The Windows 32-Bit API:
An Overview
Since its original release in 1985, Microsoft® WindowsTM has become the leading graphical system for IBM® compatible personal computers. Version 3.0, released in May 1990, was a milestone that broke the 640K barrier of the Microsoft MS-DOS® operating system by running applications in protected mode, thus making it possible to develop much more sophisticated applications. This innovation spawned myriad applications and is responsible for the huge success of the Windows environment in the marketplace showcased by the volume of graphical applications sold (see Figures 1 and 2).
Between May 1990 and May 1991, more than 4 million copies of Version 3.0 were sold. International Data Corporation estimates that an additional 7.8 million copies will be sold during 1992. In addition, more than 66 thousand Microsoft Windows Software Development Kits version 3.0 have been shipped, a clear indication of the number of applications likely to appear during the next 12 to 18 months. By spring 1991, more than 1200 Windows-based applications were shipping.
Building on this achievement and on the success of independent software developers, Microsoft is extending and expanding the Windows environment so that Windows-based applications can run on a broad range of computing platforms — from low-end battery-operated portables to high-end RISC workstations and multiprocessor servers.
We are expanding Windows to make it fully 32-bit, and are adding additional operating system services. Microsoft Windows for Pen Computing and Microsoft Windows with Multimedia Extensions will also take advantage of new hardware technologies.
Windows Today
Today many people think of Windows as a graphical add-on to the familiar MS-DOS operating system they have used for years. This perception took much of the fear out of upgrading to Windows for the end user. But in fact, Windows is not limited by MS-DOS.
Windows is a complete operating system that provides extra features on top of MS-DOS and replaces certain MS-DOS features. Windows Version 3.0 does not use MS-DOS screen or keyboard I/O, does not use MS-DOS memory management, and can even bypass MS-DOS file I/O with new Windows-specific device drivers. Version 3.0 Enhanced-mode can handle 32-bit device drivers that are not limited by the infamous 640K MS-DOS barrier. These drivers talk through Windows to applications that are also not limited by the constraints of MS-DOS.
The advantage of being able to work with MS-DOS is that it preserves the value added by MS-DOS’s long life span (in computer years). Windows can run with MS-DOS TSRs, MS-DOS device drivers, and of course, it can run MS-DOS applications. Future versions of Windows will continue to be available on MS-DOS.
| 