RPCEmu – Debugger & Inspector Edition

Overview

This repository hosts a feature-rich fork of RPCEmu, the open-source emulator for Acorn Risc PC and A7000 machines. Alongside the standard emulator core, this edition layers in a modern Qt 5 front-end, a live machine inspector, integrated debugger controls. The project remains distributed under the GNU GPL v2.

Fork highlights

• Machine Inspector window – Inspect CPU registers, pipeline state, MMU flags, performance counters, and key peripheral snapshots (VIDC, SuperIO, IDE, podules) with optional auto-refresh.
• Integrated debugger – Pause/resume execution, single-step (×1/×5), and manage breakpoints and watchpoints directly in the GUI, with clear status readouts for the last halt reason.
• Dynarec-aware instrumentation – The ARM dynamic recompiler honours debugger pause requests, breakpoints, and watchpoints via shared hooks (debugger_requires_instruction_hook) so that interpreter and dynarec stay in sync.
• Snapshot plumbing – Thread-safe MachineSnapshot and peripheral snapshot structs marshal detailed state off the emulator thread for UI consumption without stalls.

Project layout

Path	Purpose
src/	Core emulator engine (ARM interpreter, dynarec, hardware devices, debugger plumbing).
src/qt5/	Qt 5 GUI, machine inspector, debugger controls, configuration & networking dialogs.
slirp/	Bundled SLiRP networking library for NAT mode.
hostfs/, poduleroms/, riscos-progs/	Support utilities, ROM stubs, and example binaries for HostFS/podule integration.
roms/	Place your licensed RISC OS ROM images here (see official instructions).

Using the debugger & machine inspector

1. Open Debug → Machine Inspector… to reveal the inspector window.
2. Tabs provide:
   • CPU – Registers R0–R15, CPSR/mode, performance counters, interpreter vs dynarec state.
   • Pipeline – Upcoming instruction addresses and opcodes for easy tracing.
   • Peripherals – VIDC palette & doublescan mode, SuperIO registers, IDE channel state, podule IRQ mapping.
   • Debugger – Run/Pause, Step, Step ×5 buttons, breakpoint & watchpoint lists, last hit summaries.
3. Auto-refresh every 500 ms keeps the view current; toggle it or hit Refresh now for manual polling.
4. Breakpoints and watchpoints entered in the inspector apply even while the dynarec is active, thanks to the shared debugger hooks in ArmDynarec.c.

Differences versus upstream RPCEmu

• Qt front-end reworked for stability with modern Qt 5 deployments.
• In-depth machine inspector and debugger tooling not present upstream.
• Dynarec pause logic patched so debugger operations are consistent across cores.

Troubleshooting

Symptom	Remedy
Emulator launches without a window	Ensure Qt 5 runtime libs are discoverable; this fork delays snapshot requests to avoid deadlock, so missing Qt plugins are the usual culprit.
No network connectivity	Confirm SLiRP support was compiled in (CONFIG_SLIRP) and NAT rules are configured.

Contributing

Issues and pull requests are welcome, especially around debugger/inspector features.

License & credits

• Licensed under the GNU General Public License v2. See COPYING for details.
• Original emulator by the RPCEmu contributors.
• Debugger, inspector, and stability enhancements developed within this fork to support modern RISC OS development workflows.