Commodore 64 patterns.

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• A Bounded Event Queue on C64

  When three things happen before the game gets around to handling them, one event byte can only remember the last one.

  Commodore 64Framework · intermediateAssembly

• A Counted Text-entry Buffer on C64

  Entering a player name needs more than appending characters.

  Commodore 64Input · intermediateAssembly

• A game loop on the raster clock

  Wait for a fresh raster boundary, then read, update and draw. Keep timing separate from the work your game does.

  Commodore 64Framework · beginnerAssembly

• A Saturating 16-bit Score on C64

  A coin worth 300 points should still be worth 300 when the low byte fills up.

  Commodore 64Framework · intermediateAssembly

• A Streaming CRC-8 on C64

  A saved score or a small asset can pick up an accidental changed byte.

  Commodore 64Framework · intermediateAssembly

• Accept a Stable Run of Input Samples in C64 BASIC

  Change a logical byte only after enough consecutive identical samples, retaining candidate and run history.

  Commodore 64Input · intermediateBASIC

• Accumulate a Capped Binary Score in C64 BASIC

  Add two-byte awards through a wide intermediate, distinguish an exact cap from clipping and preserve the award.

  Commodore 64Framework · intermediateBASIC

• Action Cooldowns on C64

  Keep an action timer advancing between requests, and spend its cooldown only when a requested resource is available.

  Commodore 64Framework · intermediateAssembly

• Add and Remove Inventory Stacks on C64

  Picking up a stack should either fit completely or leave the inventory as it was.

  Commodore 64Framework · intermediateAssembly

• Add Signed Acceleration Without Wrapping in C64 BASIC

  Add a signed eight-point-eight velocity increment in a wider range, then clamp to an explicit symmetric limit before encoding the result.

  Commodore 64Physics · intermediateBASIC

• Add Words with Saturation on C64

  A large score or resource total should stop at its ceiling rather than wrap back to a small number.

  Commodore 64Framework · intermediateAssembly

• Advance a Timed Animation on C64

  A held pose and a running animation need different clocks.

  Commodore 64Rendering · intermediateAssembly

• Advance an Animation Timeline in C64 BASIC

  Return a frame index with configurable duration, looping and one-shot completion.

  Commodore 64Rendering · intermediateBASIC

• Aim a Projectile at a Target in C64 BASIC

  Compute a bounded two-component velocity towards a target with an explicit dominant-axis speed rule.

  Commodore 64Physics · intermediateBASIC

• Aim a Projectile with Bounded Integer Speed on C64

  A turret can fire towards the player without a trigonometry table or floating-point division.

  Commodore 64Physics · intermediateAssembly

• Allocate Slots with a Bitset on C64

  Eight occupied flags can fit in one byte when objects already live in fixed slots.

  Commodore 64Framework · intermediateAssembly

• Allocate Slots with an Occupied Mask in C64 BASIC

  Reserve the lowest free slot and release an occupied slot using one retained eight-bit mask.

  Commodore 64Framework · intermediateBASIC

• Apply Damage with Recovery Time in C64 BASIC

  Keep health above zero and give a hit a defined recovery interval, with explicit applied and killed results.

  Commodore 64Framework · intermediateBASIC

• Approach a Target Without Overshoot on C64

  An enemy can move towards a waypoint without orbiting it forever.

  Commodore 64Framework · intermediateAssembly

• Bounded Signed Acceleration on C64

  Gravity should keep adding speed until the chosen terminal velocity, not turn a fast fall into an upward launch when an integer overflows.

  Commodore 64Physics · intermediateAssembly

• Buffer Turns Through a Grid on C64

  A maze feels kinder when a turn pressed just before a junction happens as soon as the route opens.

  Commodore 64Framework · intermediateAssembly

• Build Bounded Spatial Buckets on C64

  Nearby objects are worth comparing; distant ones usually are not.

  Commodore 64Physics · intermediateAssembly

• Camera Dead Zones on C64

  A camera need not move every time the player takes a step.

  Commodore 64Physics · intermediateAssembly

• Capture and Restore a Checked Checkpoint on C64

  A restart point should restore a coherent snapshot, not whichever fields happened to be copied before a failed attempt.

  Commodore 64Framework · intermediateAssembly

• Carry a Passenger with a Platform in C64 BASIC

  Apply signed platform movement to a supported passenger, with explicit position bounds and clipping feedback.

  Commodore 64Physics · intermediateBASIC

• Carry a Supported Passenger on C64

  A passenger should inherit a moving platform’s displacement without changing the platform’s own position.

  Commodore 64Physics · intermediateAssembly

• Change Inventory Counts Atomically in C64 BASIC

  Add or remove a whole quantity from four fixed item categories, rejecting requests that exceed stock or capacity.

  Commodore 64Framework · intermediateBASIC

• Change Shared Character Pictures on C64

  Reusable install, replace and select routines for C64, with real code, native output and explicit video ownership.

  Commodore 64Rendering · intermediateAssembly

• Check a Byte Stream with CRC-8 in C64 BASIC

  Retain an eight-bit remainder while feeding a message byte by byte, with two explicit polynomial choices and a clear reset boundary.

  Commodore 64Framework · intermediateBASIC

• Choose a Bounded Text Line on C64

  A dialogue box needs line breaks that fit its width without requiring a second copy of the text.

  Commodore 64Framework · intermediateAssembly

• Choose a Winning Request in C64 BASIC

  Select the highest-priority request while keeping the first equal-priority winner and explicit batch ownership.

  Commodore 64Framework · intermediateBASIC

• Choose an Eight-way Direction on C64

  A character can face a target in eight directions without angles, trigonometry or a lookup table.

  Commodore 64Physics · intermediateAssembly

• Choose from Weighted Outcomes on C64

  A timid enemy might retreat often and attack rarely.

  Commodore 64AI · intermediateAssembly

• Choose Outcomes with Different Weights in C64 BASIC

  Map a caller-supplied bounded draw to one of eight weighted outcomes, skipping zero-weight entries.

  Commodore 64AI · intermediateBASIC

• Choose the Highest-priority Request on C64

  A pickup chime, a warning and an explosion may all request attention in one update.

  Commodore 64Framework · intermediateAssembly

• Clip a Rectangle to a View in C64 BASIC

  Find the visible intersection of two half-open rectangles, separating an empty result from invalid reversed edges.

  Commodore 64Physics · intermediateBASIC

• Clip a Rectangle to a Viewport on C64

  A partly off-screen object should expose only the part that lies inside the viewport.

  Commodore 64Physics · intermediateAssembly

• Commit a Crafting Recipe Atomically on C64

  Do not take the player’s ingredients and only then discover there is nowhere to put the result.

  Commodore 64Framework · intermediateAssembly

• Compact a Live Object Prefix on C64

  A particle update can walk a dense live prefix instead of checking holes forever.

  Commodore 64Framework · intermediateAssembly

• Compare Signed Byte Values on C64

  A velocity of −1 must sort below zero even though its stored byte is 255.

  Commodore 64Framework · intermediateAssembly

• Convert an Axis Sample to Intent in C64 BASIC

  Keep an inclusive quiet zone around a calibrated centre, then report direction and distance beyond it.

  Commodore 64Input · intermediateBASIC

• Count Active Play Ticks in C64 BASIC

  Keep a two-byte active counter, freeze it during pause and give reset explicit priority.

  Commodore 64Framework · intermediateBASIC

• Count Active Play Time on C64

  A pause screen should not quietly spend the player’s time allowance.

  Commodore 64Framework · intermediateAssembly

• Craft Without Losing Ingredients in C64 BASIC

  Check two ingredient stocks and result capacity before applying an all-or-nothing crafting transaction.

  Commodore 64Framework · intermediateBASIC

• Damage and Recovery on C64

  Apply damage without byte underflow, give an entity time to recover and emit one fatal-hit event.

  Commodore 64Framework · intermediateAssembly

• Debounce a Sampled Input Byte on C64

  A noisy or bouncing input should settle before it changes the game’s logical state.

  Commodore 64Input · intermediateAssembly

• Decode a Small Run-length Block in C64 BASIC

  Expand count/value pairs into an eight-cell output with explicit input bounds, actual written length and useful partial-error results.

  Commodore 64Framework · intermediateBASIC

• Decode Bounded Byte Deltas on C64

  A path or table whose values change slowly can be stored as a starting value followed by small signed differences.

  Commodore 64Framework · intermediateAssembly

• Decode Bounded RLE Data on C64

  Repeated tiles or pixels can be stored as a count followed by a value.

  Commodore 64Framework · intermediateAssembly

• Defer Object Changes Until After Traversal on C64

  Spawning or deleting objects during a traversal can accidentally update a new object twice or skip a neighbour.

  Commodore 64Framework · intermediateAssembly

• Detect a Button Chord Once on C64

  Holding two buttons together should trigger one action, not one action every frame.

  Commodore 64Input · intermediateAssembly

• Detect a Whole Button Chord Once in C64 BASIC

  Require a set of held buttons, exclude forbidden buttons and report a rising edge for the complete chord.

  Commodore 64Input · intermediateBASIC

• Divide a Word by a Byte on C64

  A quotient without its remainder throws useful information away.

  Commodore 64Framework · intermediateAssembly

• Divide Ticks Without Losing the Remainder on C64

  Thirty updates from fifty display ticks should be spaced out, not rounded down to zero.

  Commodore 64Framework · intermediateAssembly

• Draw Every Item Before Repeating the Bag in C64 BASIC

  Select and remove an item from a bounded bag, with explicit reset and caller-owned random indices.

  Commodore 64AI · intermediateBASIC

• Draw Objects in Stable Depth Order in C64 BASIC

  Sort object indices by depth without moving the objects, keeping equal-depth objects in their original order.

  Commodore 64Rendering · intermediateBASIC

• Draw Pixels, Spans and Boxes on C64

  Reusable 6502 drawing for the standard HIRES bitmap, with strict bounds, protected colour cells and byte masks.

  Commodore 64Rendering · intermediateAssembly

• Draw Without Repeating from a Bag on C64

  Random pieces can arrive in long droughts.

  Commodore 64AI · intermediateAssembly

• Edit a Counted Text Buffer in C64 BASIC

  Append a checked character, erase safely and clear a fixed eight-slot buffer while keeping live length separate from capacity.

  Commodore 64Input · intermediateBASIC

• Encode a Small Run-length Block in C64 BASIC

  Group up to eight byte values into count/value pairs, checking complete output capacity before changing any encoded byte.

  Commodore 64Framework · intermediateBASIC

• Encode a Small Run-length Block on C64

  Repeated map values can take less room as a count and a value—but only if the output buffer is big enough.

  Commodore 64Framework · intermediateAssembly

• Enter and Leave a Ladder on C64

  Climbing should suspend gravity, but jumping away must hand movement back to the ordinary player controller.

  Commodore 64Physics · intermediateAssembly

• Face a Target in Eight Directions in C64 BASIC

  Choose a discrete facing from two positions using signed displacement and a deliberate 2:1 sector rule.

  Commodore 64Physics · intermediateBASIC

• Fill a Connected Grid Region on C64

  A paint fill can also discover a connected room or reveal matching puzzle cells.

  Commodore 64AI · intermediateAssembly

• Filter Collision Pairs by Layer on C64

  A projectile can cross its owner without hitting them, while still hitting an opponent in the same patch of screen.

  Commodore 64Physics · intermediateAssembly

• Filter Collision Pairs by Policy in C64 BASIC

  Require mutual group acceptance, then classify an accepted pair as a sensor or solid before geometry testing.

  Commodore 64Physics · intermediateBASIC

• Find a Grid Path and Reachable Cells in C64 BASIC

  Return shortest four-neighbour distances, parents and a first step from a bounded tile map.

  Commodore 64AI · intermediateBASIC

• Find a Value in a Small Dictionary in C64 BASIC

  Search eight byte-key/value pairs, preserving the dictionary and returning the first match with separate found and validity flags.

  Commodore 64Framework · intermediateBASIC

• Find an Integer Square Root on C64

  Sometimes the useful answer is the whole-number distance, with no floating point in sight.

  Commodore 64Framework · intermediateAssembly

• Find the First Step Along a Shortest Grid Path on C64

  An enemy can walk around a wall without pretending that moving towards the player is already pathfinding.

  Commodore 64AI · intermediateAssembly

• Follow an Ordered Waypoint Route in C64 BASIC

  Move through four ordered positions, retaining the route cursor and choosing a loop or a finished one-shot.

  Commodore 64AI · intermediateBASIC

• Format a 16-bit Decimal Number on C64

  A binary score is good for adding points.

  Commodore 64Framework · intermediateAssembly

• Format a Byte as Hexadecimal on C64

  Two hexadecimal digits are a compact way to show a byte in a debugger, password or diagnostic panel.

  Commodore 64Framework · intermediateAssembly

• Fractional Position Updates on C64

  A quarter-pixel step should eventually move the sprite a whole pixel.

  Commodore 64Physics · intermediateAssembly

• Game States and Restart on C64

  Separate title, play, pause and game over, preserve a paused session and reset a new one exactly once.

  Commodore 64Framework · intermediateAssembly

• Gate a Dialogue Choice with Flags on C64

  A dialogue option can depend on what the player knows and change what happens next.

  Commodore 64Framework · intermediateAssembly

• Give a BASIC turn a deadline on C64

  Use a reusable elapsed-clock helper, keep untimed play valid, and let a deadline expire without blocking on input.

  Commodore 64Framework · intermediateBASIC

• Give a turn a KERNAL deadline

  Keep untimed turns useful, then add a serviced jiffy-clock deadline with an explicit input policy.

  Commodore 64Framework · intermediateAssembly

• Give Ready Jobs a Fair Turn in C64 BASIC

  Select one of eight ready slots from a retained rotating start position, wrapping fairly and leaving work execution to the caller.

  Commodore 64Framework · intermediateBASIC

• Group Nearby Objects into Fixed Buckets in C64 BASIC

  Store up to four object IDs in each of four spatial buckets, with explicit capacity overflow and read-only queries.

  Commodore 64Physics · intermediateBASIC

• Hardware Sprites

  Show a complete 24×21 sprite, set its ninth X bit, and preserve the other sprites’ shared registers. Verified on PAL and NTSC emulators.

  Commodore 64Rendering · beginnerAssembly

• Insert a Score and Keep Ties Stable in C64 BASIC

  Maintain four descending byte scores with associated tags, retaining existing equal scores first and rejecting an invalid table without changing it.

  Commodore 64Framework · intermediateBASIC

• Insert into a High-score Table on C64

  A score table needs a clear answer for ties, a full table and the player who just misses the cut.

  Commodore 64Framework · intermediateAssembly

• Interpolate Between Byte Endpoints on C64

  A menu panel or camera can move towards an endpoint without a different hand-written position for every frame.

  Commodore 64Physics · intermediateAssembly

• Joystick Reading

  Read both C64 joystick ports, distinguish holds, presses and releases, and map one event to one action.

  Commodore 64Input · beginnerAssembly

• Jump Buffering and Coyote Time on C64

  Press Jump just before landing and it is frustrating when the press disappears.

  Commodore 64Physics · intermediateAssembly

• Keep a Bounded Cell-edit Undo Log on C64

  Undo should restore the previous cell value, including when the same cell was edited twice.

  Commodore 64Framework · intermediateAssembly

• Keep a Menu Selection Visible on C64

  A list can hold more choices than the screen has rows while its cursor still stays in view.

  Commodore 64Input · intermediateAssembly

• Keep a Small Position History on C64

  A trailing companion needs where the leader was, not another guess at where it might be going.

  Commodore 64Framework · intermediateAssembly

• Keep a Stable Interaction Focus on C64

  A prompt should not flicker between two nearby objects whenever their distances differ by one pixel.

  Commodore 64Framework · intermediateAssembly

• Keep a Stable Priority Event Queue on C64

  An urgent event may need service before an older routine event, while equal priorities should remain fair.

  Commodore 64Framework · intermediateAssembly

• Keep a Turn Until the Route Opens in C64 BASIC

  Retain a requested turn, try it before the current direction and move at most one checked grid cell per service.

  Commodore 64Framework · intermediateBASIC

• Keep an Effect on a Timer in C64 BASIC

  Track a finite duration and pulse interval, including a possible pulse on the final active tick.

  Commodore 64Framework · intermediateBASIC

• Keep Camera Shake Alive Across Updates in C64 BASIC

  Produce bounded signed camera offsets for a retained lifetime, without modifying the world position.

  Commodore 64Rendering · intermediateBASIC

• Keep Camera Shake out of World State on C64

  An impact can shake the view without moving the player, the level or the collision geometry.

  Commodore 64Rendering · intermediateAssembly

• Keep Fractional Tick Credit in C64 BASIC

  Emit a chosen numerator of events per denominator calls without discarding the remainder.

  Commodore 64Framework · intermediateBASIC

• Keep Fractions Between Position Updates in C64 BASIC

  Add a signed eight-point-eight displacement to a retained position, preserving sub-unit motion and making wrapping explicit.

  Commodore 64Physics · intermediateBASIC

• Keep Interaction Focus Stable in C64 BASIC

  Choose an eligible nearby target while retaining the current one within an explicit distance margin.

  Commodore 64Framework · intermediateBASIC

• Keep Object References with Their Lifetimes in C64 BASIC

  Allocate, query and release four stable slots while rejecting references to an earlier generation of a slot.

  Commodore 64Framework · intermediateBASIC

• Keep Starts and Resumes Separate in C64 BASIC

  Separate fresh sessions, held-button edges and pause/resume transitions with explicit caller-owned progress.

  Commodore 64Framework · intermediateBASIC

• Keep the Camera Quiet Until Needed in C64 BASIC

  Retain a world-space camera, move only beyond a screen-relative quiet zone and clamp the result to valid scrolling bounds.

  Commodore 64Physics · intermediateBASIC

• Keep Track of Cells That Need Redrawing in C64 BASIC

  Mark, inspect and consume pending cell updates without losing repeated marks or crossing the two-byte boundary.

  Commodore 64Rendering · intermediateBASIC

• Keep Travel Remaining After a Bounce in C64 BASIC

  Move within inclusive axis bounds while consuming the whole requested distance, retaining direction and counting repeated reflections.

  Commodore 64Physics · intermediateBASIC

• Keep Urgent Events in a Stable Queue in C64 BASIC

  Queue four event/priority pairs, service the highest priority first and preserve insertion order for equal priorities.

  Commodore 64Framework · intermediateBASIC

• Land on a One-way Platform on C64

  A fast-falling character can cross a thin platform between two updates without ever having its feet exactly on the top.

  Commodore 64Physics · intermediateAssembly

• Land While Crossing a One-way Platform in C64 BASIC

  Compare old and proposed feet against a platform top, using widened horizontal spans and a deliberate drop-through flag.

  Commodore 64Physics · intermediateBASIC

• Limit Hits to an Attack Window in C64 BASIC

  Accept each target once during a chosen attack interval, retaining a hit set across updates.

  Commodore 64Framework · intermediateBASIC

• Limit Hits to an Attack Window on C64

  A sword can overlap the same enemy for several frames without dealing damage on every frame.

  Commodore 64Framework · intermediateAssembly

• Look Up a Bounded Byte Dictionary on C64

  An item code, tile identifier or command token often needs a small associated value.

  Commodore 64Framework · intermediateAssembly

• Look Up a Small Slope Surface in C64 BASIC

  Query an eight-column height profile, mirror it without copying data and reject a surface that would exceed the byte coordinate range.

  Commodore 64Physics · intermediateBASIC

• Look Up Tile Properties on C64

  The picture number in a map does not automatically tell you whether a tile is solid, harmful or climbable.

  Commodore 64Rendering · intermediateAssembly

• Manhattan Distance on C64

  On a four-way grid, distance is the horizontal gap plus the vertical gap.

  Commodore 64Framework · intermediateAssembly

• Menu Key Repeat on C64

  A menu should move once when you press Down, pause briefly, then scroll while you hold it.

  Commodore 64Framework · intermediateAssembly

• Mirror an Eight-bit Bitmap Row on C64

  A stored row of pixels can face the other way without keeping a second copy of the artwork.

  Commodore 64Rendering · intermediateAssembly

• Move, collect and respond on the Commodore 64

  Combine input, bounded movement, box collision, drawing and sound in a small program you can take apart.

  Commodore 64Framework · beginnerAssembly

• Multiply Two Bytes into a Word on C64

  A small machine still needs products larger than one byte: an area, a score multiplier or a scaled distance.

  Commodore 64Framework · intermediateAssembly

• Offer Dialogue Choices with Quest Flags in C64 BASIC

  Test quest conditions before accepting a choice, then apply its changes once.

  Commodore 64Framework · intermediateBASIC

• Pack Live Objects and Keep Their Order in C64 BASIC

  Compact paired flag/payload arrays in place, clearing vacated entries while preserving unused capacity.

  Commodore 64Framework · intermediateBASIC

• Parse a Bounded Decimal Number on C64

  A score name box and a numeric prompt need different input rules.

  Commodore 64Framework · intermediateAssembly

• Parse Two Hexadecimal Digits on C64

  A short hexadecimal input still needs validation before it becomes an address, colour or seed.

  Commodore 64Framework · intermediateAssembly

• Parse Two-Word Commands on C64

  Reusable BASIC V2 code turns words into game concepts, with exact matching, synonyms, clear errors and measured costs.

  Commodore 64Input · intermediateBASIC

• Patrol Between Two Endpoints on C64

  A guard walks to the end of a corridor, turns and comes back.

  Commodore 64Framework · intermediateAssembly

• Pick the Nearest Active Target in C64 BASIC

  Choose among four active candidates using Manhattan distance, preserving the first slot on ties and retaining the ninth distance bit.

  Commodore 64AI · intermediateBASIC

• Print a Bounded Text Region in Commodore 64 BASIC

  Print a map slice with a complete bounds and tile-ID preflight before any output.

  Commodore 64Rendering · beginnerBASIC

• Project a World Point into the View in C64 BASIC

  Convert byte-pair world coordinates to visible screen positions without dropping high bytes or wrapping negative differences.

  Commodore 64Rendering · intermediateBASIC

• Project World Points into a Viewport on C64

  A world can be larger than the screen even when the drawing routine expects byte-sized screen coordinates.

  Commodore 64Rendering · intermediateAssembly

• Propose a Push from a Moving Solid in C64 BASIC

  Detect a one-dimensional moving solid crossing an actor and propose a safe displacement or an explicit blocked result.

  Commodore 64Physics · intermediateBASIC

• Push a Block Atomically on C64

  A crate should move with the player only when the space beyond it is free.

  Commodore 64Framework · intermediateAssembly

• Push a Crate After Checking the Whole Move in C64 BASIC

  Check the adjacent cell and the space beyond a crate before changing the player or map.

  Commodore 64Framework · intermediateBASIC

• Push an Actor with a Moving Solid on C64

  A moving wall should carry an actor ahead of its leading face, or report that the actor cannot fit.

  Commodore 64Physics · intermediateAssembly

• Query a Byte Map on Commodore 64

  Read and change map cells, look up tile properties and convert world positions with reusable 6502 code and an explicit memory contract.

  Commodore 64Rendering · intermediateAssembly

• Query a Small Slope Height Profile on C64

  A sloping tile needs a surface at each horizontal position, not one flat collision edge.

  Commodore 64Physics · intermediateAssembly

• Query a Thin Grid Sight Line in C64 BASIC

  Visit the cells along an integer line and stop at the first blocking cell.

  Commodore 64AI · intermediateBASIC

• Query and Change a Tile Map in Commodore 64 BASIC

  Keep room data separate from its picture, with checked reads, edits, properties and world-to-cell conversion.

  Commodore 64Rendering · beginnerBASIC

• Quest and Inventory Flags on C64

  A key collected, a door unlocked, a conversation finished: eight yes/no facts fit in one byte.

  Commodore 64Framework · intermediateAssembly

• Queue Game Events in C64 BASIC

  Store byte-valued game requests in a bounded FIFO, with explicit full/empty results and validated wrap-around.

  Commodore 64Framework · intermediateBASIC

• Raster Splits

  Fire an interrupt when the beam reaches a chosen scanline and change a VIC-II register mid-screen — the basis of colour bars, split panels, and beating the chip's limits.

  Commodore 64Rendering · intermediateAssembly

• Read and Edit Packed Four-bit Cells in C64 BASIC

  Store two logical cells per numeric byte value and update either half without damaging its neighbour.

  Commodore 64Rendering · intermediateBASIC

• Read and Update Packed Four-bit Cells on C64

  Sixteen tile values do not need sixteen whole bytes when each value fits in four bits.

  Commodore 64Rendering · intermediateAssembly

• Read and Write Hexadecimal Bytes in C64 BASIC

  Format one byte as two ASCII digits and parse two checked digits back into a byte.

  Commodore 64Framework · intermediateBASIC

• Read Bits from a Bounded Data Block on C64

  Packed flags and small fields can share a byte, provided the reader knows exactly how many bits remain.

  Commodore 64Framework · intermediateAssembly

• Read Bits from a Small Data Block in C64 BASIC

  Extract up to eight bits at a time from a four-byte block, keeping a cursor and rejecting a field that would cross the end.

  Commodore 64Framework · intermediateBASIC

• Read Decimal Digits with Bounds in C64 BASIC

  Accept one ASCII digit at a time while retaining the valid prefix, rejecting other characters and refusing values above 255.

  Commodore 64Framework · intermediateBASIC

• Rebuild Byte Values from Deltas in C64 BASIC

  Expand up to eight signed byte differences from an explicit base, wrapping modulo 256 and preserving output when input is invalid.

  Commodore 64Framework · intermediateBASIC

• Recognise a Short Input Sequence on C64

  A sequence is about order.

  Commodore 64Input · intermediateAssembly

• Recognise an Overlapping Input Sequence in C64 BASIC

  Remember a short ordered prefix, pulse on a match and retain the useful suffix for overlapping matches.

  Commodore 64Input · intermediateBASIC

• Rectangle Overlap

  Check two boxes without wrapped coordinates, distinguish touching from overlap, and reuse the existing C64 helper.

  Commodore 64Physics · beginnerAssembly

• Reflect a Surface-normal Speed with Restitution on C64

  A bounce can lose speed along a wall’s normal while keeping its sideways motion.

  Commodore 64Physics · intermediateAssembly

• Reflect Movement at Axis Bounds on C64

  A fast ball should use the distance left after a bounce rather than sticking to the wall.

  Commodore 64Physics · intermediateAssembly

• Reflect Speed with a Material Coefficient in C64 BASIC

  Scale a normal-speed magnitude by quarter-step restitution, reverse its direction and preserve its tangential component.

  Commodore 64Physics · intermediateBASIC

• Reject Stale Object Handles on C64

  A reused pool slot should not let an old reference suddenly name a different enemy.

  Commodore 64Framework · intermediateAssembly

• Remember an Unordered Contact Pair in C64 BASIC

  Remember which pairs have already been considered during one traversal, without treating reversed IDs as a new pair.

  Commodore 64Physics · intermediateBASIC

• Remember Contact Pairs for a Step on C64

  The same contact can appear in both objects’ candidate lists.

  Commodore 64Physics · intermediateAssembly

• Remember Jump Presses for a Short Window in C64 BASIC

  Retain separate jump-buffer and coyote timers, grant a jump only when they overlap and consume permission after the pulse.

  Commodore 64Physics · intermediateBASIC

• Remember Previous Positions in a Ring in C64 BASIC

  Append positions without shifting the buffer, then query a sample by its age, including after wraparound.

  Commodore 64Framework · intermediateBASIC

• Remember Which Cells Need Redrawing on C64

  Changing one cell should not force a whole board to be redrawn.

  Commodore 64Rendering · intermediateAssembly

• Repeat a Held Menu Control in C64 BASIC

  Pulse on a new hold, wait a configurable delay, then repeat at a separate cadence until release.

  Commodore 64Framework · intermediateBASIC

• Repeat a Small Random Sequence in C64 BASIC

  Seed and restore a portable eight-bit LFSR, expose corrupted zero state and keep random-call order explicit.

  Commodore 64Framework · intermediateBASIC

• Report Trigger Enter, Stay and Exit Events on C64

  Standing in a doorway should not count as entering it on every update.

  Commodore 64Framework · intermediateAssembly

• Report Trigger Entry, Stay and Exit in C64 BASIC

  Turn an eight-bit overlap snapshot into separate entered, stayed and exited masks while retaining the previous snapshot.

  Commodore 64Framework · intermediateBASIC

• Resolve Held Input to Four Directions in C64 BASIC

  Cancel opposed directions, then use retained axis preference to choose a single direction from a diagonal.

  Commodore 64Input · intermediateBASIC

• Resolve Input to Four Directions on C64

  A maze character needs one direction even when the player holds a diagonal.

  Commodore 64Input · intermediateAssembly

• Resource Counters on C64

  An empty magazine should refuse a shot, not turn into 255 rounds.

  Commodore 64Framework · intermediateAssembly

• Retain Climbing State on a Ladder in C64 BASIC

  Enter, retain and leave a bounded ladder mode with explicit gravity and jump-release outputs.

  Commodore 64Physics · intermediateBASIC

• Reusable Object Slots on C64

  Give bullets, enemies and effects fixed slots, handle a full pool, and remove objects without skipping their neighbours.

  Commodore 64Framework · intermediateAssembly

• Reuse Object Slots in C64 BASIC

  Allocate, release and age reusable object slots, with explicit full-pool results and caller-owned payloads.

  Commodore 64Framework · intermediateBASIC

• Reveal Counted Text Over Time on C64

  A line of dialogue can appear a character at a time, with a button to show the rest immediately.

  Commodore 64Rendering · intermediateAssembly

• Run a Timed Wave of Events in C64 BASIC

  Emit up to four event IDs with explicit quiet-call delays, retaining the cursor and emitting at most one event per call.

  Commodore 64Framework · intermediateBASIC

• Save and Restore a Small Game State in C64 BASIC

  Capture three byte-valued fields in RAM and validate the complete stored record before restoring any live field.

  Commodore 64Framework · intermediateBASIC

• Seeded Random Numbers on C64

  Reusable seed and next routines, repeatable draws, state replay and a visible zero-state trap.

  Commodore 64Framework · intermediateAssembly

• Select Ready Work with Round-robin Fairness on C64

  Background jobs should each get a turn when the game can afford only one piece of work this tick.

  Commodore 64Framework · intermediateAssembly

• Select the Nearest Active Target on C64

  An enemy or homing projectile needs a target-selection rule that stays predictable when candidates tie.

  Commodore 64AI · intermediateAssembly

• Sequence Counted Notes and Rests on C64

  A short tune needs a clock and a sequence of notes, not a fresh sound effect every frame.

  Commodore 64Audio · intermediateAssembly

• Service a Logical Attack–Decay–Sustain–Release Envelope on C64

  A sound can swell, settle and fade instead of switching between full volume and silence.

  Commodore 64Audio · intermediateAssembly

• Service a Small Spawn Timeline on C64

  A wave can have deliberate pauses without burying every spawn in the main loop.

  Commodore 64Framework · intermediateAssembly

• Service a Timed Status Effect on C64

  A poison effect needs a duration and a pulse interval, not a fresh timer every time the actor is updated.

  Commodore 64Framework · intermediateAssembly

• Service an Action Cooldown in C64 BASIC

  Keep time moving between requests, then grant an action only when the cooldown and caller-supplied availability allow it.

  Commodore 64Framework · intermediateBASIC

• Shape a Logical Sound Envelope in C64 BASIC

  Service attack, decay, sustain and release as bounded logical control levels with retained gate-edge history.

  Commodore 64Audio · intermediateBASIC

• SID Multi-Voice

  Step a note pattern once per raster interrupt, handing each of the SID's three voices its note from a frequency table — the skeleton of every C64 music player.

  Commodore 64Audio · advancedAssembly

• SID Note Trigger

  Start a note on one SID voice by setting its gate, and end it by clearing the gate, with the envelope rates the chip actually uses.

  Commodore 64Audio · beginnerAssembly

• SID Voice Setup

  Configure a SID voice with frequency, waveform, and ADSR envelope. Foundation for all SID audio programming.

  Commodore 64Audio · beginnerAssembly

• Smooth Scrolling

  Combine VIC-II fine offsets with a complete character and colour shift. Prepare the next column and budget the costly coarse step.

  Commodore 64Rendering · intermediateAssembly

• Sort a Small Draw Order Stably on C64

  When two sprites have the same depth, their order should not flicker from frame to frame.

  Commodore 64Rendering · intermediateAssembly

• Spend and Refill a Resource in C64 BASIC

  Reject unaffordable spending atomically, but accept a refill and cap it deliberately at 255.

  Commodore 64Framework · intermediateBASIC

• Sprite Movement with Bounds

  Move a C64 sprite with joystick port 2, clamp it to the screen edges, and handle its ninth X bit without disturbing other sprites.

  Commodore 64Physics · beginnerAssembly

• Sprite Multiplexing

  Draw sixteen sprites in two fixed bands, with a complete raster IRQ example verified on PAL and NTSC emulators.

  Commodore 64Rendering · advancedAssembly

• Step Each Packed Colour Channel in C64 BASIC

  Unpack logical RGB332, move each channel by one towards its target and repack without cross-channel carry.

  Commodore 64Rendering · intermediateBASIC

• Step Towards a Packed Colour on C64

  A fade can approach its target one channel step at a time instead of treating a packed colour as a single number.

  Commodore 64Rendering · intermediateAssembly

• Stop Fast Motion at a Wall Face in C64 BASIC

  Sweep one interval towards a requested endpoint, returning first contact instead of letting a fast step pass through a wall.

  Commodore 64Physics · intermediateBASIC

• Sweep an Interval Along One Axis on C64

  A fast object can cross a wall between frames even when neither endpoint overlaps it.

  Commodore 64Physics · intermediateAssembly

• Test a Point Against a Circle in C64 BASIC

  Check an inclusive circular boundary without a square root, preserving full coordinate differences and enough arithmetic range for squared distances.

  Commodore 64Physics · intermediateBASIC

• Test a Point Against a Circle on C64

  A round pickup should not become a square just because a box test was convenient.

  Commodore 64Physics · intermediateAssembly

• Test Opaque Pixels in Two Small Masks in C64 BASIC

  Align two eight-by-eight opaque masks, then return the first overlapping row rather than treating overlapping boxes as a pixel hit.

  Commodore 64Physics · intermediateBASIC

• Test Sight Along a Grid Row or Column on C64

  A sentry looking down a corridor must stop at the first wall.

  Commodore 64AI · intermediateAssembly

• Test Two Small Opaque Pixel Masks on C64

  Two sprite boxes can overlap while their visible shapes still miss each other.

  Commodore 64Physics · intermediateAssembly

• Trace a Thin Grid Line of Sight on C64

  A guard looking across a room needs more than a same-row check.

  Commodore 64AI · intermediateAssembly

• Transfer Inventory Stacks Atomically on C64

  Moving arrows from a chest to a pack should never remove more than the pack can hold.

  Commodore 64Framework · intermediateAssembly

• Transpose an Eight-by-eight Bitmap on C64

  Turning rows into columns is the building block behind rotating small glyphs and adapting bitmap layouts.

  Commodore 64Rendering · intermediateAssembly

• Turn a Score into Five Digits in C64 BASIC

  Convert an unsigned 16-bit value into exactly five ASCII character codes, preserving its two input bytes and making leading-zero policy explicit.

  Commodore 64Framework · intermediateBASIC

• Turn an Analogue Axis into Intent on C64

  A joystick that rests a little off-centre should not make the player creep across the screen.

  Commodore 64Input · intermediateAssembly

• Undo Edits to a Small Board in C64 BASIC

  Record each cell’s previous value before editing it, then restore edits in reverse order with a four-entry log.

  Commodore 64Framework · intermediateBASIC

• Validate a Save Before Replacing Live State on C64

  A damaged save should leave the current game alone rather than half-replacing it with invalid state.

  Commodore 64Framework · intermediateAssembly

• Wait for a command on C64 in BASIC

  Keep an untimed game waiting for the player, with a reusable command update, a working variation and a diagnosed state-reset mistake.

  Commodore 64Framework · beginnerBASIC

• Walk an Ordered Waypoint Route on C64

  A guard should reach a waypoint before choosing the next, even when one movement step would overshoot it.

  Commodore 64AI · intermediateAssembly

• Wrap and Skip Menu Options in C64 BASIC

  Move a bounded selection in either direction, wrap at the ends and skip options that are currently disabled.

  Commodore 64Input · intermediateBASIC

• Wrap and Skip Menu Options on C64

  A menu should wrap cleanly at either end and skip options the player cannot choose.

  Commodore 64Input · intermediateAssembly

• Write Bits into a Small Data Block in C64 BASIC

  Pack the low bits of a value into a four-byte block while preserving neighbouring bits and rejecting incomplete writes.

  Commodore 64Framework · intermediateBASIC

• Write Packed Bits with Bounds on C64

  Flags and short fields can share a compact record without overwriting their neighbours.

  Commodore 64Framework · intermediateAssembly