Channel Initialization After selecting the desired operating parameters (i.e., parity, word length, etc.), this information must be stored into the channel parameter register. The channel may now be initialized with the "Initialize Channel" command. The channel is now ready to transmit or receive. If any of the interrupt enable bits were set with the command, and their associate conditions true, an interrupt would be generated at this point. At any time, a No-Op command may be issued to effect the interrupt enable bits only. Channel Transmit Operation To transmit a block of data, the proper procedure is as follows:
Test if last command still pending or loop if true> Test if transmitter ready or loop if false> Set address and byte count Issue transmit command Increment "New Command Register" Exit Channel TTY Receive Operation To receive a character in TTY mode, the proper procedure is as follows:
Test if last command still pending or loop if true> Test if receive character available or loop if false> Read status (test for errors) If Error Issue Reset Error command Increment "New Command Register" Exit Else Read character from TTY register Issue Receiver Ack command Increment "New Command Register" Exit Channel Ring Buffered Receive Operation To receive a character in Ring Bufferred Receive mode, the proper procedure is as follows: Test if last command still pending or loop if true> 5-29