Memory map

Page	Byte	Address	Description
64	0	16384	Data block at 16384
92	72	23624	Port 254 shadow
92	94	23646	Message at 23646
92	97	23649	Data block at 23649
92	235	23787	Message at 23787
92	240	23792	Data block at 23792
93	3	23811	Message at 23811
93	8	23816	Data block at 23816
93	26	23834	Message at 23834
93	32	23840	Data block at 23840
93	39	23847	Message at 23847
93	49	23857	Data block at 23857
95	157	24477	Message at 24477
95	161	24481	Data block at 24481
96	8	24584	Message at 24584
96	12	24588	Data block at 24588
96	29	24605	Game runtime data
96	39	24615	Number of aliens remaining
96	78	24654	Game initialisation data
96	88	24664	Screen initialisation data
96	127	24703	Start of game, from LOADer and new game loop
96	218	24794	Storage byte for routine that follows
96	219	24795	Move aliens along, based on speed control value
96	247	24823	Reset game data
97	3	24835	Initialise new screen data
97	36	24868	Dynamic pause
97	76	24908	delay_ms (approx)
97	87	24919	Advance alien start row
97	102	24934	Temp store for the print score code
97	103	24935	Print score
97	157	24989	Reset score, update high score
97	201	25033	Temporary store for the counter of lives remaining to draw
97	202	25034	Draw lives remaining on top row
98	17	25105	Award extra life
98	72	25160	Game over
98	140	25228	Initialise game screen attributes
98	194	25282	Data block at 25282
99	98	25442	Spaceship handler
99	248	25592	Hit spaceship
100	28	25628	Spaceship noise
100	39	25639	Bonus table
100	43	25643	Spaceship has been hit, award bonus
100	86	25686	Add A to HL (1)
100	91	25691	Runtime data for alien bullet firing loop
100	108	25708	Move alien bullets.
100	137	25737	Advance IX to point to next alien bullet slot
100	149	25749	Generate alien bullets
100	253	25853	Move alien bullet
101	120	25976	Clear alien bullets
101	138	25994	Increment alien bullet position
101	145	26001	Clear bottom character row
101	164	26020	Remove alien bullet
101	182	26038	Has an alien been hit?
101	193	26049	Bullet and alien collision check, Y axis
101	241	26097	Data block at 26097
102	42	26154	Bullet and alien collision check, X axis
102	113	26225	Alien hit
102	208	26320	Alien hit, zero out the UDGs
102	225	26337	Draw alien explosion
103	7	26375	Recalc alien numeric data on alien hit
103	91	26459	Scores table based on alien rows.
103	96	26464	Increase score when alien hit
103	116	26484	Add A to HL (2)
103	121	26489	Move bullet temp
103	122	26490	Player bullet interception detection
103	198	26566	Handle player inputs.
103	219	26587	Keypress detection
104	51	26675	Redraw player ship
104	88	26712	Select player ship clear sprite data
104	97	26721	Keypress routine's fire-released flag
104	98	26722	Player ship sprite data
105	3	26883	Fire pressed
105	36	26916	Draw the player bullet.
105	67	26947	Clear player bullet
105	84	26964	Temporary store for where the new ship should end up at the end of the scroll animation.
105	85	26965	New player ship
105	125	27005	Copy alien UDG data to a screen row
105	149	27029	Temporary value used for initialising aliens
105	150	27030	Initialise alien position data
105	217	27097	Find the data structure which represents the row of aliens
105	234	27114	Find alien UDG data
105	247	27127	Aliens data
106	199	27335	Original assembler strings
106	213	27349	Unused
106	214	27350	Message at 27350
106	225	27361	Data block at 27361
106	253	27389	Message at 27389
107	16	27408	Unused
107	17	27409	Message at 27409
107	30	27422	Data block at 27422
107	52	27444	Message at 27444
107	55	27447	Data block at 27447
107	84	27476	Message at 27476
107	95	27487	Unused
107	96	27488	Message at 27488
107	104	27496	Data block at 27496
107	107	27499	Message at 27499
107	114	27506	Data block at 27506
107	153	27545	Message at 27545
107	156	27548	Data block at 27548
108	50	27698	Message at 27698
108	53	27701	Data block at 27701
109	159	28063	Message at 28063
109	162	28066	Data block at 28066
109	176	28080	Message at 28080
109	179	28083	Data block at 28083
110	225	28385	Message at 28385
110	228	28388	Data block at 28388
110	244	28404	Message at 28404
110	247	28407	Data block at 28407
111	145	28561
111	181	28597	Data block at 28597
111	185	28601	Message at 28601
111	189	28605	Data block at 28605
113	22	28950	Message at 28950
113	25	28953	Data block at 28953
113	67	28995	Message at 28995
113	70	28998	Data block at 28998
115	83	29523	Message at 29523
115	86	29526	Data block at 29526
115	91	29531	Message at 29531
115	95	29535	Data block at 29535
116	219	29915	Message at 29915
116	223	29919	Data block at 29919
119	61	30525	Message at 30525
119	64	30528	Data block at 30528
119	73	30537	Message at 30537
119	77	30541	Data block at 30541
119	191	30655	Message at 30655
119	194	30658	Data block at 30658
119	195	30659	Message at 30659
119	198	30662	Data block at 30662
120	37	30757	Message at 30757
120	40	30760	Data block at 30760
120	137	30857	Move aliens
121	19	30995	Move one row of aliens down
121	99	31075	Initialise draw aliens
121	131	31107	Alien data structure
121	143	31119	Prepare alien row drawing data
121	222	31198	Print one row of aliens
122	25	31257	Draw an alien sprite scan line
122	58	31290	Set INK colour of attributes
122	71	31303	Set alien colour band
122	95	31327	Remove barriers when the aliens get low
122	139	31371	UDGs which make up the barriers.
122	187	31419	Barrier top row string
122	192	31424	Barrier middle row string
122	197	31429	Barrier bottom row string
122	202	31434	Temporary value for barrier loop
122	203	31435	Temporary value for barrier rows
122	204	31436	Draw barriers
123	21	31509	Data block at 31509
123	39	31527	Has bullet hit a barrier?
123	146	31634	Set pixel
123	152	31640	Clear pixel
123	159	31647	XOR pixel
123	165	31653	Clear screen byte but leave pixel
123	170	31658	Screen address calculation table, used by pxy2saddr
124	178	31922	pxy2saddr
124	216	31960	Draw or undraw sprite
124	240	31984	Data block at 31984
124	242	31986	Data block at 31986
124	243	31987	Sound burbler
125	34	32034	Click speaker bit, causes 2 clicks separated by the given pitch
125	55	32055	Randomish numbers
125	59	32059	Update cycler values
125	112	32112	Printable score
125	127	32127	Generate printable score
125	159	32159	Find digit char UDG
125	174	32174	Character set for scores
125	254	32254	cxy2saddr
126	19	32275	Print UDG at HL to screen at BC
126	31	32287	Clear screen pixel data
126	46	32302	Print string at return address
126	51	32307	Print positioned string at HL
126	55	32311	Print string at HL
126	87	32343	Attribute address finder, cx,cy to attr address
126	104	32360	A 2 byte entry from the table at 32362 is copied into here by the ship drawing routine. It's used as a destination for the jump at 32362
126	106	32362	Update pixel
126	110	32366	This is a jump table with 4 entries.
126	118	32374	Prime pixel update
126	142	32398	Find character
126	156	32412	Data block at 32412
255	89	65369	Message at 65369
255	92	65372	Data block at 65372
255	113	65393	Message at 65393
255	119	65399	Data block at 65399
255	140	65420	Message at 65420
255	143	65423	Data block at 65423
255	148	65428	Message at 65428
255	151	65431	Data block at 65431
255	164	65444	Message at 65444
255	167	65447	Unused
255	169	65449	Message at 65449
255	175	65455	Data block at 65455
255	185	65465	Message at 65465
255	191	65471	Unused
255	193	65473	Message at 65473
255	199	65479	Unused
255	201	65481	Message at 65481
255	207	65487	Data block at 65487
255	217	65497	Message at 65497
255	223	65503	Data block at 65503
255	249	65529	Message at 65529
255	255	65535	Unused