Microsoft Announces Win32 Driver Model…

Microsoft PressPass – Microsoft Announces Win32 Driver Model; Windows Hardware Development Simplified

SAN JOSE, Calif., April 1, 1996 — Microsoft Corp. today announced the Win32® Driver Model, which provides a common driver architecture for the Microsoft® Windows® 95 and Windows NT®
operating systems. With the Win32 Driver Model, a single device driver can be written for both operating systems, making it faster and easier for hardware developers to create higher-quality drivers and innovative hardware at lower cost.

The Win32 Driver Model is a core technology for Microsoft’s Simply Interactive PC (SIPC), unveiled here today to leading PC hardware engineers and executives attending the Windows®
Hardware Engineering Conference (WinHEC 96). SIPC is the framework for PCs that are as simple and convenient to use as consumer appliances and will become the center of entertainment, communications and productivity in the home and office. SIPC technologies that will use the Win32 Driver Model include new Plug and Play device support for the USB and 1394 buses, as well as the OnNow initiative, which was also announced here today (see related release).

“The Win32 Driver Model is a critical step in our strategy for Windows 95 and Windows NT to share technologies,”
said Paul Maritz, group vice president of the platforms group at Microsoft.
“With the Win32 Driver Model, hardware developers can create drivers for Windows as easily as software developers now create Windows-based applications using Win32 APIs. The result will be a broader range of innovative, high-performance hardware for the entire Windows family.”

“Cirrus Logic is a leader in software-rich silicon solutions for multimedia, communications and storage applications,”
said George Alexy, senior vice president of marketing for Cirrus Logic.
“The Win32 Driver Model will greatly streamline our driver development efforts by allowing us to concentrate on a single set of drivers that exploit the full feature set of our chips for Windows 95 and Windows NT. For the industry in general, we think a unified driver architecture promises a new level of simplicity.”

Win32 Driver Model Architecture

The Win32 Driver Model’s architecture provides a modular class-minidriver structure. A logical class driver defines generic support for a new bus or standard device command interface. A simple minidriver is used to extend class drivers to support a specific physical device interface.

The Win32 Driver Model provides hardware separation between bus and reusable device class drivers so they can be developed independently. For USB, Microsoft is developing both a generic Win32 USB class driver and a generic Win32 device class driver for input devices, such as mice, keyboards and joysticks. The USB class driver that Microsoft is developing can be extended by a minidriver to support specific USB host controller interfaces such as OpenHCI and Universal HCI. The input device class driver can be used without modification on another bus. Hardware vendors can use a standard minidriver or easily innovate with the Win32 Driver Model by writing a minidriver for devices with new capabilities.

The Win32 Driver Model will maximize system responsiveness and throughput by providing extremely low latency services and fewer ring transitions, which interactive applications demand. All Win32 Driver Model drivers execute in Ring 0 and have access to low latency services.


Microsoft plans Win32 Driver Model support for OnNow, USB and 1394 in upcoming OEM service releases of Windows 95 later this year and in Windows NT soon thereafter. Device class support will initially include audio, input and imaging. Other device classes will be added based on market demand. A beta driver development kit (DDK) will be released at an industry Win32 Driver Model design review conference to be held at Microsoft on May 15.

Additional information on the Win32 Driver Model is available on the Microsoft Web site at

Founded in 1975, Microsoft (NASDAQ
) is the worldwide leader in software for personal computers. The company offers a wide range of products and services for business and personal use, each designed with the mission of making it easier and more enjoyable for people to take advantage of the full power of personal computing every day.

Microsoft, Win32, Windows and Windows NT are either registered trademarks or trademarks of Microsoft Corp. in the United States and/or other countries.

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