Volex TTX2000 S Issue 1.2: Routine at 1BD8

1BD8: start_telesoftware: Load the telesoftware index on Channel 4 page 460.

Used by the routine at telesoftware_jump.
start_telesoftware	1BD8	CALL clear_page_buffer	Clear page display buffer.
	1BDB	LD A,$07	Set control_register to $07 and output to control register to page in ROM (also enables AFC and switches to channel 4).
	1BDD	OUT ($7F),A
	1BDF	LD (control_register),A
	1BE2	LD HL,(page_display_buffer_pointer)	Load page_display_buffer_pointer into HL.
	1BE5	LD A,$50	Write 'P' character to page display buffer.
	1BE7	LD (HL),A
	1BE8	INC HL
	1BE9	LD A,$04	Set magazine_number to 4.
	1BEB	LD (magazine_number),A	Set magazine_number to 4.
	1BEE	OR $30	Convert to '4' character and write to next column of page display buffer.
	1BF0	LD (HL),A
	1BF1	INC HL
	1BF2	LD A,$06	Set page_tens to 6 and write '6' character to page display buffer.
	1BF4	LD (page_tens),A
	1BF7	OR $30
	1BF9	LD (HL),A
	1BFA	INC HL
	1BFB	LD A,$00	Set page_units to 0 and write '0' character to page display buffer.
	1BFD	LD (page_units),A
	1C00	OR $30
	1C02	LD (HL),A
	1C03	XOR A	Clear subpage_search_flag
	1C04	LD (subpage_search_flag),A	Clear subpage_search_flag
	1C07	CALL display_header_row	Update the header row display.
	1C0A	LD HL,telesoftware_main	Set telesoftware_pointer to telesoftware_main and return.
	1C0D	LD (telesoftware_pointer),HL
	1C10	RET