+HRSFB := $57
+
+; RS232T
+; b0-b3 : speed
+; 1111 => 19200 bps (please note that telestrat can't handle this speed without stopping all IRQ except ACIA's one)
+; 1100 => 9600 bps (default from telemon)
+; 1110 => 4800 bps
+; 1010 => 2400 bps
+; 1000 => 1200 bps
+; 0111 => 600 bps
+; 0110 => 300 bps
+; 0101 => 150 bps
+; 0010 => 75 bps
+
+; b4 : 0 external clock, 1 internal clock
+; b6-b5 : 00 8 bits
+; 01 7 bits
+; 10 6 bits
+; 11 5 bits
+; b7 : 0 a stop
+
+RS232T := $59
+
+; RS232C
+; b0-b3 : 0
+; b4 : 1 if echo
+; b5 : 1 if parity
+; b7-b6 : 00 in/out parity odd
+; : 01 on/out parity even
+; : 10 parity sent, answer not tested
+; : 11 SPACE SENT, reception not tested
+
+RS232C := $5A