diff --git a/include/firm/os/common/system.h b/include/firm/os/common/system.h
new file mode 100644
index 00000000..2cdd5f8c
--- /dev/null
+++ b/include/firm/os/common/system.h
@@ -0,0 +1,53 @@
+/*---------------------------------------------------------------------------*
+  Project:  TwlSDK - OS - include
+  File:     system.h
+
+  Copyright 2007 Nintendo.  All rights reserved.
+
+  These coded instructions, statements, and computer programs contain
+  proprietary information of Nintendo of America Inc. and/or Nintendo
+  Company Ltd., and are protected by Federal copyright law.  They may
+  not be disclosed to third parties or copied or duplicated in any form,
+  in whole or in part, without the prior written consent of Nintendo.
+
+  $Log: $
+  $NoKeywords: $
+ *---------------------------------------------------------------------------*/
+#ifndef TWL_FIRM_OS_SYSTEM_H_
+#define TWL_FIRM_OS_SYSTEM_H_
+
+#include <twl/misc.h>
+#include <twl/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//----------------------------------------------------------------------------
+
+typedef u32 OSCpuCycle;
+
+#define OS_CPU_CLOCK                   HW_CPU_CLOCK
+
+//---- sec to cpu cycle
+// 150nsec - 30sec
+#define  OS_SEC_TO_CPUCYC(  sec  ) ((OSCpuCycle)( ( OS_CPU_CLOCK * (u32)(sec)) ))
+#define  OS_MSEC_TO_CPUCYC( msec ) ((OSCpuCycle)( ((OS_CPU_CLOCK/1000) * (u32)(msec)) ))
+#define  OS_USEC_TO_CPUCYC( usec ) ((OSCpuCycle)( ((OS_CPU_CLOCK/1000) * (u32)(usec)) / 1000 ))
+#define  OS_NSEC_TO_CPUCYC( nsec ) ((OSCpuCycle)( ((OS_CPU_CLOCK/1000) * (u32)(nsec)) / (1000 * 1000) ))
+
+//---- cpu cycle to sec
+// 150nsec - 30sec
+#define  OS_CPUCYC_TO_SEC(  cyc ) ( ((u32)(cyc) ) / OS_CPU_CLOCK )
+#define  OS_CPUCYC_TO_MSEC( cyc ) ( ((u32)(cyc) ) / (OS_CPU_CLOCK/1000) )
+#define  OS_CPUCYC_TO_USEC( cyc ) ( ((u32)(cyc) * 1000) / (OS_CPU_CLOCK/1000) )
+#define  OS_CPUCYC_TO_NSEC( cyc ) ( ((u32)(cyc) * 1000 * 1000) / (OS_CPU_CLOCK/1000) )
+
+
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+/* TWL_FIRM_OS_SYSTEM_H_ */
+#endif