OEL TTX2000 Issue 2.3: 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	downloader_not_present: Display downloader not present message for 3 seconds.
1551	OELRoutine02
170A	OELRoutine03
173D	copy_pointer_to_escape_table
1750	OELRoutine05
1756	OELRoutine06
1764	OELRoutine07
1798	OELRoutine08
17AF	OELRoutine09
17BA	OELRoutine10
17BF	OELRoutine11
185A	OELRoutine12
195F	OELRoutine13
1975	OELRoutine14
1A2B	OELRoutine15
1A5E	OELRoutine16
1A9D	OELRoutine17
1ABB	parity_error
1AC1	OELRoutine18
1AF8	OELRoutine19
1B21	hex_to_int: Convert hex digit in A to integer in B or $FF if invalid.
1B3A	OELRoutine20
1B3F	OELRoutine21
1B4D	OELRoutine22
1B50	OELRoutine23
1B7E	illegal_type: Display illegal_type_message and jump into page decode loop.
1B84	missing_operand: Display parity_error_message and jump into page decode loop.
1B8A	datatype_and_hardware: Parse Datatype and Hardware command.
1C1F	OELRoutine24
1DB2	Routine at 1DB2
1DB7	Routine at 1DB7
1DBC	Routine at 1DBC
1DC1	Routine at 1DC1
1DC4	Routine at 1DC4
1E1B	Routine at 1E1B
1E37	Routine at 1E37
1E3F	Routine at 1E3F
1E42	Routine at 1E42
1F19	Routine at 1F19
1F1F	Routine at 1F1F
1F28	Routine at 1F28
1F40	Routine at 1F40
1F50	display_error: Display error message and jump into page decode loop.
1F67	Routine at 1F67
1F7F	Routine at 1F7F
1F8D	get_hex: Get a hexadecimal keypress.