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; B3OS-2.INS - Osborne OS-1 insert for BYE3 - 07/30/85
;
;			6850 ACIA
;
; Note:  This is an insert, not an overlay.  If your OS-1 does not have
;	 have the hardware mod to support DTR, (shown below) then set
;	 the NODTR option in BYE3 to "YES".  Also set:
;
;		    IMODEM   EQU   YES
;
;
; MAIN LOGIC BOARD TRACE CUTS:
; --------------------------
; Solder Side:
;
; Cut  trace  running  from pin 5 to pin 6 on inner  row  of  pads
; used in mounting the	RS-232	female serial connector at the front
; of  main logic board.  Pin 1 is pad with wide ground trace.
;
; Component side:
;
; Cut trace from pin 5 of UC4 (6850) to R20 (10K ohm).
; Cut trace that runs between pins 3 and 4 of UC4 (6850).
;
;
; PART ADDITIONS:
; --------------
; Solder side:
;
; Add jumper from pin 1 of UE3 (MC1458) to pin 5 of inner row of
;    RS-232 serial port pads.  Pin 1 has wide ground trace.
; Add jumper from pin 3 to pin 5 of UE3 (MC1458).
; Add jumper from pin 10 of UD4 (LM3400) to pin 5 of UC1 (74LS08).
; Add jumper from pin 4 of UC1 (74LS08) to pin 1 of UE20 (74LS04).
; Add jumper from pin 6 of UC1 (74LS08) to pin 5 of UA11 (74S04).
; Add jumper from pin 6 of UA11 (74S04) to pin 19 of UC15 (6821).
;
; Component side or solder side (whichever side you feel more
; comfortable using for mounting components):
;
; Add 10K ohm resistor from Vcc (+5 volts) to pin 2 of UE3 (MC1458).
; Add 220 ohm resistor from pin 5 of UC4 (6850) to pin 2 of UE3 (MC1458).
; Add 1k  ohm resistor from pin 19 of UC15 (6821) to Vcc (+5 volts).
;
; NEW RS-232 MODEM CABLE:
; ----------------------
;
;	  OCC-1 		       MODEM
;
;	 2    RXD		      3    RXD
;	 3    TXD		      2    TXD
;	 4    DCD (new function)      8    DCD
;	 5    DTR (new function)     20    DTR
;	 7    GND		      7    GND
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
; 07/30/85  Restored to original format			- pst
; 07/17/85  Revised for use with BYE3			- Kevin Murphy
;
; =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =   =
;
HARDMOD	EQU	YES	; YES, if hardware mods have been done to Osborne
			;      O-1 to support DTR and modified DCD.
			; NO,  if the O-1 is standard (no mods).  If NO
			;      you must be using a Hayes Compatible modem and
			;      set NODTR to yes in the main equates.

;
STATM	EQU	02A00H		; Status memory location
DATA	EQU	02A01H		; Data memory location
CDATA	EQU	02C02H		; Video PIA data register
CSTAT	EQU	02C03H		; Video PIA status register
;
	 IF	HARDMOD
DCD	EQU	40H		; Data carrier detect
	 ENDIF
;
	 IF	NOT HARDMOD
DCD	EQU	04H		; Data carrier detect
	 ENDIF
;
RDAV	EQU	11111110B	; Reversed DAV
DAV	EQU	00000001B	; Normal DAV
;
RTBMT	EQU	11111101B	; Reversed TBMT
TBMT	EQU	00000010B	; Normal TBMT
;
BD300	EQU	22		; 300 baud
BD1200	EQU	21		; 1200 baud
;
;-----------------------------------------------------------------------
;
; See if we still have a carrier - if not, return with the zero flag set
;
MDCARCK:
	 IF	HARDMOD
	DI		; Disable interrupts
	OUT	0
	LDA	CSTAT	; Read video PIA status register
	OUT	1
	EI
	 ENDIF
;
	 IF	NOT HARDMOD
	CALL	BNKINS	; Get modem status
	PUSH	PSW	; Save it
	ANI	DCD	; If carrier is then reset DCD
	CNZ	MDINP
	POP	PSW
	 ENDIF
;
	CMA		; Comp register, bit set with LOSS of carrier
	ANI	DCD	; Mask out everything but carrier LOSS bit (cb2)
	RZ
	ORI	255
	RET
;
; Disconnect and wait for an incoming call
;
MDINIT:	MVI	A,57H		; Hangup if we can
	CALL	BNKOUTS
;
	DI
	OUT	0
	LDA	CDATA		; Read video PIA data register
	OUT	1		; Reset for future loss of carrier
	EI
;
	PUSH	B
	MVI	B,20		; Wait 2 seconds for modem to hangup
OFFTI:	CALL	DELAY
	DCR	B
	JNZ	OFFTI
;
	LDA	WRKBAUD		; Modem port reset (enable DTR line)
	ANI	0BFH		; Enable DTR
	CALL	BNKOUTS
;
	 IF	IMODEM
	CALL	IMINIT		; Initialize intelligent modem
	 ENDIF
;
	DI
	OUT	0
	LDA	CDATA		; Read video PIA data register
	OUT	1		; Reset for future loss of carrier
	EI
;
	RET
;
; Input a character from the modem port
;
MDINP:	CALL	BNKIND	; Input data from the outside
	PUSH	PSW	; Save the character
	LDA	SSTAT	; Load mirror ACIA status register
	ANI	RDAV	; Mask the DAV bit (reset DAV bit in mirror
			;   			status register)
	STA	SSTAT	; Save our mutant status register to ram
	POP	PSW	; Get the character back
	RET		; Return to sender
;
; 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:	PUSH	B
	LDA	SSTAT	; Load ACIA mirror status register
			; From last status read operation
	MOV	B,A
	CALL	BNKINS	; Input present ACIA status register
	ORA	B	; Perform an OR operation on both former
			;   as well as present acia registers
	STA	SSTAT	; Save both ACIA register states
	POP	B
	ANI	DAV	; Mask DAV bit
	RZ
	ORI	255
	RET
;
; Send a character to the modem
;
MDOUTP:	CALL	BNKOUTD	; Send the data character modem
	LDA	SSTAT	; Load the clone register
	ANI	RTBMT	; Mask the TBMT bit
	STA	SSTAT	; Save the doppelganger register
	RET		; Return to sender
;
; See if the output is ready for another character
;
MDOUTST:PUSH	B
	CALL	BNKINS	; Get present ACIA status register
	MOV	B,A	; Move it to 'B' register
	LDA	SSTAT	; Get mirror ACIA status register
	ORA	B	; Perform an OR on present and mirror registers
	POP	B
	STA	SSTAT	; Save the past and present status registers
	ANI	TBMT
	RZ
	ORI	255
	RET
;
; Called by the main program after caller types BYE
;
MDQUIT:
	 IF	IMODEM
	CALL	IMQUIT
	 ENDIF
;
; Called by the main program after caller types BYE
;
MDSTOP:	MVI	A,57H
	CALL	BNKOUTS	; hangup modem
	RET
;
BNKINS:	DI		; Disable interrupts
	OUT	0	; Switch banks to shadow memory bank
	LDA	STATM	; Read status register ram location
	OUT	1	; Switch banks back to progaram memory bank
	EI		; Reenable interrupts
	RET		; Go home
;
BNKIND:	DI		; Disable interrupts
	OUT	0	; Switch banks to shadow memory bank
	LDA	DATA	; Read data register RAM location
	OUT	1	; Switch banks back to program memory bank
	EI		; Reenable interrupts
	RET		; Go home
;
BNKOUTS:DI		; Disable interrupts
	OUT	0	; Switch banks to shadow memory bank
	STA	STATM	; Send data to control register ram location
	OUT	1	; Switch banks to program memory bank
	EI		; Reenable interrupts
	RET		; Go home
;
BNKOUTD:DI		; Disable interrupts
	OUT	0	; Switch banks to shadow memory bank
	STA	DATA	; Send data to control register ram location
	OUT	1	; Switch banks to program memory bank
	EI		; Reenable interrupts
	RET		; Go home
;
; The following routine sets the baudrate.  BYE3 asks for the maximum
; speed you have available.
;
SET300:	MVI	A,BD300		; Set 300 baud
	JMP	SETBAUD
;
SET1200:MVI	A,BD1200	; Set 1200 baud
;
SETBAUD:CALL	BNKOUTS
	STA	WRKBAUD		; Save incoming baud rate
	XRA	A		; Show baudrate was ok
	RET
;
SET2400:ORI	255	; Osborne can't handle 2400 baud
	RET
;
;----------------------------------------------------------------
;
WRKBAUD:DB	16H	; [*] OCC1 ++
SSTAT:	DB	0	; RAM flag location for ACIA status register.
			;   This is due to ACIA not keeping track of its
			;   status register when data is going in both
			;   directions i.e., data being sent out during
			;   a display listing, and the remote user wants
			;   to suspend screen display or abort listing
			;   by generating a ^S or ^K or any other con-
			;   trol character.
;
;	end
;-----------------------------------------------------------------------
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