diff --git a/src/mame/drivers/astrof.c b/src/mame/drivers/astrof.c
index bcbdc17698c..b139f39f613 100644
--- a/src/mame/drivers/astrof.c
+++ b/src/mame/drivers/astrof.c
@@ -40,9 +40,19 @@
           I have played one that stoped between waves to show the next enemy
 
     Known issues/to-do's:
-        * Is Astro Fighter supposed to have a blue background???
         * Analog sound in all games
 
+    About Colours:
+        * It was fairly common to have wiremods on these PCBs to change the
+          background colours, this is why you see Astro Fighter and Tomahawk
+          games with both Blue and Black backgrounds.  By default MAME
+          emulates an unmodified PCB, you can enable the hacks in the DRIVER
+          CONFIGURATION menu.
+
+          Versions of Tomahawk using the Astro Fighter PROM have been seen,
+          see notes in ROM loading.
+
+
 ****************************************************************************/
 
 
@@ -234,10 +244,36 @@ static void tomahawk_get_pens( running_machine *machine, pen_t *pens )
 {
 	offs_t i;
 	UINT8 *prom = memory_region(machine, "proms");
+	UINT8 config = input_port_read_safe(machine, "FAKE", 0x00);
 
 	for (i = 0; i < TOMAHAWK_NUM_PENS; i++)
 	{
-		UINT8 data = prom[i];
+		UINT8 data; 
+		UINT8 pen;
+ 
+		/* a common wire hack to the pcb causes the prom halves to be inverted */
+		/* this results in e.g. astrof background being black */
+		switch (config)
+		{
+		case 0:
+			/* normal PROM access */
+			pen = i;
+			break;
+		case 1:
+			/* invert PROM acess */
+			pen = i ^ 0x10;
+			break;
+		case 2:
+			/* force low */
+			pen = i & 0x0f;
+			break;
+		default:
+			/* force high */
+			pen = i | 0x10;
+			break;
+		}
+
+		data = prom[pen];
 
 		pens[i] = make_pen(machine, data);
 	}
@@ -842,6 +878,8 @@ INPUT_PORTS_END
 
 
 static INPUT_PORTS_START( tomahawk )
+	PORT_INCLUDE( astrof_common )
+
 	PORT_START("IN")
 	PORT_BIT( 0x1f, IP_ACTIVE_HIGH, IPT_SPECIAL ) PORT_CUSTOM(tomahawk_controls_r, NULL)
 	PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_START1 )
@@ -1231,6 +1269,11 @@ ROM_START( tomahawk )
 
 	ROM_REGION( 0x0020, "proms", 0 )
 	ROM_LOAD( "t777.clr",     0x0000, 0x0020, CRC(d6a528fd) SHA1(5fc08252a2d7c5405f601efbfb7d84bec328d733) )
+	
+	// versions of this have also been seen using the standard Astro Fighter PROM, giving a blue submarine
+	// in blue water, with pink / yellow borders.  I think these are just unofficial conversions of Astro
+	// Fighter without the PROM properly replaced tho.
+	//ROM_LOAD( "astrf.clr",    0x0000, 0x0020, CRC(61329fd1) SHA1(15782d8757d4dda5a8b97815e94c90218f0e08dd) )
 ROM_END