Volex TTX2000 S Issue 1.2: Routines

Address	Description
0000	START: ROM reset
000A	ignore_subcode: Prepare to execute page_found.
0012	inhibit_display_clear: Clear inhibit_display and set exit_pointer to backup_exit_pointer.
0038	MASK_INT: IM 1 maskable interrupt service routine
0066	NMI: Non-Maskable interrupt vector
0069	NMI_ISR: Non-Maskable Interrupt service routine
0280	hamming_decode_hl: Hamming 8/4 decode the byte at address in HL and return it in B.
028B	set_hardware_counter: Reads a byte from the decoder's SRAM but doesn't retain it. This sets an internal 4 bit counter to bits 6-9 of the read address.
0292	decode_magazine_number: Get the magazine number from the Magazine Row Address Group.
029D	decode_packet_number: Get the packet address from the Magazine Row Address Group.
02B7	store_packet_30: Copy packet to row 29 of page receive buffer.
02CA	init_memory: Main initialization routine.
0328	init_variables: Initialize BASIC system variables in a similar way to the BASIC ROM 'NEW' routine and initialize own variables in printer buffer.
043A	NMI_VECTOR: Jump to NMI service routine (Copied to NMI_JUMP).
043D	init_48k: Initialise pointers for 48k systems.
046D	init_16k: Initialise pointers for 16k systems
0640	display_menu: Display the main menu and wait for enter key to be pressed.
06A6	print_character: Print character to the screen
073B	print_half_row: Print 4 pixel rows of character bitmap over 8 pixel rows of screen (double height).
074C	print_double_column_0: Write 4 pixel rows of double height character data over 8 pixel rows at column that is a multiple of 4.
0766	print_double_column_1: Write 4 pixel rows of double height character data over 8 pixel rows at column that is 1 greater than a multiple of 4.
0780	print_double_column_2: Write 4 pixel rows of double height character data over 8 pixel rows at column that is 2 greater than a multiple of 4.
079A	print_double_column_3: Write 4 pixel rows of double height character data over 8 pixel rows at column that is 3 greater than a multiple of 4.
07B4	print_normal: Print 8 pixel rows of font data (a normal height character).
07C5	print_column_0: Write character data at column that is a multiple of 4.
07D3	print_column_1: Write character data at column that is 1 greater than a multiple of 4.
07F2	print_column_2: Write character data at column that is 2 greater than a multiple of 4.
080F	print_column_3: Write character data at column that is 3 greater than a multiple of 4.
081B	screen_address: Calculate the address in screen RAM of the second byte of character row in A.
084D	set_attrs: Set screen attributes corresponding to screen address in character screen address variable to value in temp_attr.
08B0	clear_screen: Clear display bitmap and attributes.
08C4	clear_page_buffer: Clear page display buffer to spaces.
08DF	clear_receive_rows: Clear all rows except header in page receive buffer.
08F7	decode_row: Decode row of teletext data and render it to the screen.
0998	alpha_colour_code: Alphanumeric colour control code.
09AA	normal_code: Handle normal size control code.
09B6	double_code: Handle double height control code.
09C9	mosaics_colour_code: Handle a mosaics colour code.
09EB	conceal_code: Handle conceal code.
09FB	contiguous_code: Handle contiguous mosaics cotrol code.
0A02	separated_code: Handle separated mosaics cotrol code.
0A17	black_background_code: Clear paper colour bits of temp_attr.
0A22	new_background_code: Copy ink colour bits of temp_attr to paper colour bits.
0A37	hold_mosaics_code: Handle hold mosaics code.
0A4C	Release_mosaics_code: Handle release mosaics code.
0A52	code_set_at: Display character.
0AB8	translate_colour: Translate an alphanumeric colour code to spectrum attribute colour.
0ADC	set_character_pointer: Set character_pointer to start of current row in page display buffer.
0AFA	wait_and_decode_page: Wait for page_ready_flag, and check for key presses.
0B46	decode_page: Decode and render 24 rows.
0E60	init_mosaics: Initialize font data for contiguous and separated mosaic character sets.
0EC9	generate_mosaics: Generate font data for contiguous mosaic with the character code in B at the address in HL.
0EFD	copy_blast_through: Copy blast through alphanumerics font data.
0F06	Copy 32 contiguous mosaic characters from address in HL to address in DE, separating the columns.
0F11	write_top_sixels: Write bitmap in D to three rows of font data.
0F18	set_right_bits: Set right half of mosaic bits.
0F1F	get_keypress.
0F34	scan_keyboard: Loop through keyboard rows to detect a keypress and return return key code.
0FA2	detect_any_key: Detect if any key is pressed.
0FB2	handle_keypress: Handle a keypress while in teletext mode.
0FFB	toggle_bright: Toggle bright flag.
1009	exit_routine: Relocatable exit to BASIC routine.
1034	no_printer: Break out of printer loop gracefully.
1038	print: Printer routine for Sinclair ZX Printer or Alphacom 32.
109C	enter_page: Get valid page number and display digits in row 0.
10EB	enter_page_and_clear: Get valid page number then clear the page buffer.
10F0	enter_subcode_and_clear: Get valid page subcode then clear the page buffer.
1155	get_dec_digit: Wait for a keypress in the range 0-9.
1163	select_channel: Channel selection and tuning display.
11C8	hold_page: Pressed H to hold page.
1220	toggle_reveal.
122B	data_to_header_row: Copy header row data from recieve buffer to page display buffer.
1243	display_header_row: Decode and display the header row.
1257	copy_page_data: Copy received page data into page display buffer.
1277	clear_page_number: Copy page number display to number_display_buffer and clear to spaces.
1293	restore_number: Copy number_display_buffer into page number display.
12B1	save_routine: Relocatable save page routine.
13B4	init_hamming_table: Create 256 byte look up table of Hamming 8/4 decoded bytes.
1481	store_hamming_nibble: Read the four data bits from hamming coded byte into address in HL
14AA	store_hamming_error
14AE	correct_and_store_nibble: Correct a single bit error at bit position in C.
14BB	warm_start_routine: Relocatable "warm start" from BASIC routine.
14D5	clear_header: Clear page header to spaces.
14F0	copy string in HL to page header
1512	pause_3s: Pause for 3 seconds
151C	get_hex_digit: Wait for a keypress in the range 0-9 or A-F.
1532	download_complete: All telesoftware blocks downloaded.
1538	parse_download: Determine what to do with telesoftware download based on the footer.
1582	execute_basic_stop: Setup VARS, and E-LINE and prepare to execute STOP.
15A2	execute_basic_continue: Setup VARS, E-LINE, and OLDPPC, and prepare to execute CONTINUE.
15CD	setup_vars_eline: setup VARS and E-LINE.
15E9	execute_code: Relocate and execute jump to machine code routine.
15F7	page_out_to_code: Relocatable page out ROM and execute machine code routine.
1600	return_to_STOP: Prepare to execute STOP with no variables.
1619	load_next_nibbles: Load next four low nibbles into address in HL.
1623	execute_basic: Relocate and execute initialize BASIC routine.
1632	page_out_to_basic: Relocatable initialize BASIC routine.
185A	check_page: Telesoftware page checksum.
18ED	download_data: Download data from page into memory specified in nibbles at row 23, column 8.
1938	block_downloaded: See if there are undownloaded blocks remaining.
1954	load_nibbles: Read low nibble of four bytes from address in DE to word at address in HL.
1966	write_header_message: Copy up to 16 bytes from address in DE to row 0 in page display buffer.
1B8A	wait_for_page: Wait up to 2 minutes for page to load (or enter key pressed).
1BBD	clear_header_start: Clear 16 characters of header to spaces.
1BD8	start_telesoftware: Load the telesoftware index on Channel 4 page 460.
1C1F	telesoftware_jump.
1C22	telesoftware_main: Main telesoftware interface loop.
1C86	display_message: Display telesoftware error and prompt for input.
1D15	check_footer: Check row 23 of recieved page for telesoftware footer.
1D66	buffers_in_screen: Reposition the page receive buffer at $4840 and the page display buffer at $5000 (within screen RAM).
1D9D	border_flash: Flash border to colour in A for 300ms.
1F8D	get_hex: Get a hexadecimal keypress.
1F98	telesoftware_number: Input page number for telesoftware page search.