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; B3AP-2.INS - APPLE ][ with Mountain CPS Serial Card - 07/30/85
;
;		2651 with internal baudrate generator
;
;	       NOTE: This is an insert, not an overlay.
;
; WARNING:  Carrier detect (DCD) from the modem must go to DSR input on
;	    the 2651 to provide proper operation for both autodialing
;	    and autoreceiving.	If you use the DCD input, it requires
;	    voltage (normally unavailable) during dialing to allow
;	    result codes to be used.
;
;	To build "a better modem cable", on the apple side of the cable,
;	hook the following pins together:
;		5, 8, 20	- this will force CTS and DCD high when
;				  DTR is on.
;		6		- tie the real DCD (pin 8 on the modem)
;				  to this pin.
;
;    	This program assumes you use the DSR pin (80H) to check carrier
;	from the modem.
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; 07/30/85  Restored original format			- pst
; 07/24/85  Fixed minor bug with 2400 baud setting	- pst
; 01/20/84  Created overlay using BY2-2651.ASM		- Norman Beeler
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; Define the CPS card slot you are using (normally 1 or 2)
;
SLOT	EQU	2		; CPM card slot
;
;=======================================================================
;
; Modem port equates
;
DPORT	EQU	0E0FAH+SLOT*100H ; Modem data port
SPORT	EQU	0E0FBH+SLOT*100H ; Modem status port
XPORT	EQU	0E0FEH+SLOT*100H ; Modem swap port
;
; Status port equates
;
TBMT	EQU	00000001B	; Transmit buffer empty
DAV	EQU	00000010B	; Data available
DCD	EQU	10000000B	; Data carrier detect
;
; Mode port equates
;
EBASE	EQU	30H		; Mode register 2 base
B300	EQU	EBASE+5		; 300 baud
B1200	EQU	EBASE+7		; 1200 bps
B2400	EQU	EBASE+10	; 2400 bps
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flag set
;
MDCARCK:LDA	SPORT		; Read port
	ANI	DCD		; Check DSR for carrier (do not use DCD)
	RZ
	ORI	255
	RET
;
; Disconnect and wait for an incoming call
;
MDINIT:	MVI	A,80H		; Open CPS command register
	STA	XPORT		; By storing 80H in XPORT
	MVI	A,15H		; Turn DTR off, modem will quit
	STA	SPORT
	MVI	B,20		; 2 seconds to drop any carrier
;
MDINIT1:CALL	DELAY		; .1 second delay
	DCR	B
	JNZ	MDINIT1
	MVI	A,17H		; With DTR on, modem accepts commands
	STA	SPORT
	XRA	A		; Close the command port
	STA	XPORT		; By storing 0 in XPORT
;
	 IF	IMODEM
	CALL	IMINIT		; Initialize smartmodem
	 ENDIF			; IMODEM
;
	RET
;
; Input a character from the modem port
;
MDINP:	LDA	DPORT		; 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:	LDA	SPORT		; Read port
	ANI	DAV		; Check receive ready bit
	RZ			; Nope, nothing there
	ORI	255		; We got something...
	RET
;
; Send a character to the modem
;
MDOUTP:	STA	DPORT		; Send it
	RET
;
; See if the output is ready for another character
;
MDOUTST:LDA	SPORT		; Read port
	ANI	TBMT		; Check transmit ready bit
	RZ
	ORI	255
	RET
;
; Reinitialize the modem and hang up the phone by dropping DTR and
; leaving it inactive.
;
MDQUIT:	 IF	IMODEM
	CALL	IMQUIT		; Initialize modem to default settings
	 ENDIF			; IF IMODEM
;
;
; Called by the main program after caller types BYE
;
MDSTOP:	MVI	A,80H		; Open CPS command register
	STA	XPORT		; By storing 80H in XPORT
	XRA	A		; Turn DTR off, modem will quit
	STA	SPORT
	CALL	DELAY		; Let it stabilize
	RET
;
; The following routine sets the baudrate.  BYE3 asks for the maximum
; speed you have available.
;
SET300:	CALL	BSETUP
	MVI	A,B300
	JMP	FSETUP
;
SET1200:CALL	BSETUP
	MVI	A,B1200
	JMP	FSETUP
;
SET2400:CALL	BSETUP
	MVI	A,B2400
	JMP	FSETUP
;
BSETUP:	MVI	A,80H
	STA	XPORT
	MVI	A,37H		; Initialize the serial chip
	STA	SPORT		; By storing 37H in SPORT
	MVI	A,4EH		; 1 stop, 8 bits, no parity
	STA	DPORT
	XRA	A
	RET
;
FSETUP:	STA	DPORT
	XRA	A
	STA	XPORT		; Close command port by storing 0
	RET
;			       end
;-----------------------------------------------------------------------
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