BYE5 insert for Commodore C128, external modem - 7/21/86

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; B5C8-1E.INS - BYE5 insert for Commodore C128, external modem - 7/21/86
;
;  Modifications by David Giunti,  July 20, 1986
; change MDCARCK to correct the actual PORT check
;  Note all the I/O in the C=128 is located in Bank 0, and can
;  be read and written useing the Z80's IN and OUT with 16bit
;  pointers.
;  
; Added a CMA in the MDOUTST
;
; I'm still not sure if MHZ should be 1 rather than 2, as this
; .INS could not have worked without MDCARCK
;  July 21.  This .INS will work correctly with MHZ set to 2.  If
;  you have an 80col monitor use Von Ertwine's CONFIG to set 40COL=OFF
;  as this gives a 10%+ system speed-up.  Get a copy of CCP+.LBR and use it.
;  July 26.   The TSTBAUD: routine requires that the Zero flag be set to
;  know that the  baudrate was correctly set, and MDIN2: returns it set
;  so rather than just comment out the code in the main BYE509 I'll add
;  some ugly code to set the Zero Flag manually.
;
; .INS is now very ready for final test
;      Dave Giunti  
;======================Original Header============12/12/85===========
; IMPORTANT:  When going through the options for
;    BYE5, be sure to set:
;
; MHZ  EQU  1
;
;    regardless what you think it should
;    be set for.  The modem routines built
;    into the Commodore IOS use "bit-bang-
;    ing" interrupt control and this value
;    should be used.  (All this does is
;    control the number of loops used for
;    timing purposes.)
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; 12/12/85  Written to work with BYE5 - Irv Hoff
; 07/21/86  modified version for BYE509 from work done by
;           Irv Hoff and George Peace                    - David Giunti
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; C128 data
;
PORT EQU 6
MEMRY EQU 0FD4EH
MDCTL1 EQU MEMRY+1
SNDDAT EQU MEMRY+2
RCVDAT EQU MEMRY+3
MDDCD EQU 10H ; Bit 4 to test for DCD
MDRCV EQU 01H ; Bit 0 to test for receive ready
MDSND EQU 80H ; Bit 7 to test for send
;
CBNK EQU 0FD1DH ; Address of the current bank byte
;
;
; Table of baudrate parameters
;
BD300 EQU 6 ; Divisor for 300 baud
BD1200 EQU 8 ; Divisor for 1200 bps (The Commodore
;   C128 does not support faster speeds
;   in the CP/M-128 mode)
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flag set
;
MDCARCK:
; LDA 0DD01H ; Get status
;       this should be an IN like in MDINIT below to work correctly -dag
PUSH B ; save reg
LXI B,0DD01H ; point at data port B
DB 0EDH,78H ; Input to A, pointed by BC
CMA ; Invert the value for active low
ANI MDDCD ; Check DCD for carrier from modem
POP B ; restore B reg
RET
;.....
;
;
; Disconnect and wait for an incoming call.
;
MDINIT: LXI B,0DD01H ; Dataport B
DB 0EDH,78H ; Input A (Z80 instruction)
ANI 0F9H
DB 0EDH,79H ; Output the new value, to disconnect
MVI B,20 ; 2 seconds to drop DTR

MDIN1: CALL DELAY ; 0.1 second delay
DCR B
JNZ MDIN1 ; Keep waiting until carrier drops
LXI B,0DD01H ; Reset back to normal
DB 0EDH,78H
ORI 6
DB 0EDH,79H
MVI A,1 ; Set to 8 bits, no parity
STA MEMRY ; Configure byte in BIOS
MVI B,BD300 ; Initialize to 300 baud
;.....
;
;
; Initialize the port, baudrate is now in the B-reg. find where it goes
; and put it there.
;
MDIN2: PUSH B ; Temporarily store the baudrate value
LHLD 0000H+1 ; Get BIOS address
LXI D,57 ; CP/M JMP device table
DAD D ; Index into BIOS
CALL MDIN3 ; Jumps to address now in HL
; returns with HL=char device tbl start
LXI D,PORT*8+7 ; Offset to RS232 baud rate
DAD D ; Point to RS232 baud rate byte
;   Byte now in HL
POP B ; Get the baudrate value back
MOV M,B ; Store the requested baud rate
;
;
; Have now stored desired baudrate, find the address in BIOS where the
; port will be initialized, put the correct port into the 'C' register
; and then initialize that port to baud rate just set, finished.
;
LHLD 0000H+1 ; Get BIOS address
LXI D,60 ; CP/M init address
DAD D ; Index into BIOS
MVI C,PORT ; Tell it what port to initialize
CALL MDIN3
;
xra a ; clears all bits in Acum, sets Zero flag -dag
;
;
; Jumps to HL address, performs that routine, then returns here
;
IF IMODEM
CALL IMINIT ; Initialize smartmodem
ENDIF ; IMODEM
;
RET
;...
;
;
MDIN3: PCHL ; Jump to that routine then return
;.....
;
;
; Input a character from the modem port
;
MDINP: LDA RCVDAT ; Get character
;
;
; We found there was a character, got it, but have to manually reset the
; flag to zero saying we did get the character.
;
PUSH H ; Save the current address just in case
LXI H,MDCTL1 ; Address of status byte
DB 0CBH,86H ; Reset the 0 bit of the HL status byte
POP H ; Restore the original address
RET ; Return with the character
;.....
;
;
; 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.
;
;  note that CMA is not required here because of the logical construction
MDINST: LDA MDCTL1 ; Get status
ANI MDRCV
RZ ; No character, return
;...
;
;
MDINST1:ORI 0FFH ; We have a character, clear the flag
RET
;.....
;
;
; Send a character to the modem
;
MDOUTP: STA SNDDAT ; Output the character
;
;
; Output character has been stored in the BIOS memory location, now set
; the flag showing there is a charcter ready.
;
PUSH H ; Save any current address, if needed
LXI H,MDCTL1 ; Address of the status byte
DB 0CBH,0FEH ; Set bit 7 of the HL status byte
POP H ; Get the original address back
RET ; All done
;.....
;
;
; See if the output is ready for another character
;
MDOUTST:LDA MDCTL1 ; Get the status bit
cma ; invert bits for check -dag
ANI MDSND ; Check send ready bit
RET ; If pin is high, not ready
;.....
;
;
; Renitialize the modem and hang up the phone by dropping DTR and
; leaving it inactive.
;
MDQUIT: IF IMODEM
CALL IMQUIT
ENDIF ; IMODEM
;
;
; Called by the main program after caller types BYE
;
MDSTOP: MVI B,BD300 ; Initialize to 300 baud
CALL MDIN2 ; Set to 300 baud to speed up C128
LXI B,0DD01H ; Dataport B
DB 0EDH,78H ; Input A (Z80 instruction)
ANI 0F9H ; Keep DTR set low permanently
DB 0EDH,79H ; Output the new value, to disconnect
RET
;.....
;
;
; The following routine sets the baudrte.  BYE5 asks for the maximum
; speed you have available.
;
SET2400 EQU 0
;
SETINV: MVI A,0FFH
ORA A ; Make sure the Zero flag isn't set
RET
;.....
;
;
SET300: MVI B,BD300 ; Get 300 baud parameters in 'HL'
JMP MDIN2
;

SET1200:MVI B,BD1200
JMP MDIN2
;.....
;
;
;-----------------------------------------------------------------------
; CP/M v3.0 routines
;
; Perform system or hardware dependent PRE-processing. The following
; code will be executed by the PATCH subroutine before the BIOS jump
; table is overwritten.
;
MDPREP: RET
;.....
;
;
; Perform system or hardware dependent POST-processing.
; The following code will be executed by the EXCPM routine before re-
; turning control to CP/M Plus when the BYE5 program is terminated.
;
MDPOSP: RET
;.....
;
;       end
;-----------------------------------------------------------------------
minated.
;
MDPOSP: RET
;.....
;
;       end
;--------------------------------------