DESKTOP x1k12
                                ͻ
                                     MC6850      
                                 bit assignments 
                                ͼ
                                 Motorola Corporation 6850
                                 Asynchronous Communication Interface Adaptator
              Ŀ
               Status Register     b15=interrupt requested
                                       0:no
                                       1:yes
                                   b13=overrun error
                                       0:no
                                       1:yes
                                    b9=transmit register empty
                                       0:no
                                       1:yes
                                    b8=receive register full
                                       0:no
                                       1:yes
              
             Ŀ
              Control Register     b15=interrupt when receive register full
                                       0:no
                                       1:yes
                                   b13=interrupt when transmit register empty
                                       0:no
                                       1:yes
                                 b9-b8=11:reset
             
             Ŀ
              Receive Register  b15-b8=[b7-b0]=receive register
             
            Ŀ
             Transmit Register  b15-b8=[b7-b0]=transmit register
            
