Releases

X16Emu ADD is the Advanced Disassembler and Debugger, a fork of the official Commander X16 emulator.

Releases are named R<major>.<nnn>:

• R<major> names the official Commander X16 release line the build follows. That half of the number is upstream's, and so are its release notes — they are not reproduced here. Read them at X16Community/x16-emulator/releases, e.g. r49 ("Pyrite").
• nnn counts the ADD builds on top of that line. Those are the changes listed below.

R49 means the build follows the R49 line, not that it is byte-for-byte official R49: the emulator core tracks upstream's ongoing development after that release, so a build may include upstream fixes made since R49 was cut. Each release package ships the rom.bin it was built and tested against — use that one.

R49.001

The first ADD release, following the upstream R49 line. Everything here is new relative to the official emulator.

Graphical debugger (-imgui)

• New Dear ImGui debug window with a dockable, rearrangeable layout that is saved between runs
• Disassembly panel with effective-address tooltips, run-to-here and breakpoint toggling
• CPU panel: registers with 65C816-aware widths, decoded flags, the stack, the X16 virtual registers R0–R15, and user-defined address watches
• Memory panel: hex editor over CPU space, banked RAM and VRAM, with range selection, hex/ASCII search, changed-byte highlighting, and break-on-write straight from a selection
• Source panel: original cc65 source in tabs, current line highlighted and centred on each stop, breakpoints settable before the PC ever reaches the code
• VERA panel: palette, tile, sprite, bitmap and tilemap viewers, plus all 32 registers decoded per scanline so raster splits are visible rather than flattened
• PSG, YM2151 and PCM panels with scope traces that keep drawing while the machine is paused
• Symbols, Call Stack and Breakpoints panels; the call stack names frames by nearest label, so code without debug info still reads sensibly
• Toolbar with run/step controls, an absolute clock-speed readout (red above native speed) and a warp toggle; status line showing run state, IRQ nesting depth, 24-bit PC, cycles and instructions

Remote debugging (-debugport)

• New Debug Adapter Protocol server over TCP, default port 9009, for VS Code, Visual Studio or any other DAP-compliant client
• Breakpoints, stepping, stack traces, scopes, variables, memory read/write and disassembly
• VRAM read and write through readMemory/writeMemory with a vram: reference, reaching VERA's 17-bit space that the CPU map cannot address
• Conditional breakpoints on registers and memory (A == $05, byte[$1234] != 0), bank-pinned conditions (bank == 2), and hit counts
• Expression evaluation covering registers, memory, cc65 labels and equates, VRAM, and VERA registers — including vera_line, which reports the registers that actually rendered a given scanline
• Scriptable keyboard, text and joystick input, making automated regression runs practical. The virtual SNES controllers need no gamepad attached and no -joy1..-joy4 flag, so a headless CI machine can drive a game that reads the controller ports
• tools/x16dbg, a .NET command-line DAP client with one-shot and interactive modes

Source-level debugging (-dbgfile, -srcpath)

• cc65 .dbg parsing: addresses map back to source files, lines, labels and equates
• .dbg files auto-load alongside the program they belong to, including for modules the running program LOADs at runtime, so debugging follows execution into overlays
• Breakpoints are invalidated when a module unloads and re-resolved when one loads back in
• Banked code in $A000–$BFFF is attributed to the correct RAM bank at runtime, so source mapping and breakpoints stay correct across bank switches

Debugger capacity

• Memory write watchpoints, up to 64 of them
• 65C816 / GS support throughout: 24-bit bank:address browsing and mode-correct register widths

Windows

• Statically linked MSVC builds for x64, x86 and ARM64 — a single self-contained x16emu.exe with no SDL2, zlib or Visual C++ redistributable to install
• Separate MIDI builds shipping FluidSynth, for those who want it
• The emulator keeps running and painting while its window is dragged or resized, instead of freezing for the duration

Build and release

• Every push is built for all platforms; pushing an R<major>.<nnn> tag stages a draft release with every platform asset attached, ready for a human to publish, and the default branch keeps a rolling dev prerelease
• ROM images are fetched with a fallback to the latest release when the upstream build artifact has expired

Known limitations

• The debugger and DAP server are experimental — expect keys, layouts and DAP details to change
• The WebAssembly build is not tested with the debugger or the DAP server
• MSVC builds have no -trace; use a -mingw package if you need it
• Upstream's original -debug debugger is still present but is not extended by ADD