general application compatibility, with Microsoft Flight Simulator being used to test graphics compatibility. Because all of a spreadsheet needs to be resident in memory, it also drove the race to utilize more memory, and extended memory and expanded memory techniques were needed to overcome the DOS limit of 640KB to allow larger spreadsheets - this was so important that a memory used/remaining indicator was displayed on-screen.
Data features included sorting data in any defined rectangle, by order of information in one or two columns in the rectangular area. Justifying text in a range into paragraphs allowed it to be used as a primitive word processor.
It had keyboard-driven pop-up menus as well as one-key commands, making it fast to operate. It was also user-friendly, introducing an early instance of context-sensitive help accessed by the F1 key.
Macros and add-ins (introduced in version 2.0) contributed much to 1-2-3's popularity, allowing dozens of outside vendors to sell macro packages and add-ins ranging from dedicated financial worksheets to full-fledged word processors. (In the single-tasking MS-DOS, 1-2-3 was sometimes used as a complete environment.) Lotus 1-2-3 supported EGA graphics on the PC/AT and VGA graphics on the PS/2. Early versions used the filename extension "WKS". In version 2.0, the extension changed first to "WK1", then "WK2". This later became "WK3" for version 3.0 and "WK4" for version 4.0.
Version 2 introduced macros with syntax and commands similar in complexity to an advanced BASIC interpreter, as well as string variable expressions. Later versions supported multiple worksheets, and were written in C.
There is also a version of 1-2-3 for the HP 200LX, a palmtop released by Hewlett-Packard.
1-2-3's intended successor, Lotus Symphony, was Lotus's entry into the anticipated "integrated software" market. It intended to expand the rudimentary all-in-one 1-2-3 into a fully-fledged spreadsheet, graph, database and word processor for Windows, but none of the integrated packages ever really succeeded. 1-2-3 migrated to the Windows platform, where it remains available as part of Lotus SmartSuite. By release 9 of Lotus SmartSuite, 1-2-3 had matched the capabilities of Excel. Current releases of 1-2-3 still have advantages over Excel such as database connectivity; however, lack of interest and support by IBM has led to its decline.