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sta (157), lda (154), the (147), and (68), for (57), row (46), journal (44), ramuse (41), code (40), digit (39), player (35), 156 (32), txt (30), bit (27), lsr (27), this (26), jsr (26), cas (26), from (25), graphics (25), inc (24), hardware (22), loop (21), bne (21), beq (21), number (19), playfield (19), bmi (19), right (18), ldx (18), cmp (18), bpl (18), rts (18), wsync (18), missile (17), clear (17), are (16), rows (16), left (16), pf1 (16), jmp (16), 155 (16), next (15), clc (15), adc (15), asl (15), off (14), pointer (14), turn (13), get (13), bcc (13), main (13), all (12), 157 (12), eor (12), 259 (12), ma3 (12), pf2 (11), dex (11), tay (11), m97 (11), tanks (10), top (10), ldy (10), draw (10), m95 (10), tank (9), pattern (9), back (9), lsb (9), score (9), set (9), screen (9), sec (9), m99 (9), scanlinenumber (9), table (8), each (8), pf0 (8), frame (8), done (8), ram_scanlinenumber (8), with (8), scratch1 (8), m88 (8), pdf (8), players (7), over (7), start (7), pictures (7), through (7), wait (7), current (7), duplicate (7), last (7), hard_pf1 (7), sbc (7), tax (7), called (7), game (6), line (6), digits (6), values (6), half (6), bcs (6), bvc (6), lots (6), audv0 (6), swchb (6), collisions (6), colorp0 (6), md1 (6), m85 (6), m8a (6), m9f (6), nextright (6), nextleft (6), soundramuse (6), soundhardware (6), defender (6), not (5), field (5), bytes (5), bottom (5), pointers (5), entries (5), f5c5 (5), area (5), f0cd (5), ram_nextleft (5), ram_nextright (5), flag (5), hold (5), time (5), switches (5), f1d0 (5), f1f1 (5), audc0 (5), audf0 (5), dec (5), skipplayfield (5), f4d4 (5), scorep1 (5), player0row (5), framecounter (5), combat (5), asm (5), soundcode (5), more (4), close (4), simple (4), complex (4), clouds (4), air (4), just (4), f779 (4), blank (4), vertical (4), out (4), use (4), jet (4), plane (4), picture (4), add (4), drawing (4), numbers (4), data (4), hmove (4), visible (4), two (4), f083 (4), hard_wsync (4), calculated (4), index (4), only (4), 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pf0graphics (3), m84 (3), f508 (3), m8b (3), f48b (3), f476 (3), f3f2 (3), f3f0 (3), f3de (3), f38c (3), f30b (3), playerxpicture (3), mb0 (3), mac (3), mb1 (3), leftdigitmsd (3), leftdigitlsd (3), player1row (3), f192 (3), mdc (3), f182 (3), sync (3), ntsc (3), bank7 (3), bank3 (3), bank2 (3), bank1 (3), invaders (3), sound (3), jpg (3), reset (2), f000 (2), maybe (2), f7fe (2), vectors (2), f1ae (2), f7d8 (2), playfields (2), f324 (2), planes (2), f32b (2), guides (2), pre (2), levels (2), f423 (2), f42a (2), f43e (2), copies (2), empty (2), tables (2), f785 (2), f791 (2), f79e (2), you (2), makes (2), cloud (2), different (2), f7ae (2), f7ba (2), f7d4 (2), f7d0 (2), f7cc (2), playerpicmsb (2), playerpiclsb (2), f765 (2), plyrnumsize (2), f739 (2), f736 (2), f733 (2), f70f (2), f25e (2), f627 (2), f5f7 (2), here (2), electron (2), beam (2), lines (2), f0ca (2), first (2), ram_leftdigitmsd (2), ram_leftdigitlsd (2), combine (2), ram_rightdigitmsd (2), ram_rightdigitlsd (2), select (2), newly (2), bogus (2), before (2), lsd (2), msd (2), make (2), same (2), where (2), timing (2), speed (2), borrow (2), lookup (2), within (2), window (2), ram_playerxpicture (2), position (2), maps (2), enable (2), when (2), php (2), runs (2), entry (2), backwards (2), reflection (2), positive (2), negative (2), starts (2), bump (2), hard_grp1 (2), hard_pf0 (2), hard_pf2 (2), pressed (2), f16b (2), sty (2), sed (2), resp1 (2), byte (2), store (2), bvs (2), cpx (2), vdelp0 (2), refp0 (2), resmp1 (2), inpt4 (2), f504 (2), other (2), f007 (2), variables (2), ram (2), f5bf (2), colup0 (2), f5a7 (2), f57a (2), f572 (2), f556 (2), f548 (2), f546 (2), f544 (2), mbb (2), f525 (2), maa (2), f27c (2), f50f (2), f507 (2), f446 (2), f4f9 (2), f4f7 (2), me4 (2), f4ed (2), f4e7 (2), f4de (2), f4d6 (2), f4d0 (2), f4c8 (2), f4c6 (2), mb2 (2), f4b7 (2), f4b4 (2), f496 (2), f47d (2), f454 (2), f444 (2), f439 (2), f432 (2), f421 (2), missile0row (2), f3f6 (2), f3b4 (2), f300 (2), f3d9 (2), f3c5 (2), f3bf (2), f3b7 (2), f3a2 (2), f380 (2), f358 (2), f37b (2), f316 (2), f36b (2), f349 (2), m93 (2), m91 (2), f33c (2), f338 (2), f31c (2), f30c (2), f2f9 (2), f2da (2), f2cc (2), f2d4 (2), f2cb (2), f2bb (2), f2a9 (2), f2a8 (2), md4 (2), f298 (2), f290 (2), f22a (2), f250 (2), f23d (2), f21e (2), f21c (2), f214 (2), f1f4 (2), scoregraphics (2), m81 (2), f1bb (2), m80 (2), f1a3 (2), f19d (2), f170 (2), maskrightnumber (2), f157 (2), grp1 (2), f0df (2), f13b (2), f127 (2), f114 (2), f0f2 (2), ctrlpf (2), rightdigitmsd (2), rightdigitlsd (2), f070 (2), vblank (2), f05c (2), drawvisible (2), counter (2), trigger (2), timer (2), signal (2), 2752 (2), vsync (2), starttvframe (2), info (2), blend (2), bedlam (2), code1 (2), ramuse1 (2), pyramid (2), bank6 (2), bank5 (2), bank4 (2), bank0 (2), after_25 (2), after_24 (2), after_23 (2), after_22 (2), after_21 (2), after_20 (2), after_19 (2), after_18 (2), after_17 (2), after_16 (2), after_15 (2), after_14 (2), after_13 (2), after_12 (2), after_11 (2), after_10 (2), after_9 (2), after_8 (2), after_7 (2), after_6 (2), after_5 (2), after_4 (2), after_3 (2), after_2 (2), after_1 (2), after_start (2), early (2), asteroids (2), atari2600 (2), scramble (2), may2025 (2), func (2), main2 (2), vectorrom (2), gfx2 (2), sprites (2), gfx1 (2), theory (2), boot (2), 1loader (2), f7fa, nmi, f7fc, irq, 110f, debug, f7da, f7db, f7de, f7df, f7e0, f7e1, f7e3, f7e5, f7e8, f7e9, f7eb, f7ec, f7ed, f7ee, f7f0, f7f2, f7f4, f6cf, f6d7, f6df, f6e7, f6ef, f6f7, f6ff, f707, guidance, f713, f715, f716, than, others, f718, f71a, f71b, f71c, f71d, f71f, f721, f722, f723, f725, f727, f729, f72b, f72c, f72e, f730, f731, f732, f737, f738, f73c, f73d, f73e, f73f, f740, f741, f742, f743, f744, f745, f746, f747, f74a, f74c, f74d, f74e, f74f, f750, f751, f752, f753, f754, f755, f756, f757, f759, f75a, f75b, f75c, f75d, f75f, f761, f763, quad, colors, f767, f768, f769, f76a, f76d, f76e, f76f, f770, f771, f772, f773, f774, f775, patterns, has, three, 192, mirrored, f7a2, fatter, could, also, smaller, bet, larger, was, intended, second, they, ran, f7ad, f7c6, f7c9, four, fields, treats, f68f, f697, f69f, f6a7, f6af, f6b7, f6bf, f6c7, f64f, f657, f65f, f667, f66f, f677, f67f, f687, f5ca, f5cf, f5d4, f5d9, f5de, f5e3, f5e8, f5ed, f5f2, f5f8, f5f9, f5fb, f5fd, f5ff, f600, f603, f604, f605, f606, f609, f60b, f60d, f60f, f617, f61f, f62f, f63f, f647, down, todo, blurb, key, f054, counting, f056, easier, f058, ensure, horiz, f05a, apply, movement, objects, f05f, reach, f061, 37th, f063, collision, flags, f065, f067, tsx, save, f068, f06a, f06c, f06e, f072, f073, f075, f077, f079, f07b, per, f07d, f07f, f081, z26, log, pass, blanks, aborted, f085, f087, f089, f08b, f08e, f090, f092, f094, f097, f099, f09b, f09d, f09f, f0a1, f0a3, f0a6, f0a8, f0aa, f0ac, f0af, ram_maskrightnumber, f0b1, f0b3, f0b5, f0b7, f0b9, f0bb, f0bc, write, quickly, gets, f0be, f0c0, f0c2, f0c4, f0c6, f0c8, f0cf, f0d1, f0d3, f0d5, hard_ctrlpf, reflect, f0d7, ram_colorp0, f0d9, hard_colup0, f0db, ram_colorp1, f0dd, hard_colup1, rest, middle, let, pick, video, midway, across, using, writes, pointing, playing, missiles, f0e1, f0e2, f0e3, ram_player0row, f0e5, interleaved, f0e7, f0e9, f0ea, f0ec, f0ee, f0f0, f0f6, f0f8, ram_missile1row, f0fa, f0fc, status, register, thus, push, f0fe, f0ff, ram_missile0row, f101, f103, f105, forwards, reflects, happens, count, twelve, difficult, easy, assumes, fourth, uses, backed, that, looks, like, check, keeps, f106, f108, non, reflected, region, 152, f10a, run, f10e, tall, f110, divide, f111, f112, covers, f113, ram_player1row, f116, how, 6502, works, f117, f119, f11b, nop, f11c, f11e, f11f, f121, f123, f125, ram_skipplayfield, goes, f12b, f12d, f12f, ram_pf0graphics, f131, f133, ram_pf1graphics, f135, f137, ram_pf2graphics, f139, doing, f13d, have, f13f, 236, f141, 258, see, twice, f143, ram_stackpointer, restore, f145, eored, 11101100, checked, way, which, stores, below, f146, hard_enam0, f148, hard_enam1, f14a, f14c, f14e, f150, f152, f154, f156, f15a, switch, f15b, f15d, longer, f15f, f161, f163, f165, f167, f169, f16e, f172, f174, f176, f178, f17a, f17c, f17e, f180, f184, f186, f188, f18a, f18c, f18e, f190, f195, f197, f199, f19b, f19f, f1a1, initialization, f1a8, f1aa, f1ac, f1b1, f1b3, f1b5, f1b7, f1b9, f1bd, f1be, f1bf, f1c1, f1c3, f1c5, f1c6, f1c8, f1ca, f1cc, f1ce, f1d3, f1d5, f1d7, f1d9, f1db, f1dd, f1df, f1e1, f1e3, f1e5, f1e7, f1e9, f1eb, f1ed, f1ef, f1f2, f1f6, f1f8, f1fa, f1fb, f1fc, f1fd, f1ff, f201, f203, f205, f206, f207, f209, f20a, f20b, f20c, now, f20e, f210, f211, f213, f216, f218, f21a, f220, f222, f225, f226, f229, f22c, f22e, f22f, f230, f232, f233, f235, f236, f239, f23a, f23c, rol, f23e, f241, f243, f245, f247, f248, f249, f24a, f24b, f24d, f251, f253, f256, f258, f25a, f25b, f25d, f261, f263, f265, f267, f269, f26a, f26c, f26e, f270, f272, f274, f276, f278, hmm1, hmm0, f27e, f280, f281, f283, f285, f286, f288, f28a, f28c, f28e, f292, f294, f296, f29a, f29c, f29e, f2a2, f2a4, f2a6, vdelp1, f2ab, f2ad, f2ae, f2b0, refp1, f2b2, f2b4, f2b5, f2b7, f2b9, f2bc, f2be, f2bf, tya, f2c0, f2c1, f2c2, f2c3, f2c5, f2c6, f2c8, f2c9, f2ce, f2d0, f2d2, f2d3, f2d5, f2d6, f2d7, f2d9, f2dc, f2dd, f2df, f2e1, f2e3, f2e5, f2e7, f2e9, f2ea, f2ec, f2ee, f2f0, f2f2, f2f4, f2f6, f2fb, f2fd, f2fe, f2ff, f302, f304, f306, f309, f30e, f311, f313, f318, f31a, f31e, f320, f322, f327, f328, f32a, f32e, f330, f332, f334, f336, f33a, f33e, f340, f342, f344, f345, f347, f34b, f34d, f350, f351, f352, f353, f354, f356, f35a, f35b, f35c, f35f, f361, f362, f365, f367, f369, f36e, f371, f372, f373, f374, f375, f377, f378, f37a, f37c, f37e, f382, f384, f386, f388, f38a, f38e, f390, f392, f394, f396, f398, f39a, f39c, f39e, f3a0, f3a4, f3a6, f3a8, f3aa, f3ac, f3b0, f3b2, f3b6, f3b9, f3bb, inpt5, f3bd, f3c2, f3c8, f3cd, f3cf, f3d2, f3d4, f3d6, f3db, f3e0, f3e2, f3e4, f3e6, f3e8, f3ea, f3ec, f3ee, f3f4, f3f8, f3fa, f3fb, f3fd, f3ff, f401, f403, f405, f407, f409, f40b, f40d, f412, f414, f416, f418, f41a, f41c, f41e, f420, f426, f428, audv1, f42d, audc1, f42f, f430, f433, f435, f437, f43b, f43c, f43d, f441, audf1, f443, f448, did, f44a, f44c, f44e, f450, f452, f456, f458, f459, f45b, f45c, give, point, f45e, f460, normal, f461, f462, f463, f465, f467, f469, f46b, f46d, f46f, f471, f473, f475, f478, f47a, f47f, f481, f483, f485, f487, f489, f48d, f48f, f491, f493, f498, f49a, f49c, f49e, f4a0, f4a2, f4a4, f4a6, f4a8, f4aa, f4ac, f4ae, f4b0, f4b2, f4b9, f4bb, f4bd, f4bf, f4c1, f4c3, f4c9, f4cb, f4cd, f4d2, f4d8, f4da, f4dc, f4e0, f4e2, f4e4, f4e9, f4eb, f4ef, f4f1, f4f3, f4f5, f4fb, f4fc, f4fe, f502, f509, f50b, f50c, f511, f512, f515, f518, f51a, f51c, f51e, f520, f522, f524, type, f527, f52a, f52c, f52f, f531, f533, f534, f535, f537, f538, f53a, f53c, f53e, f540, f542, f54a, f54b, f54c, f54e, f550, f552, f554, f558, f7xx, f55a, f55c, f55e, f560, f563, f565, f567, f56a, f56c, f56f, f571, f574, f576, f578, f57b, f57c, f57f, f581, f584, f586, f588, f58a, f58b, f58c, f58d, f58e, f58f, f591, f594, f596, f598, f59a, f59c, f59f, f5a1, f5a3, f5a5, f5a9, f5ae, f5b0, f5b2, f5b4, f5b6, f5b8, f5b9, f5ba, f5bc, incrementing, until, inx, location, f5c0, f5c2, f5c4, nusiz1, f75e, nusiz0, resp0, mbc, cxppmm, cxp0fb, cxm0fb, m9a, cxm0p, mdb, m96, enam0, missile1row, colup1, colorp1, cxclr, intim, increment, period, f032, f034, motion, f036, f038, f03a, f03c, f03e, electrons, f040, drain, f042, f044, f046, scan, f048, f04a, third, f04c, release, f04e, machine, f050, cycles, 228, scanlines, f053, tim64t, hmclr, f014, f017, f01a, pro, f01d, f020, f023, f026, f029, scores, f02c, f02f, sei, interrupts, f001, binary, f002, 1_ff, f004, ghosts, 0_ff, f005, f00a, f00c, inputs, f00f, debounce, f011, swbcnt, version, usage, zip, tools, stoned, morris, worm, virus, usvdobjs, ssvdobjs, section9, section8, section7, section6, section5, section4, section3, section2, section1, xenos, raakatu, code2, ramuse2, hauntedhouse, hardwaredisk, hardwarelevel1, hardwarelevel2, trs80, tetris, bank1f, bank1e, bank1d, bank1c, bank1b, bank1a, bank19, bank18, bank17, bank16, bank15, bank14, bank13, bank12, bank11, bank10, bank0f, bank0e, bank0d, bank0c, bank0b, bank0a, bank09, bank08, bank07, bank06, bank05, bank04, bank03, bank02, bank01, bank00, link, awakening, gameboy, kid, icarus, zelda, nes, doubleback, audio, analyzer, downland, level, daggorath, popcorn, mega, bug, savegameviewer, walk, madness, minotaur, raaka, coco, data350, code350, dataorg, codeorg, colossalcave, command, codebank7, codebank6, codebank5, codebank4, codebank3, codebank2, codebank1, codebank0, burger, entombed, doublegap, double, gap, codepal, chess, battle, zone, stella, sea, wolf, pilot, pit, tempest, scap, hhi, foreground, background, phoenix, pooyan, dvgprom, soundboard, mainboard, omega, race, moonpatrolsound, textcolors, spritecolorsets, spritecolors, imagebackgroundcolors, gfx5, city, gfx4, hills, gfx3, mountains, text, moon, patrol, cpu1fix, prompalettesprite, prompalettechar, promcolors, characters, cpu3, cpu2, secondary, cpu1, galaga, gfx, frogger, donkey, kong, soundrom, vid, rom, cpu, mapping, bankfixed, memorymap, graphicsandcharacterassetinfo, crazyclimbermemorymapinfo, charenc, cclimber, buildings, bigspritegraphics, crazy, climber, centipede, dvg, arcade, orig, rainbow, islands, amiga, page, site, home, contact,

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ank03 bank04 bank05 bank06 bank07 bank08 bank09 bank0a bank0b bank0c bank0d bank0e bank0f bank10 bank11 bank12 bank13 bank14 bank15 bank16 bank17 bank18 bank19 bank1a bank1b bank1c bank1d bank1e bank1f journal tetris 1 ramuse code journal trs80 hardwarelevel2 hardwarelevel1 hardwaredisk hauntedhouse ramuse1 code1 ramuse2 code2 journal pyramid ramuse code ramuse1 code1 journal raakatu ramuse code journal bedlam ramuse code journal xenos ramuse code section1 section2 section3 section4 section5 section6 section7 section8 section9 ssvdobjs usvdobjs journal virus morris worm 1 journal stoned journal tools blend blend zip journal combat ntsc main game loop start the tv frame draw the visible screen data area numbers tank pictures jet pictures plane pictures playfields vectors combat ntsc hardware info ram usage this is the ntsc version of the code f000 78 sei turn off interrupts f001 d8 cld binary mode not bcd f002 a2 ff ldx ff stack pointer to 1_ff f004 9a txs ghosts to 0_ff f005 a2 5d ldx 5d clear memory f007 20 bd f5 jsr f5bd 00 through a2 hardware registers and game variables f00a a9 10 lda 10 console switches are all f00c 8d 83 02 sta swbcnt inputs d4 is not used f00f 85 88 sta m88 is this the debounce f011 20 a3 f1 jsr f1a3 main game loop main f014 20 32 f0 jsr starttvframe start the next tv frame f017 20 57 f1 jsr f157 switches f01a 20 72 f5 jsr f572 pro switches f01d 20 da f2 jsr f2da f020 20 44 f4 jsr f444 collisions f023 20 14 f2 jsr f214 f026 20 a9 f2 jsr f2a9 f029 20 f2 f1 jsr scoregraphics convert the player scores to graphics offsets f02c 20 54 f0 jsr drawvisible draw the screen f02f 4c 14 f0 jmp main back to top of main loop start the tv frame starttvframe increment the frame counter and trigger the vertical sync the timer is set to time the blanking period f032 e6 86 inc framecounter bump the frame counter f034 85 2b sta hmclr clear horizontal motion registers f036 a9 02 lda 02 d1 bit on f038 85 02 sta wsync wait for the end of the current line f03a 85 01 sta vblank turn the electron beam off f03c 85 02 sta wsync wait for all f03e 85 02 sta wsync the electrons f040 85 02 sta wsync to drain out f042 85 00 sta vsync trigger the vertical sync signal f044 85 02 sta wsync hold for f046 85 02 sta wsync two scan lines f048 a9 00 lda 00 d1 bit off f04a 85 02 sta wsync hold for a third line f04c 85 00 sta vsync release the vertical sync signal f04e a9 2b lda 2b set timer to 43 64 2752 machine f050 8d 96 02 sta tim64t cycles 2752 228 3 36 scanlines f053 60 rts done draw the visible screen drawvisible todo blurb on frame 30 and the key f054 a9 20 lda 20 start counting at 32 f056 85 b4 sta scanlinenumber makes the playfield math easier f058 85 02 sta wsync wait for the end of the current line ensure hmove is in the horiz blanking f05a 85 2a sta hmove apply horizontal movement to all objects f05c ad 84 02 lda intim wait for the visible tv to f05f d0 fb bne f05c reach the visible area f061 85 02 sta wsync 37th scanline f063 85 2c sta cxclr clear the collision flags f065 85 01 sta vblank turn the electron beam back on f067 ba tsx save stack f068 86 d3 stx stackpointer pointer f06a a9 02 lda 02 playfield left right color of p0 p1 f06c 85 0a sta ctrlpf on top f06e a6 dc ldx mdc f070 85 02 sta wsync f072 ca dex f073 d0 fb bne f070 f075 a5 dc lda mdc f077 c9 0e cmp 0e f079 f0 52 beq f0cd skip drawing the top numbers f07b a2 05 ldx 05 5 rows per digit f07d a9 00 lda 00 clear f07f 85 de sta nextleft next pattern for left two digits f081 85 df sta nextright clear next pattern for right two digits loop for drawing digits from z26 log for frame 30 lines 42 through 53 42 at f083 loop from f083 to f0ca 43 1 1 first pass blanks 44 1 1 digit row 1 45 1 1 duplicate row 1 46 1 1 digit row 2 47 1 1 duplicate row 2 48 1 1 digit row 3 49 1 1 duplicate row 3 50 1 1 digit row 4 51 1 1 duplicate row 4 52 1 1 digit row 5 53 1 1 duplicate row 5 54 1 1 digit aborted at f0cd f083 85 02 sta wsync 42 21 hard_wsync wait for next row f085 a5 de lda nextleft 43 0 ram_nextleft digit graphics calculated last row f087 85 0e sta pf1 43 3 hard_pf1 duplicate the left number from last row f089 a4 e2 ldy leftdigitmsd 43 6 ram_leftdigitmsd index to left number left digit f08b b9 c5 f5 lda f5c5 y 43 9 get graphics for digit f08e 29 f0 and f0 43 13 only the left part of the pattern f090 85 de sta nextleft 43 15 ram_nextleft new graphics for left number f092 a4 e0 ldy leftdigitlsd 43 18 ram_leftdigitlsd index to left number right digit f094 b9 c5 f5 lda f5c5 y 43 21 get graphics for digit f097 29 0f and 0f 43 25 only the right part of the pattern f099 05 de ora nextleft 43 27 ram_nextleft combine left and right digits f09b 85 de sta nextleft 43 30 ram_nextleft we ll use it next row f09d a5 df lda nextright 43 33 ram_nextright digit graphics calculated last row f09f 85 0e sta pf1 43 36 hard_pf1 duplicate the right number from last row f0a1 a4 e3 ldy rightdigitmsd 43 39 ram_rightdigitmsd index to right number left digit f0a3 b9 c5 f5 lda f5c5 y 43 42 get graphics for digit f0a6 29 f0 and f0 43 46 only the left part of the pattern f0a8 85 df sta nextright 43 48 ram_nextright new graphics for right number f0aa a4 e1 ldy rightdigitlsd 43 51 ram_rightdigitlsd index to the right number right digit f0ac b9 c5 f5 lda f5c5 y 43 54 get graphics for digit f0af 25 87 and maskrightnumber 43 58 ram_maskrightnumber blank the right number right digit if in game select f0b1 85 02 sta wsync 43 61 hard_wsync wait for next row f0b3 05 df ora nextright 44 0 ram_nextright combine left and right digits f0b5 85 df sta nextright 44 3 ram_nextright we ll use it later on this row f0b7 a5 de lda nextleft 44 6 ram_nextleft get the newly calculated graphics f0b9 85 0e sta pf1 44 9 hard_pf1 draw the new left number f0bb ca dex 44 12 all digit rows done f0bc 30 0f bmi f0cd 44 14 yes done on the last row we write a bogus value for the first number but we quickly clear it out at f0cd before it gets drawn f0be e6 e0 inc leftdigitlsd 44 16 ram_leftdigitlsd next row in left digit lsd f0c0 e6 e2 inc leftdigitmsd 44 21 ram_leftdigitmsd next row in left digit msd f0c2 e6 e1 inc rightdigitlsd 44 26 ram_rightdigitlsd next row in right digit lsd f0c4 e6 e3 inc rightdigitmsd 44 31 ram_rightdigitmsd next row in right digit msd f0c6 a5 df lda nextright 44 36 ram_nextright get the newly calculated graphics f0c8 85 0e sta pf1 44 39 hard_pf1 draw the right number f0ca 4c 83 f0 jmp f083 44 42 back for all rows of digits draw the play area f0cd a9 00 lda 00 54 17 clear the score for f0cf 85 0e sta pf1 54 19 hard_pf1 next row f0d1 85 02 sta wsync 54 22 hard_wsync make a blank line 55 w c c f0d3 a9 05 lda 05 55 0 playfield over players and f0d5 85 0a sta ctrlpf 55 2 hard_ctrlpf 55 2 reflect playfield f0d7 a5 d6 lda colorp0 55 5 ram_colorp0 55 5 set color f0d9 85 06 sta colup0 55 8 hard_colup0 55 8 player 0 f0db a5 d7 lda colorp1 55 11 ram_colorp1 55 11 set color f0dd 85 07 sta colup1 55 14 hard_colup1 55 14 player 1 top of loop same loop for the rest of the screen but at 155 we are in the middle of the screen where the players are let s pick up the video timing at the top of the loop midway across the scanline 155 155 156 x u t y 157 0 1 2 using the stackpointer here to speed up the writes we start pointing to enam1 and work lower in memory this is the playing area where the players and missiles are f0df a2 1e ldx 1e 155 42 pointer to f0e1 9a txs 155 44 enam1 player 0 f0e2 38 sec 155 46 clear the borrow flag f0e3 a5 a4 lda player0row 155 48 ram_player0row player 0 s row number f0e5 e5 b4 sbc scanlinenumber 155 51 ram_scanlinenumber compare it to the current row to speed up the lookup the players graphics are interleaved even rows are for player 0 and odd rows are for player 1 f0e7 29 fe and fe 155 54 even is for player 0 f0e9 aa tax 155 56 hold the graphics pointer f0ea 29 f0 and f0 155 68 within the 16 row window f0ec f0 04 beq f0f2 155 60 yes draw the player f0ee a9 00 lda 00 no player 0 graphics on this row f0f0 f0 02 beq f0f4 jmp f0f4 f0f2 b5 bd lda playerxpicture x 155 63 ram_playerxpicture 155 63 get the graphics for this row f0f4 85 02 sta wsync 155 67 hard_wsync 155 67 wait for next row f0f6 85 1b sta grp0 156 0 hard_grp0 156 0 draw player 0 on this row missile 1 f0f8 a5 a7 lda missile1row 156 3 ram_missile1row missile 1 row f0fa 45 b4 eor scanlinenumber 156 6 ram_scanlinenumber compare it to the current row f0fc 29 fe and fe 156 9 odd and even rows doubling the z flag is in the d1 position of the status register this maps to d1 of the enable missile 1 thus when the current row is the same as the missile the z flag will be set and will enable the missile with the push f0fe 08 php 156 11 turn missile 1 on or off missile 0 f0ff a5 a6 lda missile0row 156 14 ram_missile0row missile 0 row f101 45 b4 eor scanlinenumber 156 17 ram_scanlinenumber compare it to the current row f103 29 fe and fe 156 20 odd and even rows doubling f105 08 php 156 22 turn missile 0 on or off playfield graphics pointers the playfield pattern is a table of 12 entries this loop runs the table forwards with each entry drawn over 8 rows 8 12 96 rows then the loop runs the table backwards with each entry drawn over 8 rows 96 rows again the bottom of the screen reflects the top the reflection happens with the upper bit of the row count in b4 positive values are the upper half of the screen negative values are the lower half the number 12 as in twelve entries is difficult to work with but 16 is easy the math assumes the table is 16 values and starts with the fourth value the loop uses entries 4 16 on the positive top half then 16 4 on the bottom half the graphics pointers are backed up 4 bytes so that the table looks like 16 bytes b4 starts at 32 32 8 4 at the top half of the screen in the bottom half the check at f10c keeps the code from drawing the bogus values in the table entries 3 2 1 and 0 f106 a5 b4 lda scanlinenumber 156 25 ram_scanlinenumber current row f108 10 02 bpl f10c 156 28 we are in the top non reflected region b4 is 80 scanline 152 f10a 49 f8 eor f8 156 30 reflection run the table backwards from 15 f10c c9 20 cmp 20 156 32 at the bottom of the screen just use f10e 90 04 bcc f114 156 34 the last pattern over and over playfield graphics are 8 rows tall f110 4a lsr a 156 36 divide f111 4a lsr a 156 38 by f112 4a lsr a 156 40 8 each playfield value covers 8 rows f113 a8 tay 156 42 graphics offset to y for later f114 a5 a5 lda player1row 156 44 ram_player1row player 1 s row number f116 38 sec 156 47 clear the borrow flag this is how 6502 works f117 e5 b4 sbc scanlinenumber 156 49 ram_scanlinenumber compare the row numbers f119 e6 b4 inc scanlinenumber 156 52 ram_scanlinenumber bump to next row doubling f11b ea nop 156 57 timing f11c 09 01 ora 01 156 59 odd is for player 1 f11e aa tax 156 61 hold the graphics pointer f11f 29 f0 and f0 156 63 within the 16 row window f121 f0 04 beq f127 156 65 yes draw the player f123 a9 00 lda 00 no player 1 graphics on this row f125 f0 02 beq f129 jmp f129 f127 b5 bd lda playerxpicture x 156 68 ram_playerxpicture get the graphics for this row f129 24 82 bit skipplayfield 156 72 ram_skipplayfield bit 7 goes to the m flag f12b 85 1c sta grp1 156 75 hard_grp1 draw player 1 on this row f12d 30 0c bmi f13b 157 2 if d7 of 82 is set skip the playfield f12f b1 b5 lda pf0graphics y 157 4 ram_pf0graphics copy the f131 85 0d sta pf0 157 9 hard_pf0 pf0 graphics f133 b1 b7 lda pf1graphics y 157 12 ram_pf1graphics copy the f135 85 0e sta pf1 157 17 hard_pf1 pf1 graphics f137 b1 b9 lda pf2graphics y 157 20 ram_pf2graphics copy the f139 85 0f sta pf2 157 25 hard_pf2 pf2 graphics f13b e6 b4 inc scanlinenumber 157 28 ram_scanlinenumber next row we are doing 2 at a time f13d a5 b4 lda scanlinenumber 157 33 ram_scanlinenumber have we done all f13f 49 ec eor ec 157 36 236 rows f141 d0 9c bne f0df 157 38 no go back for more end of frame 258 x u t y 259 0 1 2 t u x y x 0 1 2 see the x y x on this last line why clear the grp0 twice f143 a6 d3 ldx stackpointer 259 33 ram_stackpointer restore the f145 9a txs 259 36 stack pointer we just eored with ec 11101100 and checked for zero the only way we get a zero is when a ec which means d1 is zero for the stores below f146 85 1d sta enam0 259 38 hard_enam0 turn off missile 0 f148 85 1e sta enam1 259 41 hard_enam1 turn off missile 1 f14a 85 1b sta grp0 259 44 hard_grp0 turn off player 0 f14c 85 1c sta grp1 259 47 hard_grp1 turn off player 1 f14e 85 1b sta grp0 259 50 hard_grp0 turn off player 0 why again f150 85 0d sta pf0 259 53 hard_pf0 turn off playfield 0 f152 85 0e sta pf1 259 56 hard_pf1 turn off playfield 1 f154 85 0f sta pf2 259 59 hard_pf2 turn off playfield 2 f156 60 rts 259 62 done called from main loop f157 ad 82 02 lda swchb console switches f15a 4a lsr a reset switch to carry f15b b0 13 bcs f170 1 means not pressed skip f15d a9 0f lda 0f no longer blanking f15f 85 87 sta maskrightnumber the right digit for p1 score f161 a9 ff lda ff f163 85 88 sta m88 f165 a9 80 lda 80 f167 85 dd sta mdd f169 a2 e6 ldx e6 f16b 20 bd f5 jsr f5bd f16e f0 60 beq f1d0 jmp f1d0 f170 a0 02 ldy 02 f172 a5 dd lda mdd f174 25 88 and m88 f176 c9 f0 cmp f0 f178 90 08 bcc f182 f17a a5 86 lda framecounter f17c 29 30 and 30 f17e d0 02 bne f182 f180 a0 0e ldy 0e f182 84 dc sty mdc f184 a5 86 lda framecounter f186 29 3f and 3f f188 d0 08 bne f192 f18a 85 89 sta m89 f18c e6 dd inc mdd f18e d0 02 bne f192 f190 85 88 sta m88 f192 ad 82 02 lda swchb console switches f195 29 02 and 02 select pressed f197 f0 04 beq f19d 0 means yes f199 85 89 sta m89 f19b d0 54 bne f1f1 jmp f1f1 f19d 24 89 bit m89 f19f 30 50 bmi f1f1 f1a1 e6 80 inc m80 called before main loop initialization f1a3 a2 df ldx df f1a5 20 bd f5 jsr f5bd f1a8 a9 ff lda ff f1aa 85 89 sta m89 f1ac a4 80 ldy m80 f1ae b9 d8 f7 lda f7d8 y f1b1 85 a3 sta ma3 f1b3 49 ff eor ff f1b5 d0 04 bne f1bb f1b7 a2 dd ldx dd f1b9 d0 ea bne f1a5 f1bb a5 81 lda m81 f1bd f8 sed f1be 18 clc f1bf 69 01 adc 01 f1c1 85 81 sta m81 f1c3 85 a1 sta scorep1 f1c5 d8 cld f1c6 24 a3 bit ma3 f1c8 10 06 bpl f1d0 f1ca e6 85 inc m85 f1cc 50 02 bvc f1d0 f1ce e6 85 inc m85 f1d0 20 25 f5 jsr f525 f1d3 a9 32 lda 32 f1d5 85 a5 sta player1row f1d7 a9 86 lda 86 f1d9 85 a4 sta player0row f1db 24 a3 bit ma3 f1dd 30 12 bmi f1f1 f1df 85 a5 sta player1row f1e1 85 11 sta resp1 resp1 28 11 f1e3 a9 08 lda 08 f1e5 85 96 sta m96 f1e7 a9 20 lda 20 f1e9 85 20 sta hmp0 hmp0 29 12 f1eb 85 21 sta hmp1 hmp1 29 12 f1ed 85 02 sta wsync wsync 29 12 f1ef 85 2a sta hmove hmove 30 13 f1f1 60 rts scoregraphics convert the score values in a1 to 5 byte digit offsets in e0 e2 convert the score values in a2 to 5 byte digit offsets in e1 e3 f1f2 a2 01 ldx 01 loop over 1 and 0 score for each player f1f4 b5 a1 lda scorep1 x get score f1f6 29 0f and 0f just the lower digit f1f8 85 d2 sta scratch1 we will add this back to make 5 f1fa 0a asl a digit 2 f1fb 0a asl a digit 4 f1fc 18 clc no carry f1fd 65 d2 adc scratch1 digit 5 f1ff 95 e0 sta leftdigitlsd x store offset f201 b5 a1 lda scorep1 x get score again f203 29 f...