; B5NH-1.INS - BYE5 insert for North Star Horizon computers - 10/15/85 ; ; 8251A and no baudrate generator ; ; Pin 8 (DCD) from the modem must be connected to the USART's DSR input, ; normally Pin 6. ; ; Note: This is an insert, not an overlay. ; ; ; = = = = = = = = = = = = = = = = = = ; ; 10/15/85 Original version for BYE5 - Irv Hoff ; ; = = = = = = = = = = = = = = = = = = ; ; ;The following define the port address to use ; PORT EQU 4H ; Data port MDCTL1 EQU PORT+1 ; Status/control port ; BPORT EQU MDCTL1 ; Baud rate port=8251 control ; ; ;----------------------------------------------------------------------- ; ; ; See if we still have a carrier - if not, return with the zero flag set ; MDCARCK:IN MDCTL1 ; Get status ANI 80H ; Check DSR bit for a carrier RET ;..... ; ; ; Disconnect and wait for an incoming call ; MDINIT: MVI A,10H ; Clear DTR OUT MDCTL1 ; Causing hangup PUSH B ; Preserve in case we need it MVI B,20 ; 2 second delay ; OFFTI: CALL DELAY ; 0.1 second delay DCR B JNZ OFFTI ; Keep looping until finnished POP B ; Restore BC MVI A,17H ; Assert DTR so that modem OUT MDCTL1 ; Can answer phone XCHG ; Small delay XCHG ; Small delay ; IF IMODEM CALL IMINIT ENDIF ; IMODEM ; RET ;..... ; ; ; Input a character from the modem port ; MDINP: IN PORT ; Get character RET ;..... ; ; ; Check the status to see if a character is available. If not, return ; with the zero flag set. If yes, use 0FFH to clear the flag. ; MDINST: IN MDCTL1 ; Get status ANI 02H ; Check the receive ready bit RZ ; Return if none ORI 0FFH ; We have a character RET ;..... ; ; ; Send a character to the modem ; MDOUTP: OUT PORT ; Send it RET ;..... ; ; ; See if the output is ready for another character ; MDOUTST:IN MDCTL1 ANI 01H ; Check the transmit ready bit RET ;..... ; ; ; Reinitialize the modem and hang up the phone by dropping DTR and ; leaving it inactive. ; MDQUIT: IF IMODEM CALL IMQUIT ; Tell modem to quit ENDIF ; IMODEM ; ; ; Called by the main program after caller types BYE ; MDSTOP: MVI A,10H ; Turn off DTR OUT MDCTL1 RET ;..... ; ; ; The following routine sets the baudrate. BYE5 asks for the maximum ; speed you have available. ; SET2400 EQU $ ; Only supports 300/1200 ; SETINV: ORI 0FFH ; Make sure zero flag not set RET ;..... ; ; SET300: MVI B,BD300 JMP SETBAUD ; SET1200:MVI B,BD1200 ; SETBAUD:MVI A,47H ; Reset, enable Rx, DTR, Tx OUT MDCTL1 ; Rx,Tx enabled XCHG ; Small delay XCHG ; Small delay MOV A,B ; Recover Baud Rate Word OUT BPORT XCHG ; Small delay XCHG ; Small delay MVI A,17H ; ERR reset, DTR, Rx, Tx all on OUT MDCTL1 XCHG ; Small delay XCHG ; Small delay XRA A ; Say rate OK RET ;..... ; ; ; Values to switch the 8251 between x16 and x64 300 or 1200 bps ; BD300 EQU 4FH ; 300 baud BD1200 EQU 4EH ; 1200 bps ; ; ; end ;------------------------------------------------------