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README.md

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+# emulator
+
+A simple emulator built in C++17 using SDL2 for video/audio. It loads a ROM
+file from disk, maps it into memory, and runs a fetch/decode/execute loop
+rendered to an SDL window.
+
+## Prerequisites
+
+- **C++17 compiler** — MSVC (Visual Studio 2019 or 2022 Build Tools) on
+  Windows. The project is currently configured for the MSVC toolchain.
+- **CMake** 3.21 or newer (required for the CMake Presets feature).
+- **Ninja** — used as the build generator.
+- **vcpkg** — dependencies are declared in `vcpkg.json` (manifest mode), so
+  vcpkg fetches them automatically on first configure. A working vcpkg
+  installation must be available on the system.
+- **Git** — for cloning and for vcpkg to fetch package sources.
+
+## Project layout
+
+```
+.
+├── CMakeLists.txt        # build definition
+├── CMakePresets.json     # configure/build presets (vcpkg + MSVC + Ninja)
+├── vcpkg.json            # dependency manifest (sdl2, sdl2-image)
+├── .vscode/              # editor / IntelliSense config
+├── src/
+│   ├── main.cpp          # entry point: parses argv, runs the emulator
+│   ├── emulator.hpp      # Emulator class declaration
+│   └── emulator.cpp      # Emulator class implementation
+└── build/                # generated after configure (gitignored)
+```
+
+## Installation
+
+1. **Clone the repository**
+
+   ```sh
+   git clone <repo-url> emulator
+   cd emulator
+   ```
+
+2. **Ensure vcpkg is installed**
+
+   If you do not already have vcpkg, clone and bootstrap it:
+
+   ```sh
+   git clone https://github.com/microsoft/vcpkg.git
+   cd vcpkg
+   .\bootstrap-vcpkg.bat
+   ```
+
+   Note its root path — you will reference it in the next step.
+
+3. **Point CMake at the vcpkg toolchain**
+
+   `CMakePresets.json` sets `CMAKE_TOOLCHAIN_FILE` to:
+
+   ```
+   C:/Program Files (x86)/Microsoft Visual Studio/18/BuildTools/VC/vcpkg/scripts/buildsystems/vcpkg.cmake
+   ```
+
+   If your vcpkg lives elsewhere, edit the `default` configure preset
+   (or create a `CMakeUserPresets.json` next to `CMakePresets.json`) so the
+   `CMAKE_TOOLCHAIN_FILE` value matches your vcpkg install.
+
+## Setup & build
+
+Configure and build with the bundled preset (uses vcpkg manifest mode, so
+`sdl2` and `sdl2-image` are installed automatically on first configure):
+
+```sh
+cmake --preset default
+cmake --build --preset default
+```
+
+The resulting executable is placed in `build/` (e.g. `build/emulator.exe`).
+
+## Running
+
+Pass a ROM file as the only argument:
+
+```sh
+.\build\emulator.exe <rom-file>
+```
+
+Press **Esc** or close the window to quit.
+
+## Editor / IntelliSense
+
+VS Code IntelliSense is configured in `.vscode/c_cpp_properties.json` to read
+`build/compile_commands.json` (generated by the `default` preset). Configure
+the project once with `cmake --preset default` so the compile database exists;
+IntelliSense will then resolve `SDL.h` and the project headers correctly.