diff --git a/src/vm.h b/src/vm.h
new file mode 100644
index 0000000..1ed2051
--- /dev/null
+++ b/src/vm.h
@@ -0,0 +1,49 @@
+#ifndef _VM_H
+#define _VM_H
+
+
+/*
+  PIDLE
+  PRUNNING
+  PRUNNING|PHANDLER
+  PSUSPENDED
+  PSUSPENDED|PHANDLER
+  PTIMEOUT|PINTERRUPT
+  PTIMEOUT|PINTERRUPT|PEVENTPEND
+  ...
+*/
+
+typedef enum {
+  PIDLE      = 1,     // Nothing todo
+  PRUNNING   = 2,     // Running in main program
+  PSUSPENDED = 4,     // Suspended (stopped, but still servicing events)
+  PTIMEOUT   = 8,     // Delay (if not EVENTPEND) or awaiting event with timeout
+  PAWAIT     = 16,    // awaiting event, internal (e.g. blocke IN/OUT op) or external event
+  PINTERRUPT = 32,    // Main program is interrupted by delay/await, but not stopped
+  PHANDLER   = 64,    // Running in (event) handler
+  PERROR     = 128,   // Processing error (or in error state) and running error handler
+  PEVENTPEND = 256    // pending events to be handled
+} vm_states_t;
+
+
+#include "mem.h"
+#include "reg.h"
+#include "stack.h"
+#include "context.h"
+
+/*
+  A reason to enter VM run?
+*/
+#define RUNNABLE(R)  (R->state&(PRUNNING|PHANDLER|PEVENTPEND))
+/*
+  Execute at least one VM instruction?
+*/
+#define RUNNABLE1(R)  (R->state&(PRUNNING|PHANDLER))
+
+int  Run(context_t *C);
+void CodeCleanUp(context_t *C);
+int  Start(context_t *C);
+int  Stop(context_t *C);
+int  Suspend(context_t *C, index_t type, index_t io, index_t tinmeout);
+
+#endif