Attribute Raid

Attribute Raid is a River Raid-style prototype with a ZX Spectrum 48K-compatible renderer and optional AY-3-8912 sound for the Spectrum 128K or a 48K machine with an AY interface. All code executed on the Spectrum is well-commented Z80 assembly; there is no C runtime. A dedicated build uses the Timex TC2048/TC2068/ TS2068 graphics modes: its 8×1 hi-colour screen gives every scanline its own colour pair instead of the Spectrum's 8×8 attribute cells.

The sound effects, the sprites, and the sprite colours are unapologetically "stolen" from the Atari 2600 original: they were transcribed from Thomas Jentzsch's commented disassembly of River Raid (Activision, 1982), archived at https://web.archive.org/web/20230404092047/http://www.bjars.com/source/RiverRaid.asm (originally bjars.com/source/RiverRaid.asm). Only derived register values and shapes are reproduced here, no original code.

▶ Play the latest build in your browser — every push deploys the current Spectrum 128K TAP to GitHub Pages, where it runs in the embedded JSSpeccy 3 emulator with AY sound. (The Timex hi-colour build is not playable there; use the releases.)

The loading screen above (assets/loading-screen.png) ships in both TAPs as a SCREEN$ block, converted to the Spectrum's 6912-byte format in assets/loading-screen.scr and displayed while the code block loads.

Status: 0.3.0 is a beta release. The core gameplay is playable, but level progression and final balancing are not complete yet: aircraft controls, two speed modifiers, firing, collisions, two lives, fuel and refuelling, a crash animation, scoring, AY sound, and a GAME OVER screen are in place.

Building and running

make              # build both TAPs, no external Z80 toolchain required
make run          # ZEsarUX as a Spectrum 128K with AY sound
make run-timex    # ZEsarUX as a TC2068: 8x1 hi-colour plus native AY

The default build produces two files:

• build/attribute-raid.tap for the ZX Spectrum 48K/128K,
• build/attribute-raid-timex.tap for the Timex TC2048/TC2068/TS2068 hi-colour mode.

All remaining targets (profiling builds, per-model emulator runs, joystick configuration) are described in docs/building.md.

Controls

• O / P — move the player aircraft left / right at 2 px per frame,
• no speed key — base scrolling speed of 1 px per frame,
• hold Q — fast scrolling: a flat 2 px per frame in every scene,
• hold A — temporarily reduce scrolling to an average of 0.5 px per frame,
• SPACE — fire,
• R — start a new game with two lives, a zero score, and a new course.

The Kempston joystick supports left/right, FIRE, and temporary speed changes. Up is equivalent to Q, and down is equivalent to A. After loading, the game waits at a small start screen until SPACE or Kempston FIRE is pressed. After the second life is lost, release FIRE before pressing it again to start a new game; this prevents the GAME OVER screen from being skipped accidentally.

Documentation

• docs/building.md — every make target, the emulator configuration, the built-in assembler/toolchain, and the module layout.
• docs/timex.md — the Timex 8×1 hi-colour mode and the TC2048/TC2068/TS2068 AY hardware handling, including the optional-AY probe.
• docs/renderer.md — the V3 course model, the incremental renderer, colour/bridge/sprite handling, and the performance budget.
• docs/gameplay.md — collision rules, HUD, fuel, tanks, bridges, and scoring details.
• docs/sound.md — the Atari-derived AY effects and the TIA-to-AY conversion pipeline.
• CHANGELOG.md — release history.