OEL TTX2000 Issue 2.3: Memory map

Page	Byte	Address	Description
0	0	0000	START: ROM reset
0	4	0004	Unused
0	10	000A	ignore_subcode: Prepare to execute page_found.
0	18	0012	inhibit_display_clear: Clear inhibit_display and set exit_pointer to backup_exit_pointer.
0	31	001F	Unused
0	56	0038	MASK_INT: IM 1 maskable interrupt service routine
0	66	0042	Unused
0	102	0066	NMI: Non-Maskable interrupt vector
0	105	0069	NMI_ISR: Non-Maskable Interrupt service routine
2	122	027A	Unused
2	128	0280	hamming_decode_hl: Hamming 8/4 decode the byte at address in HL and return it in B.
2	139	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.
2	146	0292	decode_magazine_number: Get the magazine number from the Magazine Row Address Group.
2	157	029D	decode_packet_number: Get the packet address from the Magazine Row Address Group.
2	183	02B7	store_packet_30: Copy packet to row 29 of page receive buffer.
2	202	02CA	init_memory: Main initialization routine.
3	40	0328	init_variables: Initialize BASIC system variables in a similar way to the BASIC ROM 'NEW' routine and initialize own variables in printer buffer.
4	58	043A	NMI_VECTOR: Jump to NMI service routine (Copied to NMI_JUMP).
4	61	043D	init_48k: Initialise pointers for 48k systems.
4	81	0451	48k_pointer_table.
4	109	046D	init_16k: Initialise pointers for 16k systems
4	129	0481	16k_pointer_table.
4	157	049D	initial_CHINFO: BASIC channel information initialization data.
4	178	04B2	initial_STRMS: BASIC stream addresses initialization data.
4	192	04C0	menu_data: Main menu page data (with teletext control codes).
6	64	0640	display_menu: Display the main menu and wait for enter key to be pressed.
6	166	06A6	print_character: Print character to the screen
7	59	073B	print_half_row: Print 4 pixel rows of character bitmap over 8 pixel rows of screen (double height).
7	76	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.
7	102	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.
7	128	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.
7	154	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.
7	180	07B4	print_normal: Print 8 pixel rows of font data (a normal height character).
7	197	07C5	print_column_0: Write character data at column that is a multiple of 4.
7	211	07D3	print_column_1: Write character data at column that is 1 greater than a multiple of 4.
7	242	07F2	print_column_2: Write character data at column that is 2 greater than a multiple of 4.
8	15	080F	print_column_3: Write character data at column that is 3 greater than a multiple of 4.
8	27	081B	screen_address: Calculate the address in screen RAM of the second byte of character row in A.
8	77	084D	set_attrs: Set screen attributes corresponding to screen address in character screen address variable to value in temp_attr.
8	176	08B0	clear_screen: Clear display bitmap and attributes.
8	196	08C4	clear_page_buffer: Clear page display buffer to spaces.
8	223	08DF	clear_receive_rows: Clear all rows except header in page receive buffer.
8	247	08F7	decode_row: Decode row of teletext data and render it to the screen.
9	152	0998	alpha_colour_code: Alphanumeric colour control code.
9	170	09AA	normal_code: Handle normal size control code.
9	182	09B6	double_code: Handle double height control code.
9	201	09C9	mosaics_colour_code: Handle a mosaics colour code.
9	235	09EB	conceal_code: Handle conceal code.
9	251	09FB	contiguous_code: Handle contiguous mosaics cotrol code.
10	2	0A02	separated_code: Handle separated mosaics cotrol code.
10	23	0A17	black_background_code: Clear paper colour bits of temp_attr.
10	34	0A22	new_background_code: Copy ink colour bits of temp_attr to paper colour bits.
10	55	0A37	hold_mosaics_code: Handle hold mosaics code.
10	76	0A4C	Release_mosaics_code: Handle release mosaics code.
10	82	0A52	code_set_at: Display character.
10	184	0AB8	translate_colour: Translate an alphanumeric colour code to spectrum attribute colour.
10	212	0AD4	colour_translation_table.
10	220	0ADC	set_character_pointer: Set character_pointer to start of current row in page display buffer.
10	250	0AFA	wait_and_decode_page: Wait for page_ready_flag, and check for key presses.
11	70	0B46	decode_page: Decode and render 24 rows.
11	96	0B60	font_data: Alphanumeric character set font data.
14	96	0E60	init_mosaics: Initialize font data for contiguous and separated mosaic character sets.
14	201	0EC9	generate_mosaics: Generate font data for contiguous mosaic with the character code in B at the address in HL.
14	253	0EFD	copy_blast_through: Copy blast through alphanumerics font data.
15	6	0F06	Copy 32 contiguous mosaic characters from address in HL to address in DE, separating the columns.
15	17	0F11	write_top_sixels: Write bitmap in D to three rows of font data.
15	24	0F18	set_right_bits: Set right half of mosaic bits.
15	31	0F1F	get_keypress.
15	52	0F34	scan_keyboard: Loop through keyboard rows to detect a keypress and return return key code.
15	122	0F7A	keyboard_lookup_table: Mapping between spectrum keyboard port read and keycode.
15	162	0FA2	detect_any_key: Detect if any key is pressed.
15	178	0FB2	handle_keypress: Handle a keypress while in teletext mode.
15	251	0FFB	toggle_bright: Toggle bright flag.
16	9	1009	exit_routine: Relocatable exit to BASIC routine.
16	52	1034	no_printer: Break out of printer loop gracefully.
16	56	1038	print: Printer routine for Sinclair ZX Printer or Alphacom 32.
16	156	109C	enter_page: Get valid page number and display digits in row 0.
16	235	10EB	enter_page_and_clear: Get valid page number then clear the page buffer.
16	240	10F0	enter_subcode_and_clear: Get valid page subcode then clear the page buffer.
17	85	1155	get_dec_digit: Wait for a keypress in the range 0-9.
17	99	1163	select_channel: Channel selection and tuning display.
17	196	11C4	hold_indicator: Page hold string.
17	200	11C8	hold_page: Pressed H to hold page.
18	32	1220	toggle_reveal.
18	43	122B	data_to_header_row: Copy header row data from recieve buffer to page display buffer.
18	67	1243	display_header_row: Decode and display the header row.
18	87	1257	copy_page_data: Copy received page data into page display buffer.
18	119	1277	clear_page_number: Copy page number display to number_display_buffer and clear to spaces.
18	147	1293	restore_number: Copy number_display_buffer into page number display.
18	166	12A6	pagename_string: String which gets copied to RAM_pagename_string.
18	177	12B1	save_routine: Relocatable save page routine.
19	146	1392	Unused
19	148	1394	save_instruction: BASIC save instruction string.
19	180	13B4	init_hamming_table: Create 256 byte look up table of Hamming 8/4 decoded bytes.
20	129	1481	store_hamming_nibble: Read the four data bits from hamming coded byte into address in HL
20	162	14A2	hamming_error_bits_table: Values to XOR with byte to correct hamming errors.
20	170	14AA	store_hamming_error
20	174	14AE	correct_and_store_nibble: Correct a single bit error at bit position in C.
20	187	14BB	warm_start_routine: Relocatable "warm start" from BASIC routine.
20	213	14D5	clear_header: Clear page header to spaces.
20	240	14F0	copy string in HL to page header
21	18	1512	pause_3s: Pause for 3 seconds
21	28	151C	get_hex_digit: Wait for a keypress in the range 0-9 or A-F.
21	50	1532	downloader_not_present: Display downloader not present message for 3 seconds.
21	58	153A	downloader_not_present_message
21	81	1551	OELRoutine02
22	169	16A9	command_pointers_1
22	219	16DB	command_pointers_2
22	229	16E5	OELBytes01
22	251	16FB	Unused
23	10	170A	OELRoutine03
23	61	173D	copy_pointer_to_escape_table
23	80	1750	OELRoutine05
23	86	1756	OELRoutine06
23	100	1764	OELRoutine07
23	152	1798	OELRoutine08
23	175	17AF	OELRoutine09
23	186	17BA	OELRoutine10
23	191	17BF	OELRoutine11
23	197	17C5	telesoftware messages
24	90	185A	OELRoutine12
25	95	195F	OELRoutine13
25	117	1975	OELRoutine14
26	43	1A2B	OELRoutine15
26	94	1A5E	OELRoutine16
26	142	1A8E	Data block at 1A8E
26	157	1A9D	OELRoutine17
26	187	1ABB	parity_error
26	193	1AC1	OELRoutine18
26	248	1AF8	OELRoutine19
27	33	1B21	hex_to_int: Convert hex digit in A to integer in B or $FF if invalid.
27	58	1B3A	OELRoutine20
27	63	1B3F	OELRoutine21
27	77	1B4D	OELRoutine22
27	80	1B50	OELRoutine23
27	126	1B7E	illegal_type: Display illegal_type_message and jump into page decode loop.
27	132	1B84	missing_operand: Display parity_error_message and jump into page decode loop.
27	138	1B8A	datatype_and_hardware: Parse Datatype and Hardware command.
28	31	1C1F	OELRoutine24
29	178	1DB2	Routine at 1DB2
29	183	1DB7	Routine at 1DB7
29	188	1DBC	Routine at 1DBC
29	193	1DC1	Routine at 1DC1
29	196	1DC4	Routine at 1DC4
30	27	1E1B	Routine at 1E1B
30	55	1E37	Routine at 1E37
30	63	1E3F	Routine at 1E3F
30	66	1E42	Routine at 1E42
30	115	1E73	telesoftware error messages
31	25	1F19	Routine at 1F19
31	31	1F1F	Routine at 1F1F
31	40	1F28	Routine at 1F28
31	64	1F40	Routine at 1F40
31	80	1F50	display_error: Display error message and jump into page decode loop.
31	103	1F67	Routine at 1F67
31	127	1F7F	Routine at 1F7F
31	141	1F8D	get_hex: Get a hexadecimal keypress.
31	152	1F98	Unused
32	0	2000	decoder_RAM: Packet buffer in decoder RAM
91	0	5B00	temp_attr
91	1	5B01	save_return_pointer
91	3	5B03	char_addr
91	7	5B07	mosaics_flag
91	8	5B08	separated_mosaics_flag
91	9	5B09	double_height_flag
91	10	5B0A	row_has_double_flag
91	11	5B0B	column_offset
91	12	5B0C	character_code
91	13	5B0D	character_pointer
91	15	5B0F	hold_mosaic_character
91	16	5B10	skip_next_row_flag
91	17	5B11	row_number
91	18	5B12	hold_mosaics_flag
91	19	5B13	ignore_packets_flag
91	20	5B14	page_found_flag
91	21	5B15	packet_data_pointer
91	23	5B17	magazine_number
91	24	5B18	page_tens
91	25	5B19	page_units
91	26	5B1A	control_register
91	27	5B1B	bright_attr
91	28	5B1C	current_attr_address
91	30	5B1E	page_ready_flag
91	31	5B1F	held_separated_flag
91	32	5B20	conceal_flag
91	33	5B21	reveal_flag
91	34	5B22	number_display_buffer
91	42	5B2A	parity_flags
91	46	5B2E	hamming_table_counter
91	47	5B2F	input_buffer
91	58	5B3A	inhibit_display
91	59	5B3B	disable_rolling_headers
91	60	5B3C	interrupt_reset_flag
91	61	5B3D	backup_exit_pointer
91	63	5B3F	RAM_pagename_string
91	80	5B50	NMI_JUMP
91	83	5B53	colour_attr
91	85	5B55	field_header_flag
91	86	5B56	subpage_search_flag
91	87	5B57	subcode_digits
91	97	5B61	counter_reset_address
91	99	5B63	OELWord01
91	101	5B65	lone_table_pointers
91	103	5B67	escape_table_pointers
91	105	5B69	lone_table_values
91	107	5B6B	escape_table_values
91	109	5B6D	page_display_buffer_pointer
91	111	5B6F	page_receive_buffer_pointer
91	113	5B71	mosaics_font_pointer
91	115	5B73	hamming_decode_table_pointer
91	117	5B75	contiguous_blast_through
91	119	5B77	separated_blast_through
91	121	5B79	warm_start_pointer
91	123	5B7B	exit_pointer
91	125	5B7D	save_page_pointer
91	127	5B7F	OELWord06
91	129	5B81	OELWord07
91	131	5B83	OELWord08
91	133	5B85	OELWord09
91	135	5B87	OELWord10
91	137	5B89	OELWord11
91	139	5B8B	OELVariable01
91	140	5B8C	OELVariable02
91	141	5B8D	OELWord12
91	143	5B8F	OELWord13
91	147	5B93	OELVariable03
91	148	5B94	OELVariable04
91	149	5B95	OELVariable05
91	150	5B96	OELVariable06
91	151	5B97	OELVariable07
91	152	5B98	OELVariable08
91	153	5B99	OELBuffer01
91	185	5BB9	OELVariable09
91	186	5BBA	OELFlag01
91	187	5BBB	OELVariable10
91	188	5BBC	OELVariable11
91	189	5BBD	OELWord14
91	191	5BBF	OELWord15
91	203	5BCB	OELVariable12
91	204	5BCC	warm_start_vector
91	207	5BCF	OELVariable13
91	208	5BD0	OELVariable14
91	209	5BD1	OELVariable15
91	212	5BD4	OELFlag02
91	213	5BD5	telesoftware_pointer
91	215	5BD7	print_pointer
91	217	5BD9	OELWord17
91	219	5BDB	OELWord18
91	221	5BDD	OELWord19
91	223	5BDF	OELWord20
91	225	5BE1	OELWord21
91	227	5BE3	OELWord22
91	229	5BE5	OELWord23
91	238	5BEE	OELWord24