68mixCross

68mixCross is a cross-platform “dev BBS / chat” stack: a Rust TCP hub (mixnetd) and thin C clients (desktop, Amiga, console) that all speak the same line-based mixnet v0 protocol. The same design ties a Sega Mega Drive ROM and console bridges (e.g. N64, PlayStation 1 text shell) to one server—so you can hack rooms, nicks, and wire protocol on the PC, then point hardware or emulators at the same hub.

Layer	What you get
Server	server/ — mixnetd (TCP; default 19677). The core product for local dev and “LAN party” BBS style sessions.
Genesis (optional)	clients/genesis/ — SGDK serial terminal ROM: scrollback chat UI + on-screen keyboard over 4800 bps serial → PC bridge → mixnetd. ROM: clients/genesis/out/rom.bin via root build.bat / build.ps1.
PS1 (PSYQ)	clients/psx/ — Mixnet Navigator: text UI shell for the same protocol, built for CCPSX; see clients/psx/README.md and clients/psx/BUILD-PS1.md.
Other clients	Win9x, POSIX, Amiga, more stubs in clients/; shared framing in clients/common/, constants in clients/include/.

At a glance

• You can work on BBS / chat and mixnetd without building the Genesis ROM; see docs/REPO_LAYERS.md. External SDK setup (PSYQ, etc.): docs/TOOLCHAINS.md. AI/editor index: .cursor/entry-point.mdc.

Repository layout

Path	Purpose
clients/genesis/	Sega client: SGDK project (src/, res/, inc/), out/rom.bin, plus mixnet_line.c / mixnet_line.h
_compilers/	Bundled or linked toolchains; SGDK copy under _compilers/sgdk (optional)
build/	Extra build logs / ASM68K outputs (artifacts gitignored)
server/	mixnetd — TCP protocol v0 + extensions — server/README.md
clients/	Amiga (full TCP), Win9x (full TCP), POSIX (full TCP), Genesis (ROM + line layer), N64 (stub), PSX (full serial UI: Mixnet Navigator), PS2 (placeholder); shared headers & framing — clients/README.md
docs/	Index, changelog, toolchains, repo layers
.cursor/	AI/editor documentation (protocol, platforms, 68k)

Protocol: .cursor/.documentation/cross-net/protocol-v0.mdc

Requirements

• Genesis ROM: SGDK (GNU make, m68k-elf-gcc toolchain inside SGDK). Set GDK_WIN to the SGDK root (folder containing bin\make.exe and makefile.gen). If you use a copy in-repo, the default is \_compilers\sgdk.
• mixnetd: Rust (cargo on PATH) and, on Windows with the GNU target, a MinGW bin directory on PATH (e.g. MSYS2 at D:\__SDKs Modding\msys64) — see server/.cargo/config.toml and server/build-mingw.ps1. Override with MSYS2_ROOT.

Build (Windows)

From the repository root (not server\ alone):

Command	Action
build.bat or build.bat genesis (alias: make_rom.bat)	SGDK release → clients\genesis\out\
build.bat server	mixnetd via build.ps1
build.bat all	Genesis + server
build.bat clean	Remove common clients/genesis/out/, build/, server/target artifacts
.\build.ps1	Same with -Target All / Genesis / Server / Clean / Asm68k

cmd.exe (not PowerShell) for one-off:

set "GDK_WIN=E:\path\to\sgdk"
build.bat

Build (PowerShell) examples

cd <path-to>\68mixCross
$env:GDK_WIN = "E:\Emulation\sgdk211"   # if not using _compilers\sgdk
$env:MSYS2_ROOT = "D:\__SDKs Modding\msys64"  # if MinGW is not on PATH
.\build.ps1 -Target All

mixnetd run

server\target\x86_64-pc-windows-gnu\release\mixnetd.exe

Optional: MIXNETD_IDLE_SEC=600 to drop idle TCP sessions. Default listen port: 19677 (or pass a port as the first argument).

Client implementation status

Client	Path	Type	Status
Win9x	clients/win9x/mixnet.c	Direct TCP (Winsock 1.1)	Full client with threads, all verbs, :quit
POSIX	clients/posix/mixnet.c	Direct TCP (BSD sockets)	Full client with pthreads, all verbs
Amiga	clients/amiga/mixnet.c	Direct TCP (AmigaOS sockets)	Full client (same model as POSIX)
PS1	clients/psx/	SIO1 serial ↔ PC bridge	Full UI (Mixnet Navigator: text browser with scrollback, Location bar, menu keys); real SIO1 at 115200 8N1
Genesis	clients/genesis/	Serial cart/GPIO ↔ PC bridge	Re-exports mixnet_line framing; needs UART ISR wiring by developer
N64	clients/n64/mixnet_stub.c	Serial/USB ↔ PC bridge	Stub with self-test; mixnet_on_server_line is empty — user must wire UART/PI FIFO
PS2	clients/ps2/mixnet_stub.c	TCP or bridge (TBD)	Placeholder (int main(){ return 0; }) — needs PS2SDK + ps2ip/lwIP
Bridge	clients/bridge/mixnet_serial_bridge.py	Serial ↔ TCP relay	Fully functional; two daemon threads, supports physical COM or emulator TCP tunnel

Build commands (from repo root):

Client	Command
Win32 (MinGW)	gcc -std=c99 -O2 -Wall -o clients/win9x/mixnet.exe clients/win9x/mixnet.c -lwsock32
POSIX	cc -O2 -pthread -o mixnet clients/posix/mixnet.c
Amiga	m68k-amigaos-gcc -O2 -std=c99 -o mixnet clients/amiga/mixnet.c -lpthread -lsocket

All direct-TCP clients accept: mixnet <host> <port> [nick] [room] — :quit to send QUIT.

Serial bridging (console → PC → mixnetd)

Consoles without TCP/IP (Genesis, PS1, N64) connect via serial to a PC running mixnet_serial_bridge.py, which relays bytes to and from mixnetd.

Console (UART/SIO)  ──serial──▶  bridge.py  ──TCP──▶  mixnetd (port 19677)
     ▲                            (bi-directional        ▲
     └──── serial byte pipe ────── byte relay) ──────────┘

• Bridge is framing-agnostic — it chunks serial and TCP data in 4096-byte blocks. Line framing (\n delimiting) is handled entirely on the console side via clients/common/mixnet_line.c.
• Two serial modes: --serial COM3 --baud 115200 (physical) or --serial-tcp 127.0.0.1:5678 (emulator tunnel for DuckStation/PCSX-Redux).
• Any RS-232C device (Amiga, X68000, PC-98) can reuse the same bridge unchanged — just port mixnet_line.c with a platform UART driver.
• Python bridge: pip install -r clients/bridge/requirements.txt; run python clients/bridge/mixnet_serial_bridge.py --serial COM3 --server 127.0.0.1 --port 19677.
• Serial pinouts & wiring: see docs/SERIAL-HARDWARE.md for PS1 SIO1, Amiga RS-232, and Genesis flashcart serial pinouts plus the packet opcode catalog.

Platform coverage / future

Platform	CPU	Direct TCP	Serial bridge	Notes
Windows 9x+	x86	✅ Win9x client	—	Winsock 1.1
Linux / macOS	x86/ARM	✅ POSIX client	—	BSD sockets + pthreads
Amiga (OS 3.x)	68000	✅ Amiga client	✅ (via RS-232)	AmiTCP/Roadshow
PlayStation 1	R3000	❌	✅ PS1 SIO1 + Navigator UI	Full text shell
Mega Drive/Genesis	68000	❌	✅ via mixnet_line	Needs UART cart (EverDrive, etc.)
Nintendo 64	R4300	❌	✅ stub (empty callback)	Needs UART/64Drive/PI FIFO driver
PlayStation 2	EE	❌ placeholder	❌	Needs PS2SDK + ps2ip/lwIP
X68000	68000	❌	✅ (easy — RS-232C built-in)	No client code yet; build-68mix.sh already outputs out/x68000/ozworld.x demo binary
PC-98	x86/V30	❌	✅ (easy — RS-232C built-in)	No client code yet; needs x86 C (unlike rest of repo)

Shortest path to add a platform: serial bridge. Port clients/common/mixnet_line.c (pure C89, CPU-agnostic) with a UART putbyte/getbyte driver. The Python bridge and mixnetd need zero changes.

Full cross-asm script (Unix / Git Bash)

build-68mix.sh can drive extra targets (WSL, vasm, Amiga, X68000); it expects a Unix-like environment and your own toolchains. It also copies clients/genesis/src/ozworld_68mix.s (gitignored) during the run.

Git

Upstream (this worktree): github.com/odelyzid/cross-dev-net

Use the root .gitignore and .gitattributes. Do not commit clients/genesis/out/, build/genesis binaries, clients/genesis/src/ozworld_68mix.s, or server/target/. One repo at the project root — do not add a nested server/.git.

To publish from a fresh clone (or a tree without origin yet):

git status   # ensure build artifacts stay untracked
git remote add origin https://github.com/odelyzid/cross-dev-net.git
git branch -M main
git push -u origin main

License

See per-component toolchains (SGDK, etc.). Application source in this tree is offered as-is for porting and learning; add a license file when you pick one for your fork.