AC Native OS — Common Lisp Edition Progress (2026.03.23) #

Overview #

A bare-metal Common Lisp OS runtime for AC Native, using SBCL + CFFI. Boots directly to notepat (musical keyboard instrument) on real ThinkPad hardware via UEFI.

Architecture #

• Runtime: SBCL 2.6.2 compiled to standalone binary (~12MB)
• Graphics: DRM/KMS framebuffer with pixel scaling (targets ~200px wide)
• Audio: ALSA PCM with 32-voice polyphonic synth (48kHz stereo S16LE)
• Input: evdev keyboard polling (full QWERTY)
• Build: Docker reproducible build (Fedora 43 + GCC 15 + Linux 6.19.9)
• Boot: UEFI → Linux kernel with embedded initramfs → SBCL binary as /init child

What Works (2026-03-22) #

Core Runtime #

• DRM display init (card0/card1/card2 probe + fbdev fallback)
• Double-buffered dumb buffers with page flip
• Pixel scaling with optimized memcpy-based fb-copy-scaled
• 60fps frame sync via clock_nanosleep
• evdev input polling (keyboard)
• ALSA audio output with mixer unmute + volume max
• 5 oscillator types: sine, square, triangle, sawtooth, noise
• Polyphonic synth (32 voices, per-voice pan/attack/decay/duration)
• Audio thread with lock-based voice management

Graphics #

• Immediate-mode primitives: wipe, ink, plot, line, box, circle
• Alpha blending (per-pixel ARGB32)
• 6x10 bitmap font rendering with scaling
• Color system (make-color, pack-argb32, blend)

Notepat Instrument #

• QWERTY keyboard → chromatic note mapping (2.5 octaves per layout)
• Key down → synth voice, key up → kill voice
• Per-note chromatic rainbow colors
• Background color lerps to average of active notes
• Trail effect: fading colored bars per note+octave on release
• Active note indicators (bright full-width bars)
• Octave control (1-9 keys, arrow up/down)
• Wave type cycling (Tab: sine → triangle → sawtooth → square → noise)
• Confirmation blip sound on wave switch
• Stereo panning (lower notes left, higher notes right)
• Status bar: wave type, octave, FPS counter
• ESC triple-press to quit
• Power button to quit
• Quick mode (Shift toggles short attack for staccato)
• Metronome (Space toggle, -/= BPM, clock-synced, pendulum visual)
• Arrow left/right wave switching
• Kill voices on octave/wave change (prevents orphaned notes)
• Wave type selector bar (bottom of screen)
• Swank REPL server (port 4005, auto-start)
• IP address display on screen
• WiFi auto-connect from init (reads saved creds from USB)
• ac-os scan and ac-os repl commands for remote development

Build System #

• Docker reproducible build (Dockerfile.builder)
• AC_BUILD_LISP=1 flag swaps CL binary into initramfs
• Oven OTA pipeline compatible
• USB flash via privileged Docker container

What's Next #

Short Term #

• Audio: mixer unmute verification (silent on some boots)
• Audio: sample recording/playback (microphone capture + sample bank)
• Audio: echo/room effect
• Audio: pitch shift (trackpad or slider)
• Input: touch/trackpad support
• Display: boot animation / splash screen
• System: USB log writing for debug
• System: config.json reading (handle, credentials)

Medium Term #

• WiFi management (wpa_supplicant integration)
• OTA self-update
• Metronome (clock-synced)
• Text-to-speech (flite integration)
• Multiple pieces with piece switching (prompt → notepat)
• Touch grid UI for note pads

Long Term #

• KidLisp evaluator in CL (replace QuickJS)
• Network/WebSocket for multiplayer
• Full piece API surface (matching JS disk.mjs)

File Map #

Hardware Tested #

• ThinkPad X1 Nano Gen 2 (Intel i915)
• ThinkPad Yoga 11e Gen 5 (Intel i915)