Main Board RAM

Work RAM lives at `0xA800`–`0xAFFF`. Each name below describes the cell by its role in the running game; the hex address is the stable identity. Cells that share a byte, or whose role is only partly pinned, carry a terse caveat.

Address	Name	Description
a800	playerState	State byte of the player's own record, which begins at this address.
a802	playerHeading	The heading the player's ship is flying, a full byte = 256 steps of the circle.
a808	worldScrollY	Per-frame world scroll, the component that lands in a sprite entry's NATIVE-Y byte.
a80a	worldScrollX	Per-frame world scroll, the component that lands in a sprite entry's NATIVE-X byte.
a810	actorRecordSlot0	Actor slot 0's record head -- first of the four actor/target object slots (array slots 1-4).
a811	waveKillCountdown	How many more qualifying kills until the current wave's shared claim fires.
a812	waveClaimTimer	Frame-countdown window during which a spawned wave's shared claim is armed.
a814	bankLaunchCooldownPeriod	Reload period (interval constant) that re-arms BANK_LAUNCH_COOLDOWN after a launch; never decremented.
a817	bankLaunchCooldown	Live per-vblank cooldown for the bank-launch arm (launchBankEnemyWhenAimedNearPlayer) and the Mother-Ship's homing spawn.
a820	actorRecordSlot1	Actor slot 1's record head.
a821	claimToken	The shared "last of the wave" token, holding one claimant at a time.
a827	bankLaunchNearHalfY	Near-band proximity half-width gating a bank launch, one axis.
a830	actorRecordSlot2	Actor slot 2's record head; also the free-slot-search band base.
a837	bankLaunchNearHalfX	The other-axis near-band proximity half-width for the bank launch (launchBankEnemyWhenAimedNearPlayer only; its local name calls it X).
a840	actorRecordSlot3	Actor slot 3's record head; also doubles as the aimed-spawn era "bank A" record seat.
a844	bankLaunchSlotCount	Count of records the bank-launch arm scans for a free slot (loop bound; zero disables the arm).
a850	craftRecordSlot0	Slot 0's record, and the iteration base of the whole 7-slot craft band.
a860	craftRecordSlot1	Slot 1's record head; its per-slot handler seats it and tails into the era body.
a870	craftRecordSlot2	Slot 2's record head.
a880	craftRecordSlot3	Slot 3's record head.
a890	craftRecordSlot4	Slot 4's record head, and the seat of the "cleared" free-slot spawn search.
a8a0	motherShipState	State byte of the Mother-Ship's record, which begins at this address and runs two slots.
a8a4	motherShipHoldCounter	Mother-Ship record +4 (the code's own alias is HOLD_COUNTER): a countdown decremented each mid-phase frame while the ship is kept live, reaching 0 ends the phase; zeroed on the player-contact kill.
a8b0	craftRecordSlot6	Slot 6's record head (the last ordinary craft slot), with two extra duties.
a8b4	motherShipAimSideToggle	The Mother-Ship's homing-launch aim-side toggle: inc'd each launch, bit 0 picks the +0x18 / -0x18 side of the aim.
a8c0	eraObjectRecordSlot0	Era-object bank slot 0's record head -- base of the three-slot per-era special-object bank (array 12-14).
a8c6	attackerSpawnSlotCount	Per-era count of enemy slots the attacker / craft-bank spawner fields -- §3's "spawner cap 0, 1, 2".
a8d0	eraObjectRecordSlot1	Era-object bank slot 1's record head (second of the grouped three).
a8d4	attackerSpawnAimSideToggle	The attacker (era-bank) aimed-spawn aim-side toggle: inc'd each spawn, bit 0 picks the +/- side of the aim window whose magnitude is ATTACKER_SPAWN_WINDOW_HALF (0xa8d6, this record's +6).
a8d6	attackerSpawnWindowHalf	Half-width of the proximity window deciding WHETHER the era attacker bank spawns (doubled into a window).
a8dc	hitsRemaining	How many more hits the big two-slot object can absorb before it dies.
a8e0	eraObjectRecordSlot2	Era-object bank slot 2's record head; also doubles as the aimed-spawn era "bank B" record seat.
a8e6	attackerSpawnAimWindowHalf	Half-width of the final launch-facing window for the attacker spawn.
a8f0	parachutistRecord	The parachutist's record head (array slot 15); its +7 is PARACHUTIST_RUNG 0xa8f7.
a8f4	attackerSpawnCooldown	Live shared per-vblank cooldown for the era attacker-bank spawn arms.
a8f6	attackerSpawnCooldownPeriod	Reload period (interval constant) for ATTACKER_SPAWN_COOLDOWN; never decremented.
a8f7	parachutistRung	How many rescue awards this life has already been paid, which is the rung the next one takes.
a900	sceneryRecordSlot0	Scenery record base, scenery slot 0 (array slot 16); the ix cursor runSceneryForEra seats (paired with SCENERY_ENTRY_SLOT0).
a97f	playerStateBlockEnd	inclusive top of the player/actor-state RAM block cleared from PLAYER_STATE on a fresh round
a980	frameTick	Free-running frame counter, advanced once per vblank service.
a981	coinAccepted	Coin-counter pulses the machine still OWES the mechanical counter.
a982	coinAcceptedSlot2	slot-2 twin of COIN_ACCEPTED (0xa981)
a983	serviceCreditDebounce	IN0 bit-2 debounce; a clean edge awards one credit (service-bit identity MAME-pending)
a984	coinPulseTimer	Pulses coin slot 1's mechanical counter still owes, counted down one frame at a time.
a985	coinPulseTimerSlot2	slot-2 twin of COIN_PULSE_TIMER (0xa984)
a986	creditCount	packed-BCD on-screen credit total (saturates at 0x99)
a987	screenUnflipped	Whether the picture is the right way up for whoever is playing: 1 upright, 0 turned round.
a988	blankLinesLeft	Lines of the character plane still to blank in the wipe now running.
a989	blankLineCursor	Where the next line of that wipe starts — a 16-bit cell address in the character plane.
a98d	highScoreHi	High score. HIGH_SCORE_HI is the MSB of the single displayed high score (0xA98B/8C/8D), seeded at boot and promoted when a game beats it.
a98e	fireButtonEdgeShift	Fire-button edge-detect shift register.
a991	scratchPtrA	General 16-bit scratch pointer (first of the pair, 0xA991-A992); dereferenced as a live working cursor, role varies by caller.
a993	scratchPtrB	General 16-bit scratch pointer (second of the pair, 0xA993-A994); sometimes used alone (e.g. as a video-write destination).
a99d	chainWindow	How much longer a hit still counts as part of the current chain.
a99e	chainStep	Which rung of the chained-hit award ladder the next hit will be paid at.
a9ab	sequencePhase	OUTER phase of the same two-level machine: the machine's top-level MODE.
a9ac	sequenceSubstep	INNER index of the two-level sequence machine.
a9ad	dip1Mirror	inverted mirror of DSW 0xC200 (the gameplay dip bank)
a9ae	in0Mirror	Mirror of the IN0 input port, rewritten every frame from the port itself.
a9af	in1Mirror	inverted mirror of IN1 0xC320 (main / player-1 controls)
a9b0	in2Mirror	inverted mirror of IN2 0xC340 (cocktail / player-2 controls)
a9b1	coinageSettings	The two coinage DIP settings, as the machine sees them: the complement of the DSW0 port.
a9b2	commandWriteCursor	SOUND: write index into the 64-cell command ring (pairs 0xa9b3)
a9b3	commandReadCursor	The command ring's CONSUMER cursor: which cell the foreground loop reads next.
a9c0	freePlay	Set while the cabinet is on free play, so a coin never has to buy a credit.
a9c1	startingLives	lives per game (3/4/5/0xff), loaded into PLAYER_ONE/TWO_LIVES at start
a9c2	cocktailMode	cabinet type; gates screen flip (exact polarity MAME-pending)
a9c3	bonusLifeSetting	selects the bonus-life mark list + the attract bonus captions
a9c4	difficultySetting	Which of the eight Difficulty DIP positions the cabinet is set to, 0-7.
a9c6	demoSoundsEnable	attract-sound gate: a queued request is dropped unless set or a game is active
a9c7	coinSlot1Debounce	slot-1 coin-line debounce shift register
a9c8	coinSlot1Accumulator	slot-1 coins-inserted accumulator (+0x10/coin vs COIN_SLOT_1_RATIO 0xa9c9)
a9c9	coinSlot1Ratio	What coin slot 1 charges: coins-required-minus-one in the high nibble, credits in the low.
a9ca	coinSlot2Debounce	slot-2 debounce (the idiomatic layer mislabels it "PHASE")
a9cb	coinSlot2Accumulator	slot-2 accumulator (+0x10/coin vs COIN_SLOT_2_RATIO 0xa9cc)
a9cc	coinSlot2Ratio	The same for coin slot 2, from the OTHER nibble.
a9cd	killQuota	The kill quota a round is armed with: how many enemies the next round will ask for.
a9ce	bcdFrameCounter	free-running packed-decimal frame counter (inc+daa each vblank)
a9cf	scriptCycleCounter	0..4 round-robin index for in-turn demo-script selection
a9d0	attractStageCounter	attract scene counter cycling 1->2->3->1
a9d3	startRungRounds15	The escalation rung a round STARTS on, for the first five rounds.
a9d4	startRungRounds610	The same, for rounds six to ten.
a9d5	startRungRounds11Up	The same, for round eleven and up.
a9d6	eraRungPeriod	How many wraps of the base-sixty counter one rung of ERA_RUNG lasts.
a9d7	eraRungTimer	Wraps of the base-sixty counter still to go before ERA_RUNG climbs again.
a9e2	penRouteLeg	Leg index into the pen's fixed L-shaped route table; incremented each run to select the next leg.
a9e3	penRowPos	The pen's row position as 8.8 fixed point (read as mem16 at 0xA9E3; its whole-cell high byte is PEN_ROW_CELL at 0xA9E4).
a9e4	penRowCell	The pen's whole-cell row -- the high byte of PEN_ROW_POS -- which plotPenCell masks to five bits and multiplies by the 32-cell row stride to address the plane.
a9e5	penColumnPos	The pen's column position as 8.8 fixed point (mem16 at 0xA9E5; whole-cell high byte PEN_COLUMN_CELL at 0xA9E6).
a9e6	penColumnCell	The pen's whole-cell column -- the high byte of PEN_COLUMN_POS -- added within the row by plotPenCell.
a9e7	penRowStep	Signed 8.8 per-step row increment ((target - PEN_ROW_POS)/16, sign kept), added to PEN_ROW_POS each step.
a9e9	penColumnStep	Signed 8.8 per-step column increment, added to PEN_COLUMN_POS each step.
a9eb	sequenceDelay	The sequence machine's shared one-shot delay: frames still to wait before its next step.
a9f0	introAnimationStep	The round-start intro animation's step selector (0..5): stepRoundStartIntroAnimation dispatches on it and each sub-animation writes the next step to hand off (flash->1, band-to-2->2, colour-cycle->3, band-to-4->4, flood->5).
a9f1	playerFlashTick	Frame tick of the player-ship white flash (intro step 0/1): bit 0 alternates the sprite colour; at tick 8 it advances INTRO_ANIMATION_STEP and requests the spawn-flash sound.
a9f2	bandTo2PassCountdown	Per-pass countdown for advanceScriptedCharPlaneBandTo2 (bit 0 selects a blank vs draw pass), decremented each pass and zeroed at the script's end, which sets INTRO_ANIMATION_STEP to 2.
a9f3	spriteColourCycleCountdown	Countdown driving a sprite's colour field during the colour-cycle step (bit 2 holds each colour four frames); advances INTRO_ANIMATION_STEP when it reaches zero, wrapping below zero.
a9f4	bandTo4PassCountdown	Per-pass countdown for advanceScriptedCharPlaneBandTo4 (bit 0 selects blank vs draw), zeroed at the script's end, which sets INTRO_ANIMATION_STEP to 4.
a9f6	colourFloodCountdown	Countdown stepped down once as floodColourPlaneWithSavedPlayerColour finishes painting the colour plane (intro step 4).
a9f7	bandScriptCursor	16-bit cursor walking the char-plane band script (a byte per plane cell); shared by the band-to-2 / band-to-4 drawers and stepThirteenScriptedGlyphCells, left where it ended.
aa10	playerEntry	The player's sprite entry (array slot 0's X-seat), and the iteration base of the whole entry band.
aa11	playerSpriteCode	The player's sprite code/shape byte = PLAYER_ENTRY +1; written from a heading-indexed table (the descriptor's 2nd byte).
aa12	actorEntrySlot0	Actor slot 0's sprite entry (paired with ACTOR_RECORD_SLOT0).
aa14	actorEntrySlot1	Actor slot 1's sprite entry.
aa16	actorEntrySlot2	Actor slot 2's sprite entry; free-slot-search entry seat.
aa18	actorEntrySlot3	Actor slot 3's sprite entry; also the aimed-spawn "bank A" entry seat.
aa1a	craftEntrySlot0	Slot 0's sprite entry, and the iteration base of the whole entry band; paired with CRAFT_RECORD_SLOT0 in every whole-band walk (entry stride +0x02).
aa1c	craftEntrySlot1	Slot 1's sprite entry (paired with CRAFT_RECORD_SLOT1).
aa1e	craftEntrySlot2	Slot 2's sprite entry.
aa20	craftEntrySlot3	Slot 3's sprite entry.
aa22	craftEntrySlot4	Slot 4's sprite entry, and the "cleared" spawn-search entry-cursor seat (parallel to CRAFT_RECORD_SLOT4).
aa24	motherShipEntry	The Mother-Ship's sprite entry (array slot 10), paired with MOTHER_SHIP_STATE 0xa8a0.
aa26	craftEntrySlot6	Slot 6's sprite entry: the "owed" spawn-search entry-cursor seat, and the Mother-Ship's second sprite entry when armed (parallel to CRAFT_RECORD_SLOT6).
aa28	eraObjectEntrySlot0	Era-object bank slot 0's sprite entry (paired with ERA_OBJECT_RECORD_SLOT0).
aa2a	eraObjectEntrySlot1	Era-object bank slot 1's sprite entry.
aa2c	eraObjectEntrySlot2	Era-object bank slot 2's sprite entry; also the aimed-spawn "bank B" entry seat.
aa2e	parachutistEntry	The parachutist's sprite entry (array slot 15), paired with PARACHUTIST_RECORD.
aa30	sceneryEntrySlot0	Scenery sprite-entry X seat, scenery slot 0 (array slot 16); base of publishSpriteShadow's bank-0 head run [.,6] (slots 16-18).
aa31	scenerySpriteCodeSlot0	Scenery sprite code/shape byte, scenery slot 0 (= SCENERY_ENTRY_SLOT0 +1); base of the era-keyed 8-slot code fill (stride 2).
aa36	sceneryEntrySlot3	Scenery sprite-entry X seat, scenery slot 3 (array slot 19); base of publishSpriteShadow's bank-0 tail run [.,10] (slots 19-23).
aa3f	tamperFoldFlag	work-RAM flag set 0xff before the image-signature fold, never read in the layer (foldImageBlockIntoSignatureThenAdvanceSequence)
aa40	playerSpriteAttribute	The player's sprite attribute byte (colour + flip bits), and the base of the second bank's 32-byte colour/flip run publishSpriteShadow copies to hardware.
aa41	playerSpriteY	The player's sprite Y (vertical) byte, and the base of the Y band hideAllSprites / hideCaptionSprites zero to park every sprite off-screen.
aa43	actorSpriteYSlot0	Actor slot 0's sprite Y (array slot 1; = ACTOR_ENTRY_SLOT0 +0x31, one step of the PLAYER_SPRITE_Y band).
aa55	motherShipSpriteY	The Mother-Ship's sprite Y (array slot 10; = MOTHER_SHIP_ENTRY +0x31); read as a scalar in the contact/collision windows.
aa59	eraObjectSpriteYSlot0	Era-object bank slot 0's sprite Y (array slot 12; = ERA_OBJECT_ENTRY_SLOT0 +0x31); read as a scalar in fixed-target collision.
aa60	scenerySpriteAttributeSlot0	Scenery attribute (colour+flip) band base, scenery slot 0 (= SCENERY_ENTRY_SLOT0 +0x30); base of the bank-1 head run [.,6].
aa66	scenerySpriteAttributeSlot3	Scenery attribute band, scenery slot 3 (array slot 19); base of publishSpriteShadow's bank-1 tail run [.,10].
aa6f	tamperImageSignature	The folded byte-signature of a program-image block (the self-check's checksum); written by the image-fold step and read once at ROM 0x2730 as cp 0x76, deraling to the power-on wipe on mismatch -- an anti-tamper cell.
aa80	playerShotArray	Base of the player's six-slot shot record array.
aa81	shotBurstPending	Countdown of shots still owed from the current fire press.
aa82	shotSpawnCooldown	Inter-shot fire-rate cooldown: frames left before the next player shot may seed.
aadf	playerShotArrayEnd	inclusive top of the player-shot RAM block cleared from PLAYER_SHOT_ARRAY on a fresh round
ab08	highScoreTableBase	The high-score TABLE is five records of eight bytes at 0xAB08..0xAB2F: per record +0 rank, +1..+3 score lo/mid/hi, +4..+7 name glyphs.
ab0b	highScoreRec0ScoreHi	The high-score TABLE is five records of eight bytes at 0xAB08..0xAB2F: per record +0 rank, +1..+3 score lo/mid/hi, +4..+7 name glyphs.
ab10	highScoreRec1Base	The high-score TABLE is five records of eight bytes at 0xAB08..0xAB2F: per record +0 rank, +1..+3 score lo/mid/hi, +4..+7 name glyphs.
ab18	highScoreRec2Base	The high-score TABLE is five records of eight bytes at 0xAB08..0xAB2F: per record +0 rank, +1..+3 score lo/mid/hi, +4..+7 name glyphs.
ab20	highScoreRec3Base	The high-score TABLE is five records of eight bytes at 0xAB08..0xAB2F: per record +0 rank, +1..+3 score lo/mid/hi, +4..+7 name glyphs.
ab27	highScoreSlideSrc	The high-score TABLE is five records of eight bytes at 0xAB08..0xAB2F: per record +0 rank, +1..+3 score lo/mid/hi, +4..+7 name glyphs.
ab28	highScoreRec4Base	The high-score TABLE is five records of eight bytes at 0xAB08..0xAB2F: per record +0 rank, +1..+3 score lo/mid/hi, +4..+7 name glyphs.
ab2f	highScoreTableEnd	The high-score TABLE is five records of eight bytes at 0xAB08..0xAB2F: per record +0 rank, +1..+3 score lo/mid/hi, +4..+7 name glyphs.
ab30	randomRegister	Base of the seventeen-byte shift register the pseudo-random generator advances.
ab43	tamperGlyphCopy	A copy of one character cell's glyph, taken so the anti-tamper machinery can check later that the display still says what it should.
abfe	tamperGlyphStrip	Anti-tamper caption witness -- the glyph sampled from a copyright-caption cell (0xA61C), re-checked each await-start frame by the animation strip (cp 0xa5); a mismatch diverts the strip's special path.
abff	tamperColourStrip	The colour byte of the TAMPER_GLYPH_STRIP sample (from the colour-RAM mirror); checked cp 0x05 / cp 0x10.
ac00	commandRing	The 64-cell command ring: command byte and argument byte in adjacent cells.
ac43	soundQueueCount	Count of queued sound-code bytes in the low-level sound FIFO; the enqueuer increments it, the drain decrements it (0 = empty).
ac44	soundQueueHead	Head (oldest byte) and base of the sound-code FIFO body; the drain sends it, then slides the remaining bytes down.
ac64	enemyAimAnchorY	The enemy aim ANCHOR point's paired coordinate byte -- the Y of the pair whose X is ENEMY_AIM_POINT_TABLE (0xAC65).
ac65	enemyAimPointTable	Base of the enemy aim-point table, and byte-wise entry 0's X = the ship anchor point (0xAC64 = Y).
ac74	enemyStandoffAimSetY	The SET standoff aim point's Y pair byte (its X is ENEMY_STANDOFF_AIM_SET at 0xAC75; names.js already documents "pair 0xAC74 = Y").
ac75	enemyStandoffAimSet	X byte of one of the two selectable ship-standoff aim points (pair 0xAC74 = Y).
ac79	enemyStandoffAimClear	X byte of the sibling standoff aim point (pair 0xAC78 = Y), chosen when that selector bit is CLEAR.
ac7f	enemyStandoffAimMain	X byte of the most-referenced ship-standoff aim point (pair 0xAC7E = Y).
ac83	enemyStandoffAimBlockEnd	The last byte (base + 0x0F) of that sixteen-byte aim-coordinate record; used only as the inclusive terminator of armRoundStart's 0x80 clear loop `cell <= 0xAC83`.
acc0	eraRung	The escalation rung inside the current era: the LOW half of the composite ERA_INDEX describes.
acc1	roundCraftCount	Per-round enemy-craft quota: how many craft a round should field.
acc2	waveSpawnBusyFlag	work-RAM busy/lock flag =0xff around the inline wave-build loop, =0 after (driveEnemyWaveForLifePhase)
acc3	waveDescriptorIndex	Descriptor-table selector for the current inline wave: (2 * era) + a random parity bit.
acc4	scriptPickThreshold	Per-round threshold that decides how each spawning craft's movement script is chosen.
acc6	roundTransitionHold	Nonzero while a round / wave / Mother-Ship transition sequence is underway.
acc7	tamperGlyphKonami	Anti-tamper caption witness -- the glyph sampled from the "(c) KONAMI 1982" caption cell 0xA63C ('N'); checked by the scenery/era arm as cp 0x3b, deraling into a data-run trap (0x315b) on mismatch.
ad00	livesRemaining	Lives the ACTIVE player has left, in the live context block.
ad01	roundNumber	Which round is being played, counting on without wrapping.
ad02	killsRemaining	Enemies still to destroy before the Mother-Ship appears -- the manual's 56.
ad03	bonusLifeLatch	Active context +3: the once-per-mark bonus-life award latch (bit 0); mirrors the saved PLAYER_ONE/TWO_BONUS_LIFE_LATCH.
ad04	eraIndex	Which era (the manual's ROUND) is being played, 0-4.
ad05	lifeTicksLow	Low place of a three-place base-sixty counter, stepped once per dispatch of the round engine's per-frame service block.
ad06	lifeTicksMid	Middle place of that counter, stepped once per wrap of LIFE_TICKS_LOW.
ad07	lifeTicksHigh	High place of that counter, stepped once per wrap of LIFE_TICKS_MID.
ad0a	startRung	Active context +0xA: the difficulty rung the round opens on (copied into ERA_RUNG 0xacc0 at reset); mirrors PLAYER_ONE/TWO_START_RUNG.
ad0b	penGlyph	The active caption/pen glyph (active context +0x0B, companion of PEN_COLOUR at +0x0C).
ad0c	penColour	The live caption/pen colour attribute (active context +0x0C; the saved per-player copies are at 0xAD1C/0xAD2C).
ad0d	motherShipArmed	Raised while this round's Mother-Ship has been armed.
ad0e	roundArmed	Active context +0xE: the round-armed gate (0xFF armed; cleared to 0 once the intro sound sequence completes); mirrors PLAYER_ONE/TWO_ROUND_ARMED.
ad10	playerOneLives	Player one's lives, in their saved sixteen-byte context block at 0xAD10.
ad11	playerOneRoundNumber	Player one's copy of ROUND_NUMBER (0xAD01), the unwrapped round ordinal. Seeded 1 at a fresh round arm; the attract arm overloads it to attract-stage + 1.
ad12	playerOneKillsRemaining	Player one's copy of KILLS_REMAINING (0xAD02): craft still to destroy this round, seeded from KILL_QUOTA (0xA9CD).
ad13	playerOneBonusLifeLatch	Player one's copy of the bonus-life award one-shot latch (active 0xAD03, bit 0, set by awardBonusLifeAtScoreMark once the score mark is passed).
ad14	playerOneEraIndex	Player one's copy of ERA_INDEX (0xAD04): which era/round is in force -- the key setSavedPenFromEra and seatCaptionPen use for the caption pen.
ad16	playerOneLifeTicksMid	Player one's copy of LIFE_TICKS_MID (0xAD06).
ad1a	playerOneStartRung	Player one's copy of the round start rung (active 0xAD0A) -- the difficulty rung the round opens on, later copied into ERA_RUNG.
ad1b	playerOnePenGlyph	Player one's saved copy of PEN_GLYPH (saved context +0x0B).
ad1c	playerOnePenColour	Player one's saved copy of PEN_COLOUR (saved context +0x0C); the source floodColourPlaneWithSavedPlayerColour reads when ACTIVE_PLAYER selects player one.
ad1d	playerOneMotherShipArmed	Player one's copy of MOTHER_SHIP_ARMED (0xAD0D).
ad1e	playerOneRoundArmed	Player one's copy of the round-armed gate (active 0xAD0E, which startNextRound sets to 0xFF and the ROM tests as a boolean `and a; ret z`).
ad20	playerTwoLives	Player two's lives, in their saved context block at 0xAD20 -- the same byte, the other block.
ad21	playerTwoRoundNumber	Player two's copy of ROUND_NUMBER -- the same field as PLAYER_ONE_ROUND_NUMBER, the other block.
ad22	playerTwoKillsRemaining	Player two's copy of KILLS_REMAINING; the twin of PLAYER_ONE_KILLS_REMAINING, seeded from KILL_QUOTA.
ad23	playerTwoBonusLifeLatch	Player two's copy of the bonus-life award latch; the twin of PLAYER_ONE_BONUS_LIFE_LATCH.
ad24	playerTwoEraIndex	Player two's copy of ERA_INDEX; the twin of PLAYER_ONE_ERA_INDEX (the caption-pen era key).
ad26	playerTwoLifeTicksMid	Player two's copy of LIFE_TICKS_MID; the twin of PLAYER_ONE_LIFE_TICKS_MID (mem16 clears the mid/high pair 0xAD26/0xAD27).
ad2a	playerTwoStartRung	Player two's copy of the round start rung; the twin of PLAYER_ONE_START_RUNG.
ad2b	playerTwoPenGlyph	Player two's saved copy of PEN_GLYPH; the twin of PLAYER_ONE_PEN_GLYPH, the other block.
ad2c	playerTwoPenColour	Player two's saved copy of PEN_COLOUR; the twin of PLAYER_ONE_PEN_COLOUR.
ad2d	playerTwoMotherShipArmed	Player two's copy of MOTHER_SHIP_ARMED; the twin of PLAYER_ONE_MOTHER_SHIP_ARMED.
ad2e	playerTwoRoundArmed	Player two's copy of the round-armed gate; the twin of PLAYER_ONE_ROUND_ARMED.
ad30	playActive	Flag set while play is active.
ad31	twoPlayerGame	Two-player-game flag: 0xFF for a two-player game, 0x00 for one player / attract.
ad32	activePlayer	Which of the two players is up: 0 for player one, 1 for player two.
ad33	player1ScoreLo	Scoring. Each player's score is three packed-BCD bytes, low byte first.
ad34	player1ScoreMid	Scoring. Each player's score is three packed-BCD bytes, low byte first.
ad35	player1ScoreHi	Scoring. Each player's score is three packed-BCD bytes, low byte first.
ad36	player2ScoreLo	Scoring. Each player's score is three packed-BCD bytes, low byte first.
ad37	player2ScoreMid	Scoring. Each player's score is three packed-BCD bytes, low byte first.
ad38	player2ScoreHi	Scoring. Each player's score is three packed-BCD bytes, low byte first.
ad39	tamperWitness	A character cell copied out of the display when the image checksum fails, glyph then colour.
adf2	demoScriptDwell	Attract-demo autopilot: the packed dwell/steer byte -- low 6 bits are the frame countdown, top 2 bits the steering command; reloaded from the next script byte when the dwell expires.
adf3	demoScriptPointerLo	Attract-demo autopilot: low byte of the little-endian cursor into the ROM heading-command script.
adf4	demoScriptPointerHi	Attract-demo autopilot: high byte of the DEMO_SCRIPT_POINTER_LO cursor.
adfb	tamperGlyphReadback	Tile-image tamper tripwire: the glyph read back from video cell 0xA5DC; the demo start derails into a data-run trap unless it reads 0xFD.
adfc	tamperColourReadback	Tile-image tamper tripwire: the colour read back from cell 0xA1DC; the demo proceeds only if it is 0x10 or 0x05.
ae00	deferredWriteCursor	Write pointer of the deferred character-write list, which runs from 0xAE04.
ae04	deferredWriteList	Head of the deferred-PAINT list -- 4-byte records {addr lo, addr hi, tile, colour} that DEFERRED_WRITE_CURSOR 0xae00 fills and paintDeferredCells drains into both planes; a cursor still == this head means the list is empty.
ae80	deferredBlankCursor	Write pointer of the SECOND deferred cell list, the one holding what to blank.
ae84	deferredBlankList	Head of the deferred-BLANK list (same 4-byte record layout) that DEFERRED_BLANK_CURSOR 0xae80 fills and blankCellsPaintedLastPass drains, stamping the blank glyph 0x20 into the character plane only.