diff --git a/StateOS/README b/StateOS/README
index c7170b8c..bc10b6cd 100644
--- a/StateOS/README
+++ b/StateOS/README
@@ -35,6 +35,7 @@ Features:
 - added sys_alloc and sys_free procedures
 - updated cmsis-rtos and nasa-osal
 - added changes in some definitions
+- rebuilded kernel
 ---------
 4.3
 - rebuilded internal preprocessor definitions
diff --git a/StateOS/kernel/ARMCC/oscore.c b/StateOS/kernel/ARMCC/oscore.c
index b5af1ddc..7da06e7f 100644
--- a/StateOS/kernel/ARMCC/oscore.c
+++ b/StateOS/kernel/ARMCC/oscore.c
@@ -2,7 +2,7 @@
 
     @file    StateOS: oscore.c
     @author  Rajmund Szymanski
-    @date    21.12.2016
+    @date    25.01.2017
     @brief   StateOS port file for ARM Cotrex-M uC.
 
  ******************************************************************************
@@ -122,10 +122,12 @@ priv_ctx_exit
 __asm void core_tsk_flip( void *sp )
 {
 	PRESERVE8
-	IMPORT core_tsk_break
+	IMPORT core_ctx_switch
+	IMPORT core_tsk_start
 
 	mov   sp,    r0
-	bl    core_tsk_break
+	bl    core_ctx_switch
+	bl    core_tsk_start
 	
 	ALIGN
 }
diff --git a/StateOS/kernel/CLANG/oscore.c b/StateOS/kernel/CLANG/oscore.c
index c3db8ec4..e516ef17 100644
--- a/StateOS/kernel/CLANG/oscore.c
+++ b/StateOS/kernel/CLANG/oscore.c
@@ -2,7 +2,7 @@
 
     @file    StateOS: oscore.c
     @author  Rajmund Szymanski
-    @date    21.12.2016
+    @date    25.01.2017
     @brief   StateOS port file for ARM Cotrex-M uC.
 
  ******************************************************************************
@@ -121,12 +121,13 @@ void PendSV_Handler( void )
 /* -------------------------------------------------------------------------- */
 
 __attribute__((naked))
-void core_tsk_flip()
+void core_tsk_flip(/*void *sp*/)
 {
 	__asm volatile
 	(
 "	mov   sp,    r0                \n"
-"	bl    core_tsk_break           \n"
+"	bl    core_ctx_switch          \n"
+"	bl    core_tsk_start           \n"
 	
 :::	"memory"
 	);
diff --git a/StateOS/kernel/CSMCC/oscore.c b/StateOS/kernel/CSMCC/oscore.c
index 15562027..bb092a53 100644
--- a/StateOS/kernel/CSMCC/oscore.c
+++ b/StateOS/kernel/CSMCC/oscore.c
@@ -2,7 +2,7 @@
 
     @file    StateOS: oscore.c
     @author  Rajmund Szymanski
-    @date    21.12.2016
+    @date    25.01.2017
     @brief   StateOS port file for ARM Cotrex-M uC.
 
  ******************************************************************************
@@ -36,7 +36,6 @@
 void PendSV_Handler( void )
 {
 	#asm
-
 	xref  _core_tsk_handler
 
 #if __CORTEX_M < 3
@@ -123,11 +122,12 @@ priv_ctx_exit
 void core_tsk_flip( void *sp )
 {
 	#asm
-
-	xref  _core_tsk_break
+	xref  _core_ctx_switch
+	xref  _core_tsk_start
 
 	mov   sp,    r0
-	bl    _core_tsk_break
+	bl    _core_ctx_switch
+	bl    _core_tsk_start
 
 	#endasm
 }
diff --git a/StateOS/kernel/GNUCC/oscore.c b/StateOS/kernel/GNUCC/oscore.c
index 67f4dfae..62e87148 100644
--- a/StateOS/kernel/GNUCC/oscore.c
+++ b/StateOS/kernel/GNUCC/oscore.c
@@ -2,7 +2,7 @@
 
     @file    StateOS: oscore.c
     @author  Rajmund Szymanski
-    @date    21.12.2016
+    @date    25.01.2017
     @brief   StateOS port file for ARM Cotrex-M uC.
 
  ******************************************************************************
@@ -126,7 +126,8 @@ void core_tsk_flip( void *sp )
 	__asm volatile
 	(
 "	mov   sp,  %[sp]               \n"
-"	bl    core_tsk_break           \n"
+"	bl    core_ctx_switch          \n"
+"	bl    core_tsk_start           \n"
 	
 ::	[sp]"r"(sp)
 :	"memory"
diff --git a/StateOS/kernel/osbase.h b/StateOS/kernel/osbase.h
index 63ebc231..66ffabac 100644
--- a/StateOS/kernel/osbase.h
+++ b/StateOS/kernel/osbase.h
@@ -2,7 +2,7 @@
 
     @file    StateOS: osbase.h
     @author  Rajmund Szymanski
-    @date    13.01.2017
+    @date    25.01.2017
     @brief   This file contains basic definitions for StateOS.
 
  ******************************************************************************
@@ -126,22 +126,11 @@ typedef struct __sys
 
 typedef struct __ctx
 {
-	unsigned r4; // context saved by the software
-	unsigned r5;
-	unsigned r6;
-	unsigned r7;
-	unsigned r8;
-	unsigned r9;
-	unsigned r10;
-	unsigned r11;
-	unsigned exc; // EXC_RETURN
-
-	unsigned r0; // context saved by the hardware
-	unsigned r1;
-	unsigned r2;
-	unsigned r3;
-	void   * ip;
-	fun_t  * lr;
+	// context saved by the software
+	unsigned h[8]; // r4-r11
+	unsigned lr;   // EXC_RETURN
+	// context saved by the hardware
+	unsigned l[6]; // r0-r3,ip,lr
 	fun_t  * pc;
 	unsigned psr;
 
@@ -149,6 +138,27 @@ typedef struct __ctx
 
 /* -------------------------------------------------------------------------- */
 
+#define _CTX_INIT( pc ) { { 0 }, 0xFFFFFFFD, { 0 }, pc, 0x01000000 }
+
+__STATIC_INLINE
+void port_ctx_init( ctx_t *ctx, fun_t *pc )
+{
+	ctx->lr  = 0xFFFFFFFD; // EXC_RETURN: return from psp
+	ctx->pc  = pc;
+	ctx->psr = 0x01000000;
+}
+
+/* -------------------------------------------------------------------------- */
+
+// procedure inside ISR?
+__STATIC_INLINE
+unsigned port_isr_inside( void )
+{
+	return __get_IPSR();
+}
+
+/* -------------------------------------------------------------------------- */
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/StateOS/kernel/oskernel.c b/StateOS/kernel/oskernel.c
index 4e23c814..0dbead0b 100644
--- a/StateOS/kernel/oskernel.c
+++ b/StateOS/kernel/oskernel.c
@@ -2,7 +2,7 @@
 
     @file    StateOS: oskernel.c
     @author  Rajmund Szymanski
-    @date    22.01.2017
+    @date    26.01.2017
     @brief   This file provides set of variables and functions for StateOS.
 
  ******************************************************************************
@@ -49,8 +49,8 @@ static  struct { stk_t STK[ASIZE(OS_STACK_SIZE)]; } MAIN_STACK;
 #endif
 
 static  union  { stk_t STK[ASIZE(OS_STACK_SIZE)];
-        struct { char  stk[ASIZE(OS_STACK_SIZE)*sizeof(stk_t)-sizeof(ctx_t)]; ctx_t ctx; } CTX; } IDLE_STACK =
-               { .CTX={ .ctx={ .exc=0xFFFFFFFD, .lr=core_tsk_break, .pc=priv_tsk_idle, .psr=0x01000000 } } };
+        struct { char  stk[sizeof(stk_t[ASIZE(OS_STACK_SIZE)])-sizeof(ctx_t)]; ctx_t ctx; } CTX; } IDLE_STACK =
+               { .CTX = { .ctx = _CTX_INIT(core_tsk_start) } };
 #define IDLE_TOP &IDLE_STACK+1
 #define IDLE_SP  &IDLE_STACK.CTX.ctx
 
@@ -129,6 +129,17 @@ void core_tsk_remove( tsk_t *tsk )
 
 /* -------------------------------------------------------------------------- */
 
+void core_ctx_init( tsk_t *tsk )
+{
+	ctx_t *ctx = (ctx_t *)tsk->top - 1;
+
+	port_ctx_init(ctx, core_tsk_start);
+
+	tsk->sp = ctx;
+}
+
+/* -------------------------------------------------------------------------- */
+
 void core_ctx_switch( void )
 {
 	tsk_t *cur = IDLE.obj.next;
@@ -139,13 +150,13 @@ void core_ctx_switch( void )
 
 /* -------------------------------------------------------------------------- */
 
-void core_tsk_break( void )
+void core_tsk_start( void )
 {
 	for (;;)
 	{
-		core_ctx_switch();
 		port_clr_lock();
-		System.cur->state();
+		Current->state();
+		core_ctx_switch();
 	}
 }
 
@@ -297,20 +308,6 @@ void core_tsk_prio( tsk_t *tsk, unsigned prio )
 
 /* -------------------------------------------------------------------------- */
 
-void core_ctx_init( tsk_t *tsk )
-{
-	ctx_t *ctx = (ctx_t *)tsk->top - 1;
-
-	ctx->psr = 0x01000000;
-	ctx->pc  = tsk->state;
-	ctx->lr  = core_tsk_break;
-	ctx->exc = 0xFFFFFFFD; // EXC_RETURN: return from psp
-
-	tsk->sp  = ctx;
-}
-
-/* -------------------------------------------------------------------------- */
-
 void *core_tsk_handler( void *sp )
 {
 	tsk_t *cur, *nxt;
diff --git a/StateOS/kernel/oskernel.h b/StateOS/kernel/oskernel.h
index 16f8281b..1ece5152 100644
--- a/StateOS/kernel/oskernel.h
+++ b/StateOS/kernel/oskernel.h
@@ -2,7 +2,7 @@
 
     @file    StateOS: oskernel.h
     @author  Rajmund Szymanski
-    @date    24.01.2017
+    @date    25.01.2017
     @brief   This file defines set of kernel functions for StateOS.
 
  ******************************************************************************
@@ -52,9 +52,16 @@ void port_sys_init( void );
 
 /* -------------------------------------------------------------------------- */
 
+// init task 'tsk' for context switch
+void core_ctx_init( tsk_t *tsk );
+
 // save status of current process and force yield system control to the next
 void core_ctx_switch( void );
 
+// start current process
+__NO_RETURN
+void core_tsk_start( void );
+
 // reset context switch indicator
 __STATIC_INLINE
 void core_ctx_reset( void )
@@ -91,10 +98,6 @@ void core_tmr_handler( void );
 __NO_RETURN
 void core_tsk_flip( void *sp );
 
-// abort and reset current process and force yield system control to the next
-__NO_RETURN
-void core_tsk_break( void );
-
 // add task 'tsk' to tasks READY queue with id ID_READY
 // force context switch if priority of task 'tsk' is greater then priority of current task and kernel works in preemptive mode
 void core_tsk_insert( tsk_t *tsk );
@@ -152,10 +155,6 @@ void core_all_wakeup( void *obj, unsigned event );
 // force context switch if new priority of task 'tsk' is greater then priority of current task and kernel works in preemptive mode
 void core_tsk_prio( tsk_t *tsk, unsigned prio );
 
-// init task 'tsk' stack
-// prepare stack the starting task for context switch
-void core_ctx_init( tsk_t *tsk );
-
 // tasks queue handler procedure
 // save stack pointer 'sp' of the current task
 // reset context switch timer counter
@@ -164,15 +163,6 @@ void *core_tsk_handler( void *sp );
 
 /* -------------------------------------------------------------------------- */
 
-// procedure inside ISR?
-__STATIC_INLINE
-unsigned port_isr_inside( void )
-{
-	return __get_IPSR();
-}
-
-/* -------------------------------------------------------------------------- */
-
 #ifdef __cplusplus
 }
 #endif