## Input/Output Device Driver Reference

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### Replacing the Parallel Port Device Driver

The parallel port device drivers contain four device headers in their data segments with the reserved device names PRN, LPT1, LPT2, and LPT3. These device names correspond to the three physical devices supported by this physical device driver. Notice that the names PRN and LPT1, although logically appearing different, correspond to the same physical device.

The parallel port device driver is replaceable. It is uninstalled by creating another parallel port device driver with the device name in the device header identical as the one listed above. It can then be reinstalled by specifying the new parallel port device driver in a DEVICE= statement in CONFIG.SYS.

Note: Installation of the files associated with the new device driver, and the addition of the corresponding DEVICE= statement in the CONFIG.SYS file, is accomplished through the DDINSTAL utility and the Device Driver Profile (DDP) for the new device driver.

When the DEVICE= statement for the new parallel port device driver is encountered in CONFIG.SYS during system initialization, the system generates a DEINSTALL request packet and sends it to the parallel port device driver. The OS/2 parallel port device driver receives the DEINSTALL request packet and releases its resources. Refer to the strategy command, " 14h / DEINSTALL" in the OS/2 Physical Device Driver Reference for more information.

If the parallel port device driver successfully releases its resources, it returns a successful completion on the Deinstallation request. When the parallel port device driver has been deinstalled, the system then generates an INSTALL request packet and sends it to the new device driver. Refer to the strategy command, "0h /INIT" in the OS/2 Physical Device Driver Reference for more information.