Visi On (also known as VisiOn) is an operating environment for IBM PCs and compatibles running DOS, developed by VisiCorp and released in December 1983.

Visi On was the first piece of software with a graphical user interface (GUI) for the IBM PC platform.

Visi On was never popular, as it had steep minimum system requirements for its day, but it was influential in the development of later GUIs like Microsoft Windows.

[3] In the spring of 1981, Personal Software was cash-flush from the ever-increasing sales of VisiCalc, and the corporate directors sat down and planned out their future directions.

Dan Fylstra led a technical discussion on what sorts of actions the user would need to be able to accomplish in order for their products to be truly integrated.

An experimental port to the ill-fated Apple III was completed in November, and after that, development work shifted to the DEC VAX, which had cross-compilers for a number of different machines.

In early 1982 Personal Software changed their name to VisiCorp, and was betting much of the future success of the company on Visi On.

It was fully mouse-driven, used a bit-mapped display for both text and graphics, included on-line help, and allowed the user to open a number of programs at once, each in its own window.

[5] Tom Powers, VisiCorp's new VP of marketing, pushed for the system to be demonstrated at the fall COMDEX show in 1982.

Terry Opdendyk, the president hand-picked by the early venture capital investors, had an extremely autocratic management style that led to the departure of many key executives.

Combined with the exodus of major portions of the senior executive staff and the ongoing battle with VisiCalc's developers, VisiCorp was soon in serious financial difficulty.

Adding to the release's problems was Bill Gates, who took a page from VisiCorp's book and announced that their own product, Microsoft Windows, would be available in May 1984.

This muddied the waters significantly, notably when he further claimed it would have a similar feature set, didn't require a hard disk, and cost only $250.

[12] Sales were apparently very slow; in February 1985, VisiCorp responded by lowering the price of the basic OS to $99, knowing that anyone purchasing it would also need to buy the applications.

Following declining VisiCalc sales and low revenues from Visi On, in November 1985, the company merged with Paladin Software.

First, loaded in text mode, made mouse registers accessible to the embedded driver, which translated coordinates to cursor position.

Visi On applications were written in a subset of C VisiC, and a third-party could have ported the core software (VisiHost, VisiMachine virtual machine, VISIONXT.EXE in IBM PC DOS version) to Unix, but that never occurred.