Set vga_monoscope default boot mode to PAL 720x576 and add build instructions

BUILD_INSTRUCTIONS.md

@@ -0,0 +1,61 @@
+# Build Instructions
+
+This project uses CMake with the Raspberry Pi Pico SDK and an ARM cross-toolchain.
+
+## Prerequisites (Ubuntu/Debian)
+
+Install required packages:
+
+```bash
+sudo apt-get update
+sudo apt-get install -y \
+  cmake \
+  ninja-build \
+  gcc-arm-none-eabi \
+  binutils-arm-none-eabi
+```
+
+## Configure
+
+From the repository root:
+
+```bash
+cmake -S . -B build -G Ninja -DPICO_SDK_FETCH_FROM_GIT=ON
+```
+
+Notes:
+- `PICO_SDK_FETCH_FROM_GIT=ON` automatically downloads the Pico SDK into `build/_deps`.
+- If you already have a local Pico SDK, set `PICO_SDK_PATH` instead.
+
+## Build the Monoscope Example
+
+```bash
+cmake --build build --target vga_monoscope -j
+```
+
+## Output Artifacts
+
+After a successful build, files are generated here:
+
+- `build/examples/vga_monoscope/vga_monoscope.uf2`
+- `build/examples/vga_monoscope/vga_monoscope.hex`
+- `build/examples/vga_monoscope/vga_monoscope.bin`
+- `build/examples/vga_monoscope/build/vga_monoscope.elf`
+
+## Rebuild
+
+To rebuild after source changes:
+
+```bash
+cmake --build build --target vga_monoscope
+```
+
+## Clean Build
+
+To start from a clean state:
+
+```bash
+rm -rf build
+cmake -S . -B build -G Ninja -DPICO_SDK_FETCH_FROM_GIT=ON
+cmake --build build --target vga_monoscope -j
+```

examples/vga_monoscope/src/main.cpp

@@ -53,7 +53,7 @@
 
 u16 Rows[962];	// RLE rows
 u8 Img[180000] __attribute__ ((aligned(4))); // RLE image
-int MonoSel = 22; // selected videomode
+int MonoSel = 1; // selected videomode (PAL 720x576)
 
 // monoscope descriptor
 typedef struct {
@@ -262,8 +262,8 @@ int main()
 	// run VGA core
 	StartVgaCore();
 
-	// run default video mode VGA 640x480
-	MonoInit(22);
+	// run default video mode PAL 720x576
+	MonoInit(1);
 
 	while (true)
 	{