.tap
Oric cassettes — fast load, or signal-level playback (--tape-signal) for protected loaders.
Supported
A Tachibana project · Oric emulator
Phosphoric
ORIC-1 / Atmos — cycle-stepped
A cycle-stepped Oric emulator for Linux, macOS and Windows (and the browser), written in C11: a master clock advances the whole machine one cycle at a time, and the 6502 core is cycle-exact — 100 % correct bus sequence over the 2,440,000 cases of the 65x02 oracle.
It runs both natively (SDL2) and in the browser (WebAssembly), with no external dependency. Period peripherals, a built-in debugger, conversion and control tooling. EUPL 1.2-licensed.
Fact sheet
Status Available · v2.1.1 · 30 September 2026
Download phosphoric-2.1.1-linux-x86_64.tar.gz (785 KB)Download phosphoric-2.1.1-windows-x86_64.zip (1.7 MB)Phosphoric source code
Licence: EUPL-1.2 · A problem? Report it on the repository → · Contribute →
Features
What Phosphoric does
Cycle-stepped core
Micro-sequenced 6502 core (100 % against the SingleStepTests/65x02 oracle, NMOS dummy accesses included, interrupts sampled on the penultimate cycle), VIA 6522 clocked per cycle (N+2 period), ULA fetching one cell per cycle (raster splits), AY-3-8910 PSG at clock/8. What the claim covers — and what it does not — is spelled out component by component in docs/ACCURACY.md. Article: Phosphoric 2.0, the cycle-stepped machine →
Period peripherals
Microdisc WD1793 (real mechanical timing, Sedoric boot), Jasmin WD177x controller (TDOS boot, bad-sector injection), TAP cassette down to the signal level, ACIA 6551, the Digitelec DTL 2000 card (V23 Minitel), Mageco / ORICON MIDI, IJK joystick, Centronics printer and MCP-40 plotter.
LOCI & telematics
LOCI interface (FAT SD storage, USB HID), the PicoWiFiModemUSB WiFi modem, and the V23 / Digitelec modem to replay early telematics and bridge to the Minitel / Videotex heritage (the PAVI project).
Built-in debugger
Conditional and raster breakpoints, watchpoints, undo (rewind), a symbol-aware disassembler, an inline assembler, an ncurses TUI — and a remote GDB stub to debug the 6502 from gdb / VS Code.
Control & integration
--control mode (a text protocol for the OricForge IDE), a REST HTTP API, deterministic input record / replay (“TAS movie”), AVI video export, screenshots and Chromecast / Google Cast streaming.
Native, browser & free
An SDL2 build on Linux, Windows and macOS, or WebAssembly in the browser — byte-for-byte identical output. On-screen keyboard, CRT filter, .ost save states. Released under the EUPL 1.2 license.
See the full feature list → · Technical documentation → · Articles →
Media
Supported formats
.dsk
Microdisc / Sedoric floppies, with realistic WD1793 mechanical timing.
Supported
.rom 16K
Machine ROMs bootable at $C000: BASIC 1.0 / 1.1, FOCAL, COMAL, FR / DE / ES variants…
Bootable
.ost
Save states with a CRC32 integrity check — F2 / F4 to save and reload on the fly.
Supported
Download & build
Get it and build it
Source code
The repository is public under the EUPL 1.2 license. Clone it, open an issue, send a patch.
Codeberg · Framagit · GitHubBuild natively
On Debian / Ubuntu, with SDL2:
sudo apt install build-essential libsdl2-dev
make SDL2=1
# then ./oric1-emu -r roms/basic11b.rom
Browser build
Compiled to WebAssembly (make wasm) and already online: it also powers the “Run online” button on the catalogue entries.
Roadmap
Where development stands
Phosphoric is available (version 2.1.1, 30 September 2026) and remains under active development, backed by a suite of 1,208 automated tests in 60 suites (100 % green, Linux / Windows / macOS CI). Indicative status below — the repository is authoritative.
V2 — cycle-stepped machine
Master clock, cycle-exact 6502 core (65x02 oracle), VIA N+2, ULA one cell per cycle, PSG at clock/8, savestate as an exact resume point. Read the article →
Done
Core & peripherals
ORIC-1 / Atmos emulation, Microdisc/Sedoric, Jasmin, cassette, ACIA, DTL 2000, MIDI, LOCI (RP2040 firmware co-simulation).
Done
Native + WebAssembly
SDL2 builds (Linux / Windows / macOS) and browser, identical output; automatic release on tag.
Done
Hardware conformance
Line-by-line audit of the cores against manufacturer datasheets (WD1793, VIA 6522, PSG…). Still outside the model: FDC with fixed delays, VIA one-shot half-cycle.
In progress
ULA-NG → FPGA
Next-generation ULA (sprites, 80 columns, chunky 4bpp) as a software reference towards a Verilog / FPGA implementation.
In progress