The following hardware defects cannot be compensated for in the physical device driver and can cause indeterminate function when used with the OS/2 physical ASYNC device driver:

Line Control Configurations

These devices are known to transmit bad data when configured for 5 data bits and 1.5 stop bits.
Receive Character Overrun Errors
These devices are known to occasionally drop received characters without posting the RECEIVE_OVERRUN error flag. Undetected data loss can result from this hardware deficiency. Application error-correction routines can be implemented to ensure accurate data transmission when these devices are being used.
Spurious Characters at Power-On
These devices can transmit a single random character at power-on. The connected device must not be expecting valid data to be received until after the physical device driver initialization routine has been run.

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