diff --git a/C Compiler.md b/SDK.md
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rename to SDK.md
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-# C Compiler
+# SDK
+
+The Sentinel 65X software development kit is a package of tools and resources used in cross-development of programs for Sentinel 65X.
+
+## C Compiler
 
 The cross-development SDK for Sentinel 65X requires the Calypsi C/asm toolchain, targeting 65816. The SDK does not include Calypsi, which is available as freeware from [the Calypsi website](https://calypsi.cc).