## Physical Device Driver Reference

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### Overview

The increased user demand for additional functions in a computer system has resulted in a broader range of more sophisticated peripheral and internal system devices. The continued expansion of computer devices has in turn, stressed the already limited pool of system resources, as well as raised the complexity of detecting and configuring the devices.

Therefore, OS/2 is introducing a centralized Resource Management architecture to facilitate the coexistence and cooperation of the increasing number of device drivers. The following figure depicts the main components that comprise the OS/2 Resource Management architecture.

With the introduction of this architecture, a functional line has been drawn separating previous device driver capabilities and those of the OS/2 device drivers written to use the Resource Manager services. Device drivers written to use the Resource Manager Services are referred to as RM-aware drivers. Existing OS/2 2.x device drivers are referred to as legacy drivers . Furthermore, the definition of legacy drivers includes DOS, Windows**, and OS/2 2.x drivers.

At the center of this architecture is the Resource Manager (RESOURCE.SYS), which provides a set of C-callable services to the other RM-aware components. As denoted by the dotted box surrounding the legacy drivers in the preceding figure, an additional RM-aware component (RESERVE.SYS) has been added to report the resources used by these drivers. This reservation driver is key to maintaining an accurate map of the system resources being managed by the Resource Manager. (See RESERVE.SYS for more details on the reservation driver.)

The Resource Manager manages much more than just the system hardware resources. It also assumes centralized responsibility for coordinating all aspects of both the logical and physical views of the hardware and supporting software in the system. The logical view is defined as the standard aliases assigned to devices for application reference (such as COM1, drive A, and LPT1). The physical view is defined as the actual details of the hardware topology such as port addresses and bus type.

In order to discuss the organization of the logical and physical views provided by the Resource Manager, several concepts and terms need to be reviewed. These concepts and terms are presented next.