MSXnano v1.2 — goauld standalone core + authentic MSX speed

MSXnano v1.2

Rebuilt on the goauld standalone core (cleaner base) keeping the standalone / USB / WiFi design.

Highlights

• ⏱️ Authentic MSX speed: added the per-M1 opcode-fetch wait-state a real MSX board provides. CPU now runs at ~100% (measured 101% / 3.59 MHz) instead of ~116%. Toggleable via define ENABLE_M1_WAIT.
• 📶 WiFi BIOS integrated: the ESP8266 UNAPI ROM now ships inside the single BIOS pack flashed at 0x200000 — no separate WiFi ROM step.
• 🔌 WiFi UART pins aligned with the wiring diagram (rx → pin 77, tx → pin 73).
• ⌨️🕹️ USB keyboard + joystick via onboard BL616 (FPGA Companion), discrete LEDs, HDMI, SD/Nextor 2.1.

Flashing (3 steps)

1. msxnano.fs → FPGA flash at 0x000000 (Gowin Programmer).
2. BL616 FPGA Companion firmware (see README).
3. BIOS pack goauld_rom_int.bin → 0x200000 (includes BIOS + Nextor + WiFi ROM + config). Build locally — copyright, not distributed.

Assets

• msxnano.fs — FPGA bitstream (Tang Nano 20K, GW2AR-18).

Code review and engineering improvements (standalone bus removal, USB/LED integration, authentic M1 wait-state) by Claude (Anthropic).