Business Notes COMPUTERS

No computer software is more popular than Lotus 1-2-3, the electronic spreadsheet program that has sold 5 million copies since 1984. But Lotus Development Corp.'s domination of the $600 million U.S. market for such software has been threatened by an 18-month delay in the company's production of an improved program called Release 3. When the company, based in Cambridge, Mass., finally began shipping Release 3 last week, many experts realized that the program is essentially a new product rather than a simple upgrade. Boasts Lotus chairman Jim Manzi: "There's nothing like it on earth."

The primary advance of Release 3, which sells for $495, is its ability to link as many as 256 spreadsheets in one computer file, creating an almost three-dimensional effect in the way they can be combined to make different calculations. Lotus plans to offer a simpler version, called Release 2.2, within a few months.