Seymour I. Rubinstein was an employee of early microcomputer company IMSAI, where he negotiated software contracts with Digital Research and Microsoft.

After leaving IMSAI, Rubinstein planned to start his own software company that would sell through the new network of retail computer stores.

He founded MicroPro International Corporation in September 1978 and hired John Robbins Barnaby as programmer, who wrote a word processor, WordMaster, and a sorting program, SuperSort, in Intel 8080 assembly language.

After Rubinstein obtained a report that discussed the abilities of contemporary standalone word processors from IBM, Xerox, and Wang Laboratories, Barnaby enhanced WordMaster with similar features and support for the CP/M operating system.

[2] An exhausted Barnaby left the company in March 1980, but due to WordStar's sophistication, the company's extensive sales and marketing efforts, and bundling deals with Osborne and other computer makers, MicroPro's sales grew from $500,000 in 1979 to $72 million in fiscal year 1984, surpassing earlier market leader Electric Pencil.

By 1984, the year it held an initial public offering, MicroPro was the world's largest software company with 23% of the word processor market.

PC Magazine wrote in 1983 that MicroPro's "motto often seems to be: 'Ask Your Dealer'",[8] and in 1985 that[9] Almost since its birth 4 years ago, MicroPro has had a seemingly unshakable reputation for three things: arrogant indifference to user feedback ("MicroPro's classic response to questions about WordStar was, "Call your dealer"); possession of one of the more difficult-to-use word processors on the market; and possession of the most powerful word processor available.By late 1984 the company admitted, according to the magazine, that WordStar's reputation for power was fading,[9] and by early 1985 its sales had decreased for four quarters while those of Multimate and Samna increased.

In September 1983 it published WordStar clone NewWord, which offered several features the original lacked, such as a built-in spell checker and support for laser printers.

Besides word-wrapping (still a notable feature for early microcomputer programs), this last was most noticeably implemented as on-screen pagination during the editing session.

Using the number of lines-per-page given by the user during program installation, Wordstar would display a full line of dash characters onscreen showing where page breaks would occur during hardcopy printout.

[19] Two files were required: The writer would insert placeholders delimited by ampersands into the master document, e.g., &TITLE&, &INITIAL&, &SURNAME&, &ADDRESS1&.

[18] Originally only a report generator, the software was later expanded as a full database application suite comprising DataStar and ReportStar.