diff --git a/sim/common/.Sanitize b/sim/common/.Sanitize
index 240f3d3bd7..2948748dc2 100644
--- a/sim/common/.Sanitize
+++ b/sim/common/.Sanitize
@@ -65,6 +65,10 @@ hw-device.c
 hw-device.h
 hw-events.c
 hw-events.h
+hw-handles.c
+hw-handles.h
+hw-instances.c
+hw-instances.h
 hw-main.h
 hw-ports.c
 hw-ports.h
diff --git a/sim/common/hw-handles.c b/sim/common/hw-handles.c
new file mode 100644
index 0000000000..a62c015514
--- /dev/null
+++ b/sim/common/hw-handles.c
@@ -0,0 +1,237 @@
+/*  This file is part of the program psim.
+
+    Copyright (C) 1994-1995,1997-1998, Andrew Cagney <cagney@highland.com.au>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+ 
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ 
+    */
+
+
+#include "hw-main.h"
+#include "hw-base.h"
+
+
+struct hw_handle_mapping {
+  cell_word external;
+  struct hw *phandle;
+  struct hw_instance *ihandle;
+  struct hw_handle_mapping *next;
+};
+
+
+struct hw_handle_data {
+  int nr_mappings;
+  struct hw_handle_mapping *mappings;
+};
+
+void
+create_hw_handle_data (struct hw *hw)
+{
+  if (hw_parent (hw) == NULL)
+    {
+      hw->handles_of_hw = HW_ZALLOC (hw, struct hw_handle_data);
+    }
+  else
+    {
+      hw->handles_of_hw = hw_root (hw)->handles_of_hw;
+    }
+}
+
+void
+delete_hw_handle_data (struct hw *hw)
+{
+  /* NULL */
+}
+
+
+
+#if 0
+void
+hw_handle_init (struct hw *hw)
+{
+  struct hw_handle_mapping *current_map = db->mappings;
+  if (current_map != NULL)
+    {
+      db->nr_mappings = db->mappings->external;
+      /* verify that the mappings that were not removed are in
+	 sequence down to nr 1 */
+      while (current_map->next != NULL)
+	{
+	  if (current_map->external != current_map->next->external + 1)
+	    error ("hw_handle: hw_handle database possibly corrupt");
+	  current_map = current_map->next;
+	}
+      ASSERT (current_map->next == NULL);
+      if (current_map->external != 1)
+	error ("hw_handle: hw_handle database possibly corrupt");
+    }
+  else
+    {
+      db->nr_mappings = 0;
+    }
+}
+#endif
+
+
+struct hw_instance *
+hw_handle_ihandle2 (struct hw *hw,
+		    cell_word external)
+{
+  struct hw_handle_data *db = hw->handles_of_hw;
+  struct hw_handle_mapping *current_map = db->mappings;
+  while (current_map != NULL)
+    {
+      if (current_map->external == external)
+	return current_map->ihandle;
+      current_map = current_map->next;
+    }
+  return (void*)0;
+}
+
+
+struct hw *
+hw_handle_phandle2 (struct hw *hw,
+		    cell_word external)
+{
+  struct hw_handle_data *db = hw->handles_of_hw;
+  struct hw_handle_mapping *current_map = db->mappings;
+  while (current_map != NULL)
+    {
+      if (current_map->external == external)
+	return current_map->phandle;
+      current_map = current_map->next;
+    }
+  return (void*)0;
+}
+
+
+cell_word
+hw_handle_2ihandle (struct hw *hw,
+		    struct hw_instance *internal)
+{
+  struct hw_handle_data *db = hw->handles_of_hw;
+  struct hw_handle_mapping *current_map = db->mappings;
+  while (current_map != NULL)
+    {
+      if (current_map->ihandle == internal)
+	return current_map->external;
+      current_map = current_map->next;
+    }
+  return 0;
+}
+
+
+cell_word
+hw_handle_2phandle (struct hw *hw,
+		    struct hw *internal)
+{
+  struct hw_handle_data *db = hw->handles_of_hw;
+  struct hw_handle_mapping *current_map = db->mappings;
+  while (current_map != NULL)
+    {
+      if (current_map->phandle == internal)
+	return current_map->external;
+      current_map = current_map->next;
+    }
+  return 0;
+}
+
+
+void
+hw_handle_add_ihandle (struct hw *hw,
+		       struct hw_instance *internal)
+{
+  struct hw_handle_data *db = hw->handles_of_hw;
+  if (hw_handle_2ihandle (hw, internal) != NULL) 
+    {
+      hw_abort (hw, "attempting to add an ihandle already in the data base");
+    }
+  else
+    {
+      /* insert at the front making things in decending order */
+      struct hw_handle_mapping *new_map = ZALLOC (struct hw_handle_mapping);
+      new_map->next = db->mappings;
+      new_map->ihandle = internal;
+      db->nr_mappings += 1;
+      new_map->external = db->nr_mappings;
+      db->mappings = new_map;
+    }
+}
+
+
+void
+hw_handle_add_phandle (struct hw *hw,
+		       struct hw *internal)
+{
+  struct hw_handle_data *db = hw->handles_of_hw;
+  if (hw_handle_2phandle (hw, internal) != NULL) 
+    {
+      hw_abort (hw, "attempting to add a phandle already in the data base");
+    }
+  else
+    {
+      /* insert at the front making things in decending order */
+      struct hw_handle_mapping *new_map = ZALLOC (struct hw_handle_mapping);
+      new_map->next = db->mappings;
+      new_map->phandle = internal;
+      db->nr_mappings += 1;
+      new_map->external = db->nr_mappings;
+      db->mappings = new_map;
+    }
+}
+
+
+void
+hw_handle_remove_ihandle (struct hw *hw,
+			  struct hw_instance *internal)
+{
+  struct hw_handle_data *db = hw->handles_of_hw;
+  struct hw_handle_mapping **current_map = &db->mappings;
+  while (*current_map != NULL)
+    {
+      if ((*current_map)->ihandle == internal)
+	{
+	  struct hw_handle_mapping *delete = *current_map;
+	  *current_map = delete->next;
+	  zfree (delete);
+	  return;
+	}
+      current_map = &(*current_map)->next;
+    }
+  hw_abort (hw, "attempt to remove nonexistant ihandle");
+}
+
+
+void
+hw_handle_remove_phandle (struct hw *hw,
+			  struct hw *internal)
+{
+  struct hw_handle_data *db = hw->handles_of_hw;
+  struct hw_handle_mapping **current_map = &db->mappings;
+  while (*current_map != NULL)
+    {
+      if ((*current_map)->phandle == internal)
+	{
+	  struct hw_handle_mapping *delete = *current_map;
+	  *current_map = delete->next;
+	  zfree (delete);
+	  return;
+	}
+      current_map = &(*current_map)->next;
+    }
+  hw_abort (hw, "attempt to remove nonexistant phandle");
+}
+
+
diff --git a/sim/common/hw-handles.h b/sim/common/hw-handles.h
new file mode 100644
index 0000000000..087c9d02e7
--- /dev/null
+++ b/sim/common/hw-handles.h
@@ -0,0 +1,63 @@
+/*  This file is part of the program psim.
+
+    Copyright (C) 1994-1995,1997-1998, Andrew Cagney <cagney@highland.com.au>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+ 
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ 
+    */
+
+
+#ifndef HW_HANDLES_H
+#define HW_HANDLES_H
+
+
+/* Export a capability (handle) data base that maps between internal
+   data values and those given to a simulation. */
+
+
+cell_word hw_handle_2ihandle
+(struct hw *db,
+ struct hw_instance *instance);
+
+struct hw_instance *hw_handle_ihandle2
+(struct hw *db,
+ cell_word external);
+
+void hw_handle_add_ihandle
+(struct hw *db,
+ struct hw_instance *instance);
+
+void hw_handle_remove_ihandle
+(struct hw *db,
+ struct hw_instance *instance);
+
+
+cell_word hw_handle_2phandle
+(struct hw *db,
+ struct hw *hw);
+
+struct hw *hw_handle_phandle2
+(struct hw *db,
+ cell_word external);
+
+void hw_handle_add_phandle
+(struct hw *db,
+ struct hw *hw);
+
+void hw_handle_remove_phandle
+(struct hw *db,
+ struct hw *hw);
+
+#endif
diff --git a/sim/common/hw-instances.c b/sim/common/hw-instances.c
new file mode 100644
index 0000000000..31393b141d
--- /dev/null
+++ b/sim/common/hw-instances.c
@@ -0,0 +1,285 @@
+/*  This file is part of the program psim.
+
+    Copyright (C) 1994-1998, Andrew Cagney <cagney@highland.com.au>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+ 
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ 
+    */
+
+
+#include "hw-main.h"
+#include "hw-base.h"
+
+#define ASSERT(X)
+
+struct hw_instance_data {
+  hw_finish_instance_method *to_finish;
+  struct hw_instance *instances;
+};
+
+static hw_finish_instance_method abort_hw_finish_instance;
+
+void
+create_hw_instance_data (struct hw *me)
+{
+  me->instances_of_hw = HW_ZALLOC (me, struct hw_instance_data);
+  set_hw_finish_instance (me, abort_hw_finish_instance);
+}
+
+void
+delete_hw_instance_data (struct hw *me)
+{
+  /* NOP */
+}
+
+
+static void
+abort_hw_finish_instance (struct hw *hw,
+			  struct hw_instance *instance)
+{
+  hw_abort (hw, "no instance finish method");
+}
+
+void
+set_hw_finish_instance (struct hw *me,
+			hw_finish_instance_method *finish)
+{
+  me->instances_of_hw->to_finish = finish;
+}
+
+
+#if 0
+void
+clean_hw_instances (struct hw *me)
+{
+  struct hw_instance **instance = &me->instances;
+  while (*instance != NULL)
+    {
+      struct hw_instance *old_instance = *instance;
+      hw_instance_delete (old_instance);
+      instance = &me->instances;
+    }
+}
+#endif
+
+
+void
+hw_instance_delete (struct hw_instance *instance)
+{
+#if 1
+  hw_abort (hw_instance_hw (instance), "not implemented");
+#else
+  struct hw *me = hw_instance_hw (instance);
+  if (instance->to_instance_delete == NULL)
+    hw_abort (me, "no delete method");
+  instance->method->delete(instance);
+  if (instance->args != NULL)
+    zfree (instance->args);
+  if (instance->path != NULL)
+    zfree (instance->path);
+  if (instance->child == NULL)
+    {
+      /* only remove leaf nodes */
+      struct hw_instance **curr = &me->instances;
+      while (*curr != instance)
+	{
+	  ASSERT (*curr != NULL);
+	  curr = &(*curr)->next;
+	}
+      *curr = instance->next;
+    }
+  else
+    {
+      /* check it isn't in the instance list */
+      struct hw_instance *curr = me->instances;
+      while (curr != NULL)
+	{
+	  ASSERT(curr != instance);
+	  curr = curr->next;
+	}
+      /* unlink the child */
+      ASSERT (instance->child->parent == instance);
+      instance->child->parent = NULL;
+    }
+  cap_remove (me->ihandles, instance);
+  zfree (instance);
+#endif
+}
+
+
+static int
+panic_hw_instance_read (struct hw_instance *instance,
+			void *addr,
+			unsigned_word len)
+{
+  hw_abort (hw_instance_hw (instance), "no read method");
+  return -1;
+}
+
+
+
+static int
+panic_hw_instance_write (struct hw_instance *instance,
+			 const void *addr,
+			 unsigned_word len)
+{
+  hw_abort (hw_instance_hw (instance), "no write method");
+  return -1;
+}
+
+
+static int
+panic_hw_instance_seek (struct hw_instance *instance,
+			unsigned_word pos_hi,
+			unsigned_word pos_lo)
+{
+  hw_abort (hw_instance_hw (instance), "no seek method");
+  return -1;
+}
+
+
+int
+hw_instance_call_method (struct hw_instance *instance,
+			 const char *method_name,
+			 int n_stack_args,
+			 unsigned_cell stack_args[/*n_stack_args*/],	
+			 int n_stack_returns,
+			 unsigned_cell stack_returns[/*n_stack_args*/])
+{
+#if 1
+  hw_abort (hw_instance_hw (instance), "not implemented");
+  return -1;
+#else
+  struct hw *me = instance->owner;
+  const hw_instance_methods *method = instance->method->methods;
+  if (method == NULL)
+    {
+      hw_abort (me, "no methods (want %s)", method_name);
+    }
+  while (method->name != NULL)
+    {
+      if (strcmp(method->name, method_name) == 0)
+	{
+	  return method->method (instance,
+				 n_stack_args, stack_args,
+				 n_stack_returns, stack_returns);
+	}
+      method++;
+    }
+  hw_abort (me, "no %s method", method_name);
+  return 0;
+#endif
+}
+
+
+#define set_hw_instance_read(instance, method)\
+((instance)->to_instance_read = (method))
+
+#define set_hw_instance_write(instance, method)\
+((instance)->to_instance_write = (method))
+
+#define set_hw_instance_seek(instance, method)\
+((instance)->to_instance_seek = (method))
+
+
+#if 0
+static void
+set_hw_instance_finish (struct hw *me,
+			hw_instance_finish_method *method)
+{
+  if (me->instances_of_hw == NULL)
+    me->instances_of_hw = HW_ZALLOC (me, struct hw_instance_data);
+  me->instances_of_hw->to_finish = method;
+}
+#endif
+
+
+struct hw_instance *
+hw_instance_create (struct hw *me,
+		    struct hw_instance *parent,
+		    const char *path,
+		    const char *args)
+{
+  struct hw_instance *instance = ZALLOC (struct hw_instance);
+  /*instance->unit*/
+  /* link this instance into the devices list */
+  instance->hw_of_instance = me;
+  instance->parent_of_instance = NULL;
+  /* link this instance into the front of the devices instance list */
+  instance->sibling_of_instance = me->instances_of_hw->instances;
+  me->instances_of_hw->instances = instance;
+  if (parent != NULL)
+    {
+      ASSERT (parent->child_of_instance == NULL);
+      parent->child_of_instance = instance;
+      instance->parent_of_instance = parent;
+    }
+  instance->args_of_instance = hw_strdup (me, args);
+  instance->path_of_instance = hw_strdup (me, path);
+  set_hw_instance_read (instance, panic_hw_instance_read);
+  set_hw_instance_write (instance, panic_hw_instance_write);
+  set_hw_instance_seek (instance, panic_hw_instance_seek);
+  hw_handle_add_ihandle (me, instance);
+  me->instances_of_hw->to_finish (me, instance);
+  return instance;
+}
+
+
+struct hw_instance *
+hw_instance_interceed (struct hw_instance *parent,
+		       const char *path,
+		       const char *args)
+{
+#if 1
+  return NULL;
+#else
+  struct hw_instance *instance = ZALLOC (struct hw_instance);
+  /*instance->unit*/
+  /* link this instance into the devices list */
+  if (me != NULL)
+    {
+      ASSERT (parent == NULL);
+      instance->hw_of_instance = me;
+      instance->parent_of_instance = NULL;
+      /* link this instance into the front of the devices instance list */
+      instance->sibling_of_instance = me->instances_of_hw->instances;
+      me->instances_of_hw->instances = instance;
+    }
+  if (parent != NULL)
+    {
+      struct hw_instance **previous;
+      ASSERT (parent->child_of_instance == NULL);
+      parent->child_of_instance = instance;
+      instance->owner = parent->owner;
+      instance->parent_of_instance = parent;
+      /* in the devices instance list replace the parent instance with
+	 this one */
+      instance->next = parent->next;
+      /* replace parent with this new node */
+      previous = &instance->owner->instances;
+      while (*previous != parent)
+	{
+	  ASSERT (*previous != NULL);
+	  previous = &(*previous)->next;
+	}
+      *previous = instance;
+    }
+  instance->data = data;
+  instance->args = (args == NULL ? NULL : (char *) strdup(args));
+  instance->path = (path == NULL ? NULL : (char *) strdup(path));
+  cap_add (instance->owner->ihandles, instance);
+  return instance;
+#endif
+}
diff --git a/sim/common/hw-instances.h b/sim/common/hw-instances.h
new file mode 100644
index 0000000000..6d27b11487
--- /dev/null
+++ b/sim/common/hw-instances.h
@@ -0,0 +1,157 @@
+/*  This file is part of the program psim.
+
+    Copyright (C) 1994-1998, Andrew Cagney <cagney@highland.com.au>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+ 
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ 
+    */
+
+
+#ifndef HW_INSTANCES_H
+#define HW_INSTANCES_H
+
+/* Instances:
+
+   As with IEEE1275, a device can be opened, creating an instance.
+   Instances provide more abstract interfaces to the underlying
+   hardware.  For example, the instance methods for a disk may include
+   code that is able to interpret file systems found on disks.  Such
+   methods would there for allow the manipulation of files on the
+   disks file system.  The operations would be implemented using the
+   basic block I/O model provided by the disk.
+
+   This model includes methods that faciliate the creation of device
+   instance and (should a given device support it) standard operations
+   on those instances.
+
+   */
+
+
+struct hw_instance;
+
+
+typedef void (hw_finish_instance_method)
+     (struct hw *hw,
+      struct hw_instance *);
+
+extern void set_hw_finish_instance
+(struct hw *hw,
+ hw_finish_instance_method *method);
+
+
+/* construct an instance of the hardware */
+
+struct hw_instance *hw_instance_create
+(struct hw *hw,
+ struct hw_instance *parent,
+ const char *path,
+ const char *args);
+
+struct hw_instance *hw_instance_interceed
+(struct hw_instance *parent,
+ const char *path,
+ const char *args);
+
+void hw_instance_delete
+(struct hw_instance *instance);
+
+
+/* methods applied to an instance of the hw */
+
+typedef int (hw_instance_read_method)
+     (struct hw_instance *instance,
+      void *addr,
+      unsigned_cell len);
+
+#define hw_instance_read(instance, addr, len) \
+((instance)->to_instance_read ((instance), (addr), (len)))
+
+#define set_hw_instance_read(instance, method) \
+((instance)->to_instance_read = (method))
+
+
+typedef int (hw_instance_write_method)
+     (struct hw_instance *instance,
+      const void *addr,
+      unsigned_cell len);
+
+#define hw_instance_write(instance, addr, len) \
+((instance)->to_instance_write ((instance), (addr), (len)))
+
+#define set_hw_instance_write(instance, method) \
+((instance)->to_instance_write = (method))
+
+
+typedef int (hw_instance_seek_method)
+     (struct hw_instance *instance,
+      unsigned_cell pos_hi,
+      unsigned_cell pos_lo);
+
+#define hw_instance_seek(instance, pos_hi, pos_lo) \
+((instance)->to_instance_seek ((instance), (pos_hi), (pos_lo)));
+
+#define set_hw_instance_seek(instance, method) \
+((instance)->to_instance_seek = (method))
+
+
+int hw_instance_call_method
+(struct hw_instance *instance,
+ const char *method,
+ int n_stack_args,
+ unsigned_cell stack_args[/*n_stack_args + 1(NULL)*/],
+ int n_stack_returns,
+ unsigned_cell stack_returns[/*n_stack_returns + 1(NULL)*/]);
+
+
+
+/* the definition of the instance */
+
+#define hw_instance_hw(instance) ((instance)->hw_of_instance + 0)
+
+#define hw_instance_path(instance) ((instance)->path_of_instance + 0)
+
+#define hw_instance_args(instance) ((instance)->args_of_instance)
+
+#define hw_instance_data(instance) ((instance)->data_of_instance)
+
+#define hw_instance_system(instance) (hw_system (hw_instance_hw (instance)))
+
+
+
+/* Finally an instance of a hardware device - keep your grubby little
+   mits off of these internals! :-) */
+
+struct hw_instance {
+
+  void *data_of_instance;
+  char *args_of_instance;
+  char *path_of_instance;
+
+  /* the device that owns the instance */
+  struct hw *hw_of_instance;
+  struct hw_instance *sibling_of_instance;
+
+  /* interposed instance */
+  struct hw_instance *parent_of_instance;
+  struct hw_instance *child_of_instance;
+
+  /* methods */
+  hw_instance_read_method *to_instance_read;
+  hw_instance_write_method *to_instance_write;
+  hw_instance_seek_method *to_instance_seek;
+
+};
+
+#endif