;	CROSSTALK I/O DRIVERS FOR HORIZON COMPUTER ON PRINTER PORT

status	equ	5			; status port address
data	equ	4			; data port address

rrf	equ	2			; mask for receiver reg. full
tbe	equ	1			; mask for transmitter buffer empty

	org	100h
	jmp	200h			; jump into CROSSTALK

	org	110h
stat:	in	status			; get port status
	ani	rrf			; mask for char.
	ret

	org	120h
sin:	in	status			; get port status
	ani	rrf			; mask for char.
	jz	sin			; loop until we have a character
	in	data			; get the char.
	ret

	org	130h
sout:	push	psw			; save the character on the stack
sout1:	in	status			; get the port status
	ani	tbe			; mask for buffer empty
	jz	sout1			; loop until it is
	pop	psw			; get the character back
	out	data			; send it to the modem port
	ret				; and back to CROSSTALK

	org	140h
carr:	nop ! nop ! ret			; dummy carrier routine

	end	100h