; B5C8-2.INS - BYE5 insert for Commodore C128, external modem - 8/11/86
;
;		Note, this is an insert, not an overlay.
;		It will only work with BYE510 or higher.
;		When going through the options for
;		BYE5, set the clock speed:
;
;			  MHZ  EQU  1
;
;		The modem routines built into the Com-
;		modore IOS use "bit-banging" interrupt
;		control and this value should be used.
;		(All this does is control the number of
;		loops used for timing purposes.)
;
;-----------------------------------------------------------------------
; TO INSTALL:
;
; You will need the following files from BYE5nn.LBR to properly imple-
; ment BYE5 on your C128 which uses CP/M 3.0:
;
;     BYE5nn.AQM   - The BYE5 source file for CP/M 2 or CP/M 3
;     B5-CPM3.AQM  - CP/M Plus program renamed to BYE.COM during install
;     B5-DRIV3.AQM - BYE5 RSX driver program called internally by BYE
;		     to initialize the CP/M Plus RSX
;
; You will need the following file from B5-CLOCK.LBR if you want to use
; the clock support provided in BYE5:
;
;     B5C-CPM3.IQS - CP/M Plus clock insert
;
; Configuration information for BYE5 is available in BYE5.DQC (from
; BYE5nn.LBR).	Additional CP/M Plus-specific information and generation
; instructions are in B5-CPM3.DQC (also from BYE5nn.LBR).
;
;						- notes by George Peace
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; 07/21/86  Modified version for BYE510.  Changed MRCARCK to correct the
;	    actual PORT check.	Added a CMA in MDOUTST.  Reset Zero-flag
;	    in MDIN2: for baud rate change.	- David Giunti
;
; 12/12/85  Original version for BYE5		- Irv Hoff
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; 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:
	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		; Sets Zero flag
;
;
; 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.
;
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
	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
;-----------------------------------------------------------------------

.
