diff --git a/README.md b/README.md
index 26c7352..9e84aee 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,9 @@ Any code I do for this [series](https://handmadehero.org) will be here.
 
 ## Scripts
 
-* `build.ps1` - Builds the project use `.\scripts\build msvc debug` or `.\scripts\build clang debug`. Add `optimize` for optimized builds.
+* `build.ps1` - Builds the project use `.\scripts\build msvc debug` or `.\scripts\build clang debug`. 
+  * `optimize` for optimized builds.
+  * `dev` for development builds. ( Dev memory layout and code paths compiled ).
 * `clean.ps1` - Cleans the project
 * `update_deps.ps1` - Updates the project dependencies to their latest from their respective repos. (Not done automatically on build)
 
diff --git a/docs/Day 015.md b/docs/Day 015.md
new file mode 100644
index 0000000..90485b2
--- /dev/null
+++ b/docs/Day 015.md	
@@ -0,0 +1,11 @@
+# Day 15
+
+Casey decides to restrict File IO to 32 bit limits for file size (under 4 gigs). This is due to a limitation do the win32 API in how much it can read into a provided buffer to `ReadFile` by the size of DWORD (4-bytes). For the purposes of this engine and problably almost all applications this is alright. 
+
+IF somehow more is needed, just reading in chunks of 4 gigs at a time is fine.
+
+I ended up watching a vod earlier recommended: Mysteries of Memory Management Revealed,with Mark Russinovich
+[Part 1](https://www.youtube.com/watch?v=TrFEgHr72Yg&t)
+[Part 2](https://www.youtube.com/watch?v=RsQyc4xiJeo)
+
+Was really nice, I got some of the equivalent info for linux.
diff --git a/project/engine.cpp b/project/engine.cpp
index ae66fa7..2fe426f 100644
--- a/project/engine.cpp
+++ b/project/engine.cpp
@@ -152,6 +152,19 @@ update_and_render( InputState* input, OffscreenBuffer* back_buffer, SoundBuffer*
 		state->XOffset = 0;
 		state->YOffset = 0;
 
+		#if Build_Debug
+		{
+			using namespace platform;
+
+			char* file_path = __FILE__;
+			Debug_FileContent file_content = debug_file_read_content( file_path );
+			if ( file_content.Size )
+			{
+				debug_file_write_content( "test.out", file_content.Size, file_content.Data );
+				debug_file_free_content( & file_content );
+			}
+		}
+		#endif
 	do_once_end
 
 	ControllerState* controller = & input->Controllers[0];
diff --git a/project/platform/handmade_win32.cpp b/project/platform/handmade_win32.cpp
index c4aa9a8..fa2f96a 100644
--- a/project/platform/handmade_win32.cpp
+++ b/project/platform/handmade_win32.cpp
@@ -67,7 +67,8 @@ ensure_impl( bool condition, char const* message ) {
 	JslSetLightColour( 0, (255 << 8 ) );                            \
 } while (0)
 
-NS_WIN32_BEGIN
+NS_PLATFORM_BEGIN
+using namespace win32;
 
 // TODO(Ed) : This is a global for now.
 global bool Running;
@@ -112,6 +113,83 @@ global s32                 DS_SecondaryBuffer_BytesPerSample;
 
 global s16* SoundBufferSamples;
 
+
+#if Build_Debug
+internal
+void debug_file_free_content( Debug_FileContent* content )
+{
+	if ( content->Data)
+	{
+		VirtualFree( content->Data, 0, MEM_Release);
+		*content = {};
+	}
+}
+
+internal
+Debug_FileContent debug_file_read_content( char* file_path )
+{
+	Debug_FileContent result {};
+
+	HANDLE file_handle = CreateFileA( file_path
+		, GENERIC_READ, FILE_SHARE_READ, 0
+		, OPEN_EXISTING, 0, 0
+	);
+	if ( file_handle == INVALID_HANDLE_VALUE )
+	{
+		// TODO(Ed) : Logging
+		return result;
+	}
+
+	GetFileSizeEx( file_handle, rcast(LARGE_INTEGER*, &result.Size) );
+	if ( result.Size == 0 )
+	{
+		// TODO(Ed) : Logging
+		return result;
+	}
+	result.Data = VirtualAlloc( 0, result.Size, MEM_Commit_Zeroed | MEM_Reserve, Page_Read_Write );
+
+	u32 bytes_read;
+	if ( ReadFile( file_handle, result.Data, result.Size, rcast(LPDWORD, &bytes_read), 0 ) == false )
+	{
+		// TODO(Ed) : Logging
+		return {};
+	}
+
+	if ( bytes_read != result.Size )
+	{
+		// TODO : Logging
+		return {};
+	}
+
+	CloseHandle( file_handle );
+	return result;
+}
+
+internal
+b32 debug_file_write_content( char* file_path, u32 content_size, void* content_memory )
+{
+	HANDLE file_handle = CreateFileA( file_path
+		, GENERIC_WRITE, 0, 0
+		, CREATE_ALWAYS, 0, 0
+	);
+	if ( file_handle == INVALID_HANDLE_VALUE )
+	{
+		// TODO : Logging
+		return false;
+	}
+
+	DWORD bytes_written;
+	if ( WriteFile( file_handle, content_memory, content_size, & bytes_written, 0 ) == false )
+	{
+		// TODO : Logging
+		return false;
+	}
+
+	CloseHandle( file_handle );
+	return true;
+}
+#endif
+
 internal void
 init_sound(HWND window_handle, s32 samples_per_second, s32 buffer_size )
 {
@@ -489,8 +567,6 @@ main_window_callback(
 	return result;
 }
 
-NS_WIN32_END
-
 internal void
 input_process_digital_btn( engine::DigitalBtn* old_state, engine::DigitalBtn* new_state, u32 raw_btns, u32 btn_flag )
 {
@@ -500,6 +576,8 @@ input_process_digital_btn( engine::DigitalBtn* old_state, engine::DigitalBtn* ne
 #undef had_transition
 }
 
+NS_PLATFORM_END
+
 int CALLBACK
 WinMain(
 	HINSTANCE instance,
@@ -509,6 +587,7 @@ WinMain(
 )
 {
 	using namespace win32;
+	using namespace platform;
 
 	// Memory
 	engine::Memory engine_memory {};
diff --git a/project/platform/platform.h b/project/platform/platform.h
index b0c14a4..75b9834 100644
--- a/project/platform/platform.h
+++ b/project/platform/platform.h
@@ -9,3 +9,26 @@
 #include "generics.h"
 #include "math_constants.h"
 #include "types.h"
+
+#define NS_PLATFORM_BEGIN namespace platform {
+#define NS_PLATFORM_END }
+
+NS_PLATFORM_BEGIN
+
+#if Build_Debug
+/*
+	IMPORTANT : These are not for shipping code - they are blocking and the write isn't protected.
+*/
+
+struct Debug_FileContent
+{
+	u32   Size;
+	void* Data;
+};
+
+void              debug_file_free_content ( Debug_FileContent* file_content );
+Debug_FileContent debug_file_read_content ( char* file_path );
+b32               debug_file_write_content( char* file_path, u32 content_size, void* content_memory );
+#endif
+
+NS_PLATFORM_END
diff --git a/project/platform/types.h b/project/platform/types.h
index e7874d4..a25e8e7 100644
--- a/project/platform/types.h
+++ b/project/platform/types.h
@@ -22,7 +22,7 @@
 #define S64_MIN ( -0x7fffffffffffffffll - 1 )
 #define S64_MAX 0x7fffffffffffffffll
 
-// Word size is the same as uw or size_t. This engine will not run on some weird compiler that doesn't
+// Word size is the same as uw or size_t. This platform will not run on some weird compiler that doesn't
 // Match the largest object to the word size of the architecture.
 #if defined( ARCH_64_BIT )
 #	define UWORD_MIN U64_MIN
@@ -104,4 +104,6 @@ typedef s8  b8;
 typedef s16 b16;
 typedef s32 b32;
 
+using mem_ptr = void*;
+
 #pragma endregion Basic Types