diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..ad4f671
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,49 @@
+# Changelog
+
+All notable changes to **RP2040Sharp** are documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [1.0.0-rc.1] - 2026-06-06
+
+First public release candidate. A high-performance RP2040 emulator in modern C#
+(.NET 10) that runs real, unmodified firmware including MicroPython. C# port of
+[rp2040js](https://github.com/wokwi/rp2040js) by Uri Shaked.
+
+### Added
+
+- **ARM Cortex-M0+ core** — full Thumb-1 instruction set, exceptions, NVIC,
+  SysTick and PendSV, with an O(1) flat-table instruction decoder.
+- **Dual-core support** — Core 1 launches through the SIO FIFO multicore
+  handshake (RP2040 §2.8.3); both cores advance in lock-step.
+- **GDB Remote Serial Protocol server** — debug Core 0 with `arm-none-eabi-gdb`
+  via `target remote :3333` (registers, memory, single-step, breakpoints,
+  detach). The demo accepts a `--gdb` flag.
+- **Real RP2040 B1 BootROM** embedded as a resource; ROM table lookups and
+  bit-manipulation helpers run natively.
+- **Flash erase/program** through native C# hooks, so MicroPython's LittleFS
+  filesystem works correctly.
+- **MicroPython** boots to an interactive REPL over emulated USB-CDC.
+- **Peripherals** — GPIO, SIO (spinlocks, interpolators, hardware divider),
+  UART0/1, SPI0/1, I2C0/1 (master and slave-mode simulation), ADC, PWM (all 8
+  slices), PIO0/1 (state machines + GPIO), DMA (all channels, DREQ sources),
+  Timer/Alarms, Watchdog, RTC, USB CDC-ACM host, Clocks and Resets.
+- **Per-pin GPIO API** (`SetGpioExternalIn`, `GetGpioOut`,
+  `GetGpioOutputEnable`) for embedding in circuit simulators.
+- **RP2040Sharp.TestKit** — a fluent harness for writing firmware integration
+  tests.
+- NuGet packaging for `RP2040Sharp` and `RP2040Sharp.TestKit` (AOT-compatible,
+  trimmable), versioned automatically from git tags via MinVer.
+
+### Known limitations
+
+- XOSC, ROSC, PLL, PSM and VREG are register stubs (report stable/locked; no
+  frequency model).
+- Flash programming uses C# hooks rather than the SSI XIP hardware path.
+- USB host support is CDC-only (sufficient for the MicroPython REPL).
+
+[Unreleased]: https://github.com/begeistert/RP2040Sharp/compare/v1.0.0-rc.1...HEAD
+[1.0.0-rc.1]: https://github.com/begeistert/RP2040Sharp/releases/tag/v1.0.0-rc.1