Hardware

The physical build: bill of materials, assembly plan, mechanical layout, electrical paths, component sourcing.

System-level

canonical-spec.md — the Canonical Hardware Specification: the single source of truth for every hardware value.
build-specification.md — top-level BOM, assembly plan, hardware topology, dev-vs-prod-mode.
wiring-diagram.md — block-level system wiring (power, data, audio, input) as a Mermaid diagram.
sourcing-guide.md — component sourcing notes, candidate part families, vendor links, supplier risk.
shopping-list.xlsx — the buy list (binary; opaque to the audit).

One page per major hardware subsystem. Each page consolidates the relevant ADRs + the BOM rows + the bring-up steps for that subsystem.

processor.md — Raspberry Pi Zero 2 W (primary processor: Linux, nOSh, HDMI, USB hub host).
coprocessor.md — Raspberry Pi Pico 2 (RP2350) realtime I/O coprocessor (audio + auxiliary OLED).
primary-display.md — Elecrow 7” IPS, 1024×600, 80×25 grid, 12×24 cell, amber monochrome.
auxiliary-display.md — CIPHER-LINE OLED; see the parent canonical spec for hardware values and the GWP-619 bench note for the temporary 8080 harness.
keyboard.md — custom mechanical 31-key (TERM included) build, Kailh Choc v1 hot-swap, MBK keycaps, QMK.
audio.md — YM2149 PSG → I2S → WM8960 codec → Gikfun 2″ speaker / 3.5 mm stereo headphone jack.
cartridge-interface.md — SD card in custom clamshell sled, USB-MSC bridge IC.
power.md — Waveshare UPS Module 3S (3× 18650) → 5 V/5 A rail (whole device incl. display), 12.6 V barrel-jack charge, INA219 battery monitor (ADR-0038); runtime envelope.
enclosure.md — Pelican 1170 + 3D-printed inset panels (Pelican shell unmodified).