## Input/Output Device Driver Reference

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### OS/2 PCMCIA Environment

There are three separate PCMCIA client environments in the OS/2 operating system: the DOS environment, WIN-OS/2 environment, and OS/2 environment. Each of these client environments has a separate Card Services interface binding (or protocol) that encapsulates the Card Service functions into the native environment's characteristics. Although the OS/2 operating system supports these three application environments, it currently does not support the PCMCIA client interfaces in all environments.

The responsibilities and restrictions of providing support for these client environments is summarized as follows:

OS/2 Card Services is responsible for providing the client environment interfaces.

Currently this support is limited to the native OS/2 device-driver environment for OS/2 physical device drivers. The OS/2 client environment support is provided by the OS/2 Card Services and the physical device driver contained in the file named PCMCIA.SYS. The interface bindings for this support are defined in Client Interfaces.

The architecture is designed such that the PCMCIA software components mask the hardware details from the OS/2 application environments. The concept of a PCMCIA-aware application does not apply in the OS/2 operating system.

The DOS client environment is not supported. This means that the DOS PCMCIA interfaces, INT 1Ah functions in the range of 80h - AFh, are intercepted and rejected with the Carry flag set (value = 1). The DOS client environment support is provided by the OS/2 Card Services and virtual device driver contained in the file named VPCMCIA.SYS.

The WIN-OS/2 client environment is not supported.

At this time, the industry has not defined an interface binding for the WIN -OS/2 client environment; therefore, there are no OS/2 files provided for this environment.

OS/2 PCMCIA clients are responsible for providing device-specific support in the desired application environments.

OS/2 PCMCIA clients can be written as stand-alone physical device drivers or as physical/virtual device driver pairs. If the desired client device support is limited to OS/2 application environments, the client can be a single physical device driver. If the desired application environments include a DOS or WIN-OS/2 environment, or both, then a virtual device driver also must be provided to emulate the device characteristics in those environments.