Appendix A System Interface Description
3. Shared Operation
In shared operation the interface buffer capacity is reduced by 256 bytes.
After
If a byte is first recognized by the serial interface the parallel interface is imme- diately disabled by the BUSY signal. The serial interface is now active and will operate, using the installed protocols.
If a byte is first recognized by the parallel interface either the DTR signal of the serial interface is set to OFF or XOFF is sent, depending on the protocol.
If the serial interface starts to receive data while the parallel interface is active, it is possible to receive 256 bytes of serial data. Any additional serial data will be lost.
When the interface buffer is completely empty of serial data, and no new data has been received by the serial interface for more than 10 seconds, both interfaces are available for data transfer again.
When the interface buffer is completely empty of parallel data and no data has been received by the parallel interface for more than 60 seconds, the 256 bytes of serial data will be processed. Afterwards, both interfaces are available for data transfer again.
