RAM Usage

Work RAM lives at `0x0000`–`0x07FF`. 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
0000	gameMode	Current game-mode/state code that drives the mode dispatch and is armed from the pending mode
0001	modeDispatchSel	Pre-doubled selector paired with the mode byte; indexes the main-loop trampoline handler table
0002	gameModePending	Pending game mode promoted into GAME_MODE once the mode-delay timer expires
0003	frameCounter	Per-update frame counter; its low bits are the animation/even-odd phase read across the draw code
0004	modeDelayTimer	Delay countdown that gates promotion of the pending mode into the live mode
0005	statusFlags	Game status flag byte; bit7 = play/active state, other bits gate scoring, sound and draw paths
0006	phaseCounter	Phase/step counter drained by the setup step and clamped to 0x28 for a packed on-screen readout
0007	irqSubtimer	Software sub-timer incremented each interrupt; its wrap drives the TIMER1_LO/TIMER2_LO carry cascades
0008	inputPortLatch	Latched raw input port snapshot whose bits gate the three heartbeat lanes
0009	dsw1Snapshot	Snapshot of option/coinage port DSW1_COINAGE (bit1 toggled), read for configuration and increments
000a	dsw2Snapshot	Snapshot of option port DSW2_OPTIONS, sliced three ways into DIP configuration tables
000c	soundStepGate	Flag enabling the periodic sound-register sub-step in the per-frame dispatcher
000d	laneWrapPos	Three-lane wrapped position accumulator (masked to five bits) advanced by the heartbeat
0010	laneDowntimer	Per-lane down-timer (reloads to 0x78) that drives the heartbeat accumulator step
0013	laneCounter	Three-entry per-lane counter advanced by the heartbeat; its bit7 feeds the coin/LED latch
0014	laneCounter1	Second entry of the three-lane heartbeat counter (LANE_COUNTER base)
0015	laneCounter2	Third entry of the three-lane heartbeat counter (LANE_COUNTER base)
0016	heartbeatAccumLo	Low byte of the heartbeat running accumulator advanced with a carry link
0017	heartbeatAccumHi	High byte of the heartbeat running accumulator, later reduced by a table amount
0018	heartbeatAccumOverflow	Overflow tally advanced when the heartbeat accumulator subtraction stays non-negative
0019	levelGeomLo	Eight-entry working table of the current level's low geometry nibbles (mirrored to colour RAM COLOR_RAM)
0021	levelGeomHi	Eight-entry working table of the current level's high geometry nibbles (mirrored to colour RAM COLOR_RAM_8)
0022	colorCycle0	First entry of a three-entry array mirrored into colour RAM COLOR_RAM_9..COLOR_RAM_B
0023	colorCycle1	Second entry of the three-entry array mirrored into colour RAM COLOR_RAM_9..COLOR_RAM_B
0024	colorCycle2	Third entry of the three-entry array mirrored into colour RAM COLOR_RAM_9..COLOR_RAM_B
002c	coordListPtrLo	Low byte of the current coordinate-list / working indirect pointer pair
002d	coordListPtrHi	High byte of the current coordinate-list / working indirect pointer pair
0033	mathboxSignX	Sign flag of the horizontal (X) delta fed to the math box, controlling the X offset fold
0034	mathboxSignY	Sign flag of the vertical (Y) delta fed to the math box, controlling the Y offset fold
0035	savedIndex	Scratch that preserves a caller loop/slot index (X or Y) across a subroutine call
0036	savedIndex2	Second index-save scratch preserving a caller loop/slot index across a call
0037	slotLoopIndex	Current slot/column loop index driving the per-slot draw and update walks
0038	tableCursor	Secondary table/packed-record cursor and working-slot index used by the draw and projection passes
003a	wellDepthRow	Depth-row index into the well depth table SLOT_THRESHOLD_TABLE while drawing the playfield well rows
003b	workPtrLo	Low byte of a general working indirect pointer (source/glyph/shape-list/destination pointer)
003c	workPtrHi	High byte of the general working indirect pointer paired with WORK_PTR_LO
003e	activeSlotCount	Upper loop bound / active slot-or-channel count used by the per-slot scans
003f	levelId	Current/target level id compared against the last-seen level to trigger level setup
0046	playerLevelTbl	Per-slot table of level/progress values indexed by loc_3d; feeds the level cell loc_9f
0048	slotCountdown	Per-slot countdown/counter table indexed by loc_3d, decremented by the pacing tick
0049	slotCountdownHi	High/paired partner of the SLOT_COUNTDOWN slot countdown, spent together with it
004d	inputDebounced	Debounced held-input byte built from this and last frame's samples
004e	inputEdgeFlags	Newly-pressed input edges plus control/gate bits consumed by the frame steppers
004f	inputPrev	Previous-frame held-input snapshot used to detect rising edges
0050	spinnerAccum	Accumulated spinner delta (rotary encoder) read as the manual rim-rotation input
0051	rimRotOffset	Stored fine rim-rotation offset/velocity folded into the coarse angle each update
0052	spinnerPotPrev	Previous inverted spinner pot reading used to form the per-interrupt delta
0053	irqHeartbeat	Interrupt heartbeat counter; the main loop waits for it to reach nine as its frame boundary
0055	drawStyle	Style/colour selector byte staged for the object-record draw builder
0056	projPtY	Vertical (Y) coordinate operand fed to the math-box projection
0057	objDepth	Current object/segment depth (Z) value gated and projected by the draw pipeline
0058	projPtX	Horizontal (X) coordinate operand fed to the math-box projection
0059	clampTally	Clamp/run tally counter for the rim-segment and lane-sweep builders
005a	runSize	Run-size/count field for the rim-segment builder and the style pair
005b	depthLo	Low byte of the 16-bit well-depth / countdown-clock value, also a draw guard flag (bit7)
005c	depthAccumLo	Low byte of a secondary depth accumulator stepped alongside DEPTH_HI
005d	depthTarget	Target depth reseeded into the position high byte when the depth window collapses
005e	projYRef	Vertical (Y) reference/base subtracted from the point Y in the projection
005f	depthHi	High byte of the 16-bit well-depth / countdown-clock and the reference depth for object gating
0060	projXRef	Horizontal (X) reference/base subtracted from the point X in the projection
0061	projYLo	Low byte of the projected vertical (Y) accumulator / working coordinate block
0062	projYHi	High byte of the projected vertical (Y) accumulator
0063	projXLo	Low byte of the projected horizontal (X) accumulator / working coordinate block
0064	projXHi	High byte of the projected horizontal (X) accumulator
0066	projOfsYLo	Low byte of the vertical (Y) offset folded into the projected Y accumulator
0067	projOfsYHi	High byte of the vertical (Y) projection offset paired with PROJ_OFS_Y_LO
0068	projOfsXLo	Low byte of the horizontal (X) offset folded into the projected X accumulator (also a 24-bit total low byte)
0069	projOfsXHi	High byte of the horizontal (X) projection offset paired with PROJ_OFS_X_LO
006a	prevYLo	Low byte of the cached previous-point Y, subtracted by stroke-delta drawing
006b	prevYHi	High byte of the cached previous-point Y
006c	prevXLo	Low byte of the cached previous-point X, subtracted by stroke-delta drawing
006d	prevXHi	High byte of the cached previous-point X
006e	vecDeltaYLo	Low byte of the sign-extended vertical (Y) delta pair emitted as a vector stroke
006f	drawDeltaAHi	high byte of the first 16-bit coordinate delta of a vector record
0070	drawDeltaBLo	low byte of the second 16-bit coordinate delta of a vector record
0071	drawDeltaBHi	high byte of the second 16-bit coordinate delta of a vector record
0072	vgLastStat	cached last-emitted vector-generator state word, used to skip redundant emits
0073	vgRecordHeader	current vector-record header/opcode nibble byte
0074	drawCursorLo	low half of the vector display-list write pointer
0075	drawCursorHi	high half of the vector display-list write pointer
0076	drawCursorAltLo	low half of the alternate vector write pointer swapped with the main cursor
0077	drawCursorAltHi	high half of the alternate vector write pointer
0078	segSpreadALo	base of the 8-entry low-byte array of interpolated coordinate A along a segment
0079	segSpreadALo1	interpolated coordinate-A low byte, index 1 (also holds the clamped signed delta-A seed)
007a	segSpreadALo2	interpolated coordinate-A low byte, index 2
007b	segSpreadALo3	interpolated coordinate-A low byte, index 3
007c	segSpreadALo4	interpolated coordinate-A low byte, index 4
007d	segSpreadALo5	interpolated coordinate-A low byte, index 5
007e	segSpreadALo6	interpolated coordinate-A low byte, index 6
007f	segSpreadALo7	interpolated coordinate-A low byte, index 7
0080	segSpreadAHi	base of the 8-entry high-byte array of interpolated coordinate A
0081	segSpreadAHi1	interpolated coordinate-A high byte, index 1
0082	segSpreadAHi2	interpolated coordinate-A high byte, index 2 (doubles as the running fraction accumulator)
0083	segSpreadAHi3	interpolated coordinate-A high byte, index 3
0084	segSpreadAHi4	interpolated coordinate-A high byte, index 4
0085	segSpreadAHi5	interpolated coordinate-A high byte, index 5
0086	segSpreadAHi6	interpolated coordinate-A high byte, index 6
0087	segSpreadAHi7	interpolated coordinate-A high byte, index 7
0088	segSpreadBLo	base of the 8-entry low-byte array of interpolated coordinate B along a segment
0089	segSpreadBLo1	interpolated coordinate-B low byte, index 1 (also holds the clamped signed delta-B seed)
008a	segSpreadBLo2	interpolated coordinate-B low byte, index 2
008b	segSpreadBLo3	interpolated coordinate-B low byte, index 3
008c	segSpreadBLo4	interpolated coordinate-B low byte, index 4
008d	segSpreadBLo5	interpolated coordinate-B low byte, index 5
008e	segSpreadBLo6	interpolated coordinate-B low byte, index 6
008f	segSpreadBLo7	interpolated coordinate-B low byte, index 7
0090	segSpreadBHi	base of the 8-entry high-byte array of interpolated coordinate B
0091	segSpreadBHi1	interpolated coordinate-B high byte, index 1
0092	segSpreadBHi2	interpolated coordinate-B high byte, index 2 (doubles as the running fraction accumulator)
0093	segSpreadBHi3	interpolated coordinate-B high byte, index 3
0094	segSpreadBHi4	interpolated coordinate-B high byte, index 4
0095	segSpreadBHi5	interpolated coordinate-B high byte, index 5
0096	segSpreadBHi6	interpolated coordinate-B high byte, index 6
0097	segSpreadBHi7	interpolated coordinate-B high byte, index 7
0099	drawRecordCount	countdown of four-byte vector records still to emit in a run
009b	segDeltaASign	high/sign byte of the first signed segment delta
009d	segDeltaBSign	high/sign byte of the second signed segment delta
00a1	vgModeFlag	vector draw mode flag carrying bit 2 of the selected scale value
00a6	activeEnemyCount	count of live climbing enemies, also indexes the per-wave difficulty table
00a9	drawCursorOffset	byte offset added to the draw cursor for the current record run
00aa	drawSrcPtrLo	low half of an indirect source pointer read during draw-record building
00ab	drawSrcPtrHi	high half of the indirect draw source pointer
00ae	nibbleEmitCount	remaining byte count while emitting a run of zero-page bytes as nibbles
00af	nibbleEmitIndex	current zero-page source index for the nibble-run emitter
00b0	drawPatchPtrLo	low half of a saved record pointer used for a colour-patch second pass
00b1	drawPatchPtrHi	high half of the saved colour-patch record pointer
00b4	vgScale	selected vector-generator scale byte
00b5	checksumAcc	rolling checksum accumulator over a fixed ROM table
00b6	drawRecordPtrLo	low half of the pointer remembering where a display-list record began
00b7	drawRecordPtrHi	high half of the display-list record-start pointer
00bd	nvramScanPtrLo	low half of the pointer walking a region's RAM copy for the EAROM store/verify
00be	nvramScanPtrHi	high half of the EAROM region-copy walk pointer
00bf	soundSlotSentinel	index of the voice slot currently being claimed, holding the 0xff sentinel otherwise
00c0	soundVoiceValue	base of the 16-entry per-voice value/pitch table for the sound engine
00d0	soundVoiceLevel	base of the 16-entry per-voice level/output table published to POKEY
00e0	soundFastTimer	base of the 16-entry per-voice fast (frame-step) timer array
00f0	soundSlowTimer	base of the 16-entry per-voice slow (envelope) timer array
0104	spikeStepLo	low byte of the moving spike's 16-bit per-frame height increment
0105	spikeStepHi	high byte of the moving spike's 16-bit per-frame height increment
0106	spikeActiveFlag	moving-spike active/arm flag, active while bit7 set
0107	spikeHeightLo	low byte of the moving spike's 16-bit height (high byte in PLAYER_SHOT_DEPTH)
0108	enemyTotalCount	total live-enemy count decremented when no per-type count applies
0109	enemyTypeCount	per-type live-enemy count
010a	scriptWalkContinue	walk-continuation flag that keeps an object's driving script walk alive
010b	scriptCursor	rolling cursor naming the current position within the object script table
010c	scriptBranchFlag	flag recording the outcome of the most recent script test
010d	spawnFoundFlag	flag set when the spawn walk found a live or newly-spawned object
010e	spawnBudgetTimer	per-frame spawn budget countdown
0111	tubeGeomFlag	per-level tube-geometry flag; bit7 governs lane-index wrap and nonzero marks a live board
0112	tubeShapeIndex	current tube shape/level index used to index the level geometry tables
0114	redrawCounter	display-change counter bumped when watched state changes; also used as a 0xff dirty flag
0115	spikeTableGuard	Arm/guard flag for the descending spike object; its sign also chooses which rail the spike table snaps to
0116	timedObjectCount	Live-count / pending flag for the eight-slot timed-object table
0118	objectVelocityHi	High byte of the 16-bit per-frame velocity added to a far-slot object's position
0119	spawnTimerReload	Reload period written into a source slot's spawn timer after it fires
011a	flyerSlotTop	Top index for the free-flight destination-slot scan, clamped 0..3 by difficulty
011b	playerShapeSum	Running checksum of the 40-byte player-Blaster shape block, used as a draw/age gate
011c	enemySlotTop	Top index / count of the parallel per-slot enemy (climber) arrays
0120	objectVelocityLo	Low byte of the 16-bit per-frame velocity added to a far-slot object's position
0121	levelGeomScale	Per-level tube geometry scale, the signed delta driving the warp/zoom accumulator
0122	zoomAccumHi	High byte of the 24-bit warp/zoom position accumulator ZOOM_ACCUM_HI:PROJ_OFS_X_LO:PROJ_OFS_X_HI
0123	spikedSegmentCount	Tally of occupied/spiked segments around the tube, also carrying a per-frame bit7 flag
0124	rimColorAnim	Rim-lane colour-cycle animation counter, seeded on score award and decremented while drawing
0125	wavePhaseLatch	Wave/level-intro phase latch: set 0xff when the wave block is ready, gates staged sweeps
0126	wavePeakSeed	Peak-slot seed used to pick the wave start slot
0127	depthCeiling	Ceiling for the player depth window / wave start-depth index
0129	columnSpawnCap	Per-column maximum enemy count (5-entry table 0x129..0x12d) used to cap spawning
012e	columnEnemyTarget	Per-column target enemy count (base of a 5-entry table), source of the spawn deficit
0133	levelLayoutTrigger	One-shot level-layout flag gating the initial colour-RAM clear
0135	activeObjectCount	Live count for the near-rim / projectile object bank (SLOT_STATE / loc_2db slots)
0139	vecramTailCursorLo	Low byte of the 16-bit vector-RAM tail write cursor
013a	vecramTailCursorHi	High byte of the 16-bit vector-RAM tail write cursor
013b	objectAnimPhase	Animation phase index / priority head flag for the animated top-object
013c	objectAnimTimer	Sub-timer / ready flag paired with the object animation phase
013d	spawnDeficitC0	Column-0 entry of the five-column spawn-deficit table (0x13d..0x141)
013f	spawnDeficitC2	Column-2 entry of the five-column spawn-deficit table
0140	spawnDeficitC3	Column-3 entry of the five-column spawn-deficit table
0142	laneEnemyCount0	Column-0 entry of the per-column active-enemy counter table (0x142..0x146)
0143	laneEnemyCount1	Column-1 entry of the per-column active-enemy counter table
0144	laneEnemyCount2	Column-2 entry of the per-column active-enemy counter table
0145	laneEnemyCount3	Column-3 entry of the per-column active-enemy counter table
0146	laneEnemyCount4	Column-4 entry of the per-column active-enemy counter table
0147	enemyAnimDelta	Signed per-frame step folded into the enemy animation/oscillator accumulator
0148	enemyAnimAccum	Signed enemy animation/oscillator accumulator driving flip and draw style
0149	candidateLane0	First entry of the four-entry candidate-lane table used to pick a climber's lane
014a	candidateLane1	Second entry of the four-entry candidate-lane table
014f	spikeLaneMaskAcc	Working bit-mask accumulator of lanes with a mid-growth spike during the timer scan
0150	spikeLaneMaskOut	Published copy of the spike-lane occupancy bit-mask after the timer scan
0151	enemyBandThreshold0	Band-0 entry of the far-slot proximity/retire threshold table (0x151..0x155)
0152	enemyBandThreshold1	Band-1 entry of the far-slot proximity/retire threshold table
0153	enemyBandThreshold2	Band-2 entry of the far-slot proximity/retire threshold table
0154	enemyBandThreshold3	Band-3 entry of the far-slot proximity/retire threshold table
0155	enemyBandThreshold4	Band-4 entry of the far-slot proximity/retire threshold table
0156	bonusLifeInterval	DIP-selected bonus-life score interval used as the award threshold
0157	nearDepthThreshold	Depth threshold below which an enemy counts as near the rim / reverses direction
0158	dswBonusConfig	DIP-decoded bonus/award configuration byte seeding the per-slot award counter
0159	enemyFireSelect	Per-enemy fire/aim selector flag (bit6 chooses the segment-step direction)
015a	laneFillInit	Initial per-lane fill value written across the sixteen-entry lane table at wave setup
015b	initialActiveCount	Initial active-object/slot count for the wave, copied into FIRE_GATE
015d	listPtrHi	Held high-byte source for the list-setup pointer
015e	coordDispatchSel	Even selector byte halved to dispatch a coordinate/step helper
015f	enemyFireThreshold	POKEY-random threshold that gates whether an enemy fires this frame
0160	enemyClimbDeltaLo0	Segment-0 low byte of the per-segment enemy climb-speed delta table (0x160..0x164)
0161	enemyClimbDeltaLo1	Segment-1 low byte of the per-segment enemy climb-speed delta table
0162	enemyClimbDeltaLo2	Segment-2 low byte of the per-segment enemy climb-speed delta table
0163	enemyClimbDeltaLo3	Segment-3 low byte of the per-segment enemy climb-speed delta table
0164	enemyClimbDeltaLo4	Segment-4 low byte of the per-segment enemy climb-speed delta table
0165	enemyClimbDeltaHi0	Segment-0 high byte of the per-segment enemy climb-speed delta table (0x165..0x169)
0166	enemyClimbDeltaHi1	Segment-1 high byte of the per-segment enemy climb-speed delta table
0167	enemyClimbDeltaHi2	Segment-2 high byte of the per-segment enemy climb-speed delta table
0168	enemyClimbDeltaHi3	Segment-3 high byte of the per-segment enemy climb-speed delta table
0169	enemyClimbDeltaHi4	Segment-4 high byte of the per-segment enemy climb-speed delta table
016a	dswDifficulty	DIP-decoded difficulty/config byte; its low bits drive the enemy-speed rescale
016b	modeDelayGuard	Guard/flag holding a pending mode transition through a delay
016c	decimalModeFlag	Flag gating decimal (BCD) score arithmetic and a self-check byte
016d	listSelectFlags	Flags byte OR-folded into a list-setup pointer low byte
016e	scoreDisplayTimer	Countdown timer ticked while drawing the score / high-score display
01c6	earomBlankFlag	High-score EAROM blank flag: when nonzero the write path zeros each source cell (erase a region)
01c7	earomRegionPending	High-score EAROM region-pending bits (one per low bit) awaiting service
01c8	earomRegionDir	High-score EAROM per-region direction bits: set = write out, clear = read back in
01c9	pendingWorkFlags	Working flags byte: EAROM per-region checksum-fail result bits and geometry-rebuild request bits
01ca	earomMode	High-score EAROM step-machine mode/busy byte (0x80 write, 0x20 read, 0 idle)
01cb	earomPassCounter	High-score EAROM per-region pass counter
01cc	earomCursor	High-score EAROM RAM cursor stepping through a region's bytes
01cd	earomLimit	High-score EAROM region end/limit cursor (checksum position)
01ce	earomRegionMask	Single-region mask isolated from the pending bits for the current EAROM pass
01cf	earomChecksumAcc	Running checksum accumulator for the EAROM region read/write
01ff	highLevelMarker	Latched high-level marker copied from the level index when the level is deep enough
0200	playerSegment	Player Blaster rim segment (coarse rotation position / current lane)
0201	playerFineAngle	Player fine rotation offset with bit7 as the rotation/object-pending flag
0202	playerShotDepth	Shared depth position of the player shot down the tube (0x10 rim..
0203	objectIndexTable	Per-entry object index / segment nibble in the 64-entry object-record bank (0x203..0x242)
0223	objectAxis0Frac	Axis-0 position-fraction low byte in the free-flight three-axis object integrator
0243	objectRecordTable	64-entry object-record table: per-slot growth/spawn timer, also its kind byte and random tag
0263	objectAxis1Pos	Axis-1 whole-coordinate byte in the free-flight three-axis object integrator
027f	objectBand	Per-object attribute folded to a 3-bit band selecting the proximity/retire threshold
0283	enemySlotFlags	Per-enemy-slot state byte: nonzero while alive, low 3 bits = lane/segment kind, bit6 = side, bit7 = live
028a	enemySlotDir	Per-enemy-slot direction/state byte: bit7 = climb direction, bit6 = armed, low bits = kind
0291	enemyScriptCursor	per-slot saved motion-script cursor for the climbing-enemy slot
029f	enemyDepthLo	low byte of a climbing enemy's 16-bit tube-depth coordinate
02a3	enemyPos2	axis-2 integer coordinate of the free-flight spawn integrator
02a6	enemyTimer	per-slot countdown timer for a climbing enemy
02ad	targetSeg	per-slot target segment for the lane-spawn object bank
02b9	enemySegment	target segment/lane number of a climbing enemy
02c3	enemyVel1Lo	axis-1 velocity low byte of the free-flight spawn integrator
02cc	enemyPhase	per-slot phase counter / successor-segment heading
02d3	slotState	per-slot counter/occupied cell for the lane-spawn bank (0 = free)
02df	enemyDepth	high byte of an enemy's tube depth; nonzero marks the slot live
02e3	enemyVel0Lo	axis-0 velocity low byte of the free-flight spawn integrator
02f2	hitTally	per-slot active flag (0xff) and hit tally for the lane-spawn bank
02fa	shapeCoord	per-slot coordinate for the eight-slot shape draw bank
0302	shapeId	per-slot shape id for the eight-slot shape draw bank
0303	enemyVel2Lo	axis-2 velocity low byte of the free-flight spawn integrator
030a	shapeActive	per-slot active flag for the eight-slot shape draw bank (nonzero = drawn)
0312	shapeAnim	per-slot animation/age byte for the shape draw bank
031a	colValA	per-column geometry value (plane A) built at level setup
0323	enemyVel1Hi	axis-1 velocity high byte of the free-flight spawn integrator
032a	colSubA	per-column geometry sub/second byte paired with COL_VAL_A
033a	colValB	per-column geometry value (plane B) built at level setup
0343	enemyVel0Hi	axis-0 velocity high byte of the free-flight spawn integrator
034a	colSubB	per-column geometry sub/second byte paired with COL_VAL_B
035a	objDyHi	per-object Y-delta high byte
0363	enemyVel2Hi	axis-2 velocity high byte of the free-flight spawn integrator
036a	objDyLo	per-object Y-delta low byte
037a	objDxHi	per-object X-delta high byte
038a	objDxLo	per-object X-delta low byte
039a	laneTargetFlag	per-lane target flag (0xc0/0x80 marks a flagged lane)
03aa	sweepStage	stage/phase index for the sweep handler
03ab	fireGate	global gate that enables enemy fire
03ac	laneLimit	per-lane limit/threshold used by the hit/award scan
03ce	segBaseX	per-segment base X coordinate of the tube geometry
03de	segBaseY	per-segment base Y coordinate of the tube geometry
03ee	segDirection	per-segment ring-direction table
0406	timer1Lo	low byte of a software timer cascade ticked by the periodic interrupt
0407	timer1Mid	middle byte of the first software timer cascade
0408	timer1Hi	high byte of the first software timer cascade
0409	timer2Lo	low byte of a second software timer cascade
040a	timer2Mid	middle byte of the second software timer cascade
040b	timer2Hi	high byte of the second software timer cascade
040c	coordAccLo	low byte of a 16-bit coordinate accumulator
040d	coordAccHi	high byte of the 16-bit coordinate accumulator
040f	digitInLo	low byte of the digit builder's first input pair
0410	digitInHi	high byte of the digit builder's first input pair
0412	divQuotient	quotient cell seeded by the digit builder's divide
0413	divRemainder	remainder cell seeded by the digit builder's divide
0415	pointerParity	per-slot parity flag toggled to double-buffer pointer records
0425	laneFlags	sixteen-entry rim-lane flag/color block
0435	segMidX	per-segment midpoint X (average of adjacent segment bases)
0445	segMidY	per-segment midpoint Y (average of adjacent segment bases)
051e	sortPayloadLo	low byte of a per-row payload reordered by the buildSortedSoundRequest bubble sort
051f	sortPayloadMid	middle byte of the per-row payload reordered by the sort
0520	sortPayloadHi	high byte of the per-row payload reordered by the sort
0600	slotMetric	per-channel/slot count array
0602	activeSlot	current active-slot cursor for the arming driver
0603	requestBits	packed request word, two bits per slot, drained by the arming driver
0604	rearmCounter	step counter that re-arms the driver when it underflows
0605	passCounter	sort-pass counter / arming countdown
0606	slotValue	per-slot value block clamped to the 0x1a rail
061e	sortKeyLo	low byte of the per-row sort key
061f	sortKeyMid	middle byte of the per-row sort key
0620	sortKeyHi	high byte of the per-row sort key
0706	glyphParamX	per-slot glyph draw parameter (plane X)
0707	glyphParamY	per-slot glyph draw parameter (plane Y)
0708	glyphParamZ	per-slot glyph draw parameter (plane Z)
071e	inputSnapshotHi	change-detection latch of (DSW2_SNAPSHOT & 0xf8)
071f	inputSnapshotLo	change-detection latch of (DSW_DIFFICULTY & 0x03)