Volex TTX2000 S Issue 1.2: Routine at 1B8A

1B8A: wait_for_page: Wait up to 2 minutes for page to load (or enter key pressed).


wait_for_page	1B8A	XOR A	Clear page_ready_flag and ignore_packets_flag.
	1B8B	LD (page_ready_flag),A
	1B8E	LD (ignore_packets_flag),A
	1B91	LD DE,$0BB8	Set DE to 3000 as a loop counter.
wait_for_page_0	1B94	LD A,(page_ready_flag)	If page_ready_flag is set then set ignore_packets_flag and return 0.
	1B97	OR A
	1B98	JR Z,wait_for_page_1
	1B9A	LD (ignore_packets_flag),A
	1B9D	XOR A
	1B9E	RET
wait_for_page_1	1B9F	LD BC,$BFFE	Else if enter key is pressed return 1.
	1BA2	IN A,(C)
	1BA4	RRCA
	1BA5	JR C,wait_for_page_2
	1BA7	LD A,$01
	1BA9	RET
wait_for_page_2	1BAA	PUSH DE	Else preserve DE.
	1BAB	CALL data_to_header_row	Copy header row from page receive buffer into page display buffer.
	1BAE	CALL display_header_row	Display row 0 of page display buffer (this usually takes more than 1 frame if there are control codes).
	1BB1	POP DE	Restore DE.
	1BB2	EI	Wait for next video frame.
	1BB3	HALT
	1BB4	DI
	1BB5	DEC DE	Decrement DE and loop back to wait_for_page_0 until DE equals zero (wait for up to two minutes) then return 2.
	1BB6	LD A,D
	1BB7	OR E
	1BB8	JR NZ,wait_for_page_0
	1BBA	LD A,$02
	1BBC	RET