## Input/Output Device Driver Reference

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### Attachment Support

The ASYNC physical device driver does not provide any support for devices attached to the RS232-C port. The physical device driver provides enabling support for the RS232-C interface itself. Application programs, subsystems, and systems programs provide the support needed to use devices attached to the RS232-C port.

The ability to support a device can be determined by understanding the level of RS232-C interface enabling support the physical device driver provides, along with the characteristics of the attachment hardware in question and the required functions to be supported.

The OS/2 operating system provides a mechanism where one or more additional drivers can be installed to support specific COM ports. This feature might be required for the following reasons:

To allow an application program to support a special device not adequately supportable with this ASYNC device driver.

To allow additional COM ports (besides COM1-4 on IBM PS/2) to be supported .

To enhance the level of device driver function for a given COM port. (This might be required for certain subsystem support.)