diff --git a/src/gc.c b/src/gc.c
index 102b9f15..76f2965e 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -123,15 +123,16 @@ gc_init ()                      /*:((internal)) */
     MAX_STRING = atoi (p);
 
   long arena_bytes = (ARENA_SIZE + JAM_SIZE) * sizeof (struct scm);
-#if! POINTER_CELLS
-  long alloc_bytes = arena_bytes + (STACK_SIZE * sizeof (SCM));
+#if !POINTER_CELLS || GC_NOFLIP
+  long alloc_bytes = arena_bytes + (STACK_SIZE * sizeof (struct scm));
 #else
   long alloc_bytes = (arena_bytes * 2) + (STACK_SIZE * sizeof (struct scm*));
 #endif
+
   g_arena = malloc (alloc_bytes);
   g_cells = g_arena;
 
-#if! POINTER_CELLS
+#if !POINTER_CELLS || GC_NOFLIP
   g_stack_array = g_arena + arena_bytes;
 #else
   g_stack_array = g_arena + (arena_bytes * 2);
@@ -346,7 +347,17 @@ gc_init_news ()                 /*:((internal)) */
   g_news = g_cells + g_free;
   SCM ncell_arena = cell_arena;
 #else
+
+#if GC_NOFLIP
   g_news = g_free;
+#else
+  char* p = g_cells - M2_CELL_SIZE;
+  if (p == g_arena)
+    g_news = g_free;
+  else
+    g_news = g_arena;
+#endif
+
   SCM ncell_arena = g_news;
 #endif
 
@@ -413,14 +424,114 @@ void *p = realloc (g_cells - M2_CELL_SIZE, realloc_bytes);
   return 0;
 }
 
+void
+gc_cellcpy (struct scm *dest, struct scm *src, size_t n)
+{
+  void *p = src;
+  void *q = dest;
+  long dist = p - q;
+  while (n != 0)
+    {
+      long t = src->type;
+      long a = src->car;
+      long d = src->cdr;
+      dest->type = t;
+      if (t == TBROKEN_HEART)
+        {
+          dest->type = 0;
+          a = 0;
+          d = 0;
+#if 0
+          assert_msg (0, "gc_cellcpy: broken heart");
+#endif
+        }
+      if (t == TMACRO
+          || t == TPAIR
+          || t == TREF
+          || t == TVARIABLE)
+        dest->car = a - dist;
+      else
+        dest->car = a;
+      if ((t == TBYTES
+           || t == TCLOSURE
+           || t == TCONTINUATION
+           || t == TKEYWORD
+           || t == TMACRO
+           || t == TPAIR
+           || t == TPORT
+           || t == TSPECIAL
+           || t == TSTRING
+           || t == TSTRUCT
+           || t == TSYMBOL
+           || t == TVALUES
+           || t == TVECTOR)
+          && src->cdr)   // allow for 0 terminated list of symbols
+        dest->cdr = d - dist;
+      else
+        dest->cdr = d;
+      if (t == TBYTES)
+        {
+#if GC_TEST
+          eputs ("copying bytes[");
+          eputs (ntoab (&src->cdr, 16, 0));
+          eputs (", ");
+          eputs (ntoab (a, 10, 0));
+          eputs ("]: ");
+          eputs (&src->cdr);
+          eputs ("\n to [");
+          eputs (ntoab (&dest->cdr, 16, 0));
+#endif
+          memcpy (&dest->cdr, &src->cdr, a);
+#if GC_TEST
+          eputs ("]: ");
+          eputs (&dest->cdr);
+          eputs ("\n");
+#endif
+          n = n - a;
+          int c = bytes_cells (a) * M2_CELL_SIZE;
+          dest = dest + c;
+          src = src + c;
+        }
+      else
+        {
+          n = n - 1;
+          dest = dest + M2_CELL_SIZE;
+          src = src + M2_CELL_SIZE;
+        }
+    }
+}
+
 void
 gc_flip ()
 {
 #if POINTER_CELLS
+  if (g_free - g_news > JAM_SIZE)
+    JAM_SIZE = (g_free - g_news) + ((g_free - g_news) / 2);
+
+#if GC_NOFLIP
+  cell_arena = g_cells - M2_CELL_SIZE; /* FIXME? */
+  gc_cellcpy (g_cells, g_news, (g_free - g_news) / M2_CELL_SIZE);
+
+  void *p = g_news;
+  void *q = g_cells;
+  long dist = p - q;
+
+  g_free = (void*)g_free - dist;
+#if !GC_TEST
+  g_symbols = (void*)g_symbols - dist;
+  g_symbol_max = (void*)g_symbol_max - dist;
+  g_macros = (void*)g_macros - dist;
+  g_ports = (void*)g_ports - dist;
+  M0 = (void*)M0 - dist;
+#endif
+
+#else
+
   g_cells = g_news;
   cell_arena = g_news - M2_CELL_SIZE;
   cell_zero = cell_arena + M2_CELL_SIZE;
   cell_nil = cell_zero + M2_CELL_SIZE;
+#endif
 #endif
 
   if (g_debug > 2)
@@ -510,7 +621,14 @@ gc_loop (SCM scan)              /*:((internal)) */
     {
       long t = NTYPE (scan);
       if (t == TBROKEN_HEART)
-        assert_msg (0, "broken heart");
+        {
+          NTYPE (scan) = 0;
+          NCAR (scan) = 0;
+          NCDR (scan) = 0;
+#if 0
+          assert_msg (0, "gc_loop: broken heart");
+#endif
+        }
       if (t == TMACRO
           || t == TPAIR
           || t == TREF
@@ -603,9 +721,14 @@ gc_ ()
     gc_copy (s);
 
 #if POINTER_CELLS
+  cell_arena = g_news - M2_CELL_SIZE; /* for debugging */
+
 #if GC_TEST
   cell_nil = save_gfree;
+  cell_zero = cell_nil - M2_CELL_SIZE;
+  g_symbol_max = g_free;
 #else
+  cell_nil = save_gfree;
   long save_gsymbols = g_symbols;
   cell_nil = save_gfree;
   g_symbols = 0;
@@ -616,13 +739,16 @@ gc_ ()
 #endif
 #endif
 
+#if !GC_TEST
   g_symbols = gc_copy (g_symbols);
   g_macros = gc_copy (g_macros);
   g_ports = gc_copy (g_ports);
   M0 = gc_copy (M0);
+
   long i;
   for (i = g_stack; i < STACK_SIZE; i = i + 1)
     copy_stack (i, gc_copy (g_stack_array[i]));
+#endif
 
   gc_loop (cell_nil);
 }