Trinity
Alternative firmware for the Neo6502: it builds on Paul Robson's official firmware and adds NeoDOS, a USB modem, new video modes and over 100 API functions. Article → · Source code →
In development · 0.16.99
Tachibana project · 65C02 platform
Neo6502
W65C02S + RP2040 — Olimex
A real 65C02 at 6.25 MHz, an RP2040 as chipset, HDMI out, a USB keyboard — for 30 euros. We make it a test bench and a target for our 6502 ports.
Phosphoneo (cycle-stepped reference model), keyboard driver, BBC Micro compatibility layer, Trinity, our firmware (NeoDOS, USB modem, video modes), AsteroNeo (Astéroric ported), Prophet (program repository, live), Oric 2 Neo, Yuzu and Sudachi (two game ports). Everything is checked on emulators, then on a real board.
Neo6502
The Neo6502 at a glance
| Processor | W65C02S |
| Microcontroller | RP2040, 2 MB flash |
| Video | DVI/HDMI — 320×240, 256 |
| Keyboard | USB-A host |
| Expansion | UEXT, 6502 bus |
| Audio | 3.5 mm, speaker |
| Form factor, licence | 80 × 55 mm, OSHW |
| Price | 30 € |
320×240 video in 256 colours, 6.25 MHz and ≈ 61K of usable RAM: figures from our repositories' documents; the rest comes from the Olimex product sheet.
Firmware
Trinity, our firmware
Software
Programs for the Neo6502
NeoDOS
NeoDOS is Trinity's command shell: an MS-DOS style A:\> prompt to manage your files and run your programs from a USB stick.
In development · v0.32.1
AsteroNeo
Astéroric ported to the Neo6502 (cc65): arcade logic kept as is, API XOR lines, smoothed polygonal asteroids drawn by the RP2040, remappable HID keyboard, 4-channel sound, 30 Hz. .neo binary published. Article → · Source code →
Available · v0.2.0 · 16 September 2026
Prophet
Program repository server compatible with prophet.neo, rewritten in Go security first: HTTP + HTTPS, .neo verification, audit of 56 programs in Phosphoneo, web interface. Live at prophet.3617.fr (AsteroNeo published). Online → · Article →
Available · 0.25.0 · 3 October 2026
Tools
To develop, test, connect
Phosphoneo
Reference emulator of the Neo6502, to test programs without the board: cycle-stepped, 65C02 core validated on 2.54 million test cases, API linked to the firmware code, running without a display, captures, save states. Article → · Wiki →
In development · v0.5.0
Neo6502kbd
Keyboard driver in 65C02 assembly (ca65): events (scancode, modifiers), base / Shift / AltGr / Ctrl mapping compiled from a .kmap (us, fr) by neokbd, a Go tool with a simulator.
In development
Neo6502bbc
BBC Micro MOS layer → Neo6502 API (OSWRCH, OSBYTE, OSWORD, OSCLI…). The reload BBC emulator boots MOS 1.20, BASIC 2, DFS, and starts Spellbinder.
In development
Neo6502 Wi-Fi modem
C firmware that turns a Raspberry Pi Pico W into a Wi-Fi modem for the Neo6502: ESP8266 AT dialect (prophet.neo and neo-networking work unmodified), Hayes modem, USB CDC and UART on UEXT, TLS terminated in the Pico W with a verified certificate. Validated on the board. Source code →
Available · v0.3.1 · 24 September 2026
SWD debugging
A Pico W flashed with debugprobe, three wires (GP2, GP3, GND) and OpenOCD: read the running RP2040's memory, even with a stuck firmware. Its wireless sequel, over Wi-Fi: the Eliott65Sonde wiki.
Planned
Exploratory work
This work is exploratory: no date, no commitment.
Eliott65
A firmware, kernel and system written from scratch for the Neo6502kbd: the kernel lives in the RP2040, and the 6502 keeps 65,528 bytes out of 65,536. An experiment, told in its wiki.
In development · v0.129.0
Oric 2 Neo
A next-generation Oric on the Neo6502: Oric-1/Atmos compatible (ULA, VIA, AY emulated), extended by ROM and firmware.
Planned
Yuzu
Port to the Neo6502 of a strategy game written in 6502 assembly (bit-exact on Oric): blitted mono framebuffer, file-based overlays, AI ~6× faster.
Planned
Sudachi
Port to the Neo6502 of an adventure game, through a script interpreter (llvm-mos): Neo6502 platform layer, engine shared with the Oric version.
Planned
Transparency
On the board
A Neo6502 board is now on the desk: our programs published on prophet.3617.fr — the Trinity firmware, NeoDOS, ProphetGui, AsteroNeo, Poker and the others — have all been tested on it. The automated tests keep running in the official emulator, in Phosphoneo and in co-simulation (libemul).
Articles
Going further
Neo6502 Chess 0.1: chess in assembly, online
Our chess program for the Neo6502 is out in beta on Prophet. Written in 6502 assembly, it plays against you, against itself, or puts you in front of another board over the Internet. Read the article →
By bmarty · Tachibana · 10 November 2026
Le Manoir du Dr Genius returns, in isometric view
Loriciels' 1984 Oric adventure is reborn on the Neo6502 as an isometric point-and-click game, played with the mouse. A public beta is on Prophet. Read the article →
By bmarty · Tachibana · 10 November 2026
Using Phosphoneo: play, test, script and debug on the Neo6502
What Phosphoneo is for, in practice: playing, trying a program in one line, scripting and filming a play-through, debugging, resuming a run, testing — and what it does not measure yet. Read the article →
By bmarty · Tachibana · 30 October 2026
Prophet 0.25: play in the browser, and the Oric
Seventeen days after going online, our Prophet server moves from 0.6 to 0.25. Programs start in the browser, the Oric joins the Neo6502, and each program page says what the program needs to work. Read the article →
By bmarty · Tachibana · 3 October 2026
Debugging the Neo6502 over SWD: a Pico W as a probe
When the screen stays black and the serial port is silent, the RP2040's debug port is still there. A Pico W, three wires and OpenOCD: you read the board's memory while it runs, and even type at its keyboard for it. Read the article →
By bmarty · Tachibana · 26 September 2026
A DIR that switches off the screen: hunting a shared lock
In Hercules mode, the first DIR command switched the screen off. Twelve fixes, eleven refuted by measurement — and at the end, an SDK lock shared between the two cores, delaying the video interrupt by a single scanline. Read the article →
By bmarty · Tachibana · 25 September 2026
Building a Prophet server for the Neo6502
Prophet is the Neo6502 community's program repository: a client on the board, a server somewhere. We rewrote the server in Go, security first, and put prophet.3617.fr online — with our own programs in it. Read the article →
By bmarty · Tachibana · 16 September 2026
Porting: from Astéroric to AsteroNeo
Same game, same C, another machine: what changes when you move from a 1 MHz 6502 and a home-made bitmap to a 6.25 MHz 65C02 whose RP2040 draws the lines. Read the article →
By bmarty · Tachibana · 16 September 2026
Neo6502: a real 65C02 and an RP2040 for 30 euros — our work in progress
The Olimex board, why Tachibana cares, nine projects under way — now tested on a real board. Read the article →
By bmarty · Tachibana · 15 September 2026 · updated 16 September 2026