diff --git a/src/mame/drivers/merits.cpp b/src/mame/drivers/merits.cpp
index e36d29e17a6..71c32dec4a6 100644
--- a/src/mame/drivers/merits.cpp
+++ b/src/mame/drivers/merits.cpp
@@ -5,7 +5,7 @@
     Skeleton driver for Merit Scorpion darts machines
 
     Hardware overview:
-    Main CPU: Dallas DS80C3202-UM or compatible
+    Main CPU: Dallas DS80C3202-UM or compatible (80C31 on older models)
     Sound: DAC?
     NVRAM: Dallas DS1220Y-120 or compatible
     Other: Dallas DS1232 MicroMonitor
@@ -21,6 +21,7 @@
 #include "sound/dac.h"
 #include "speaker.h"
 
+namespace {
 
 class merits_state : public driver_device
 {
@@ -32,6 +33,7 @@ public:
 	}
 
 	void scrpiond(machine_config &config);
+	void scrpiondold(machine_config &config);
 
 private:
 	void mem_map(address_map &map);
@@ -58,6 +60,25 @@ void merits_state::io_map(address_map &map)
 }
 
 static INPUT_PORTS_START(scrpiond)
+	PORT_START("DSW1")
+	PORT_DIPUNKNOWN_DIPLOC(0x01, 0x01, "SW1:1")
+	PORT_DIPUNKNOWN_DIPLOC(0x02, 0x02, "SW1:2")
+	PORT_DIPUNKNOWN_DIPLOC(0x04, 0x04, "SW1:3")
+	PORT_DIPUNKNOWN_DIPLOC(0x08, 0x08, "SW1:4")
+	PORT_DIPUNKNOWN_DIPLOC(0x10, 0x10, "SW1:5")
+	PORT_DIPUNKNOWN_DIPLOC(0x20, 0x20, "SW1:6")
+	PORT_DIPUNKNOWN_DIPLOC(0x40, 0x40, "SW1:7")
+	PORT_DIPUNKNOWN_DIPLOC(0x80, 0x80, "SW1:8")
+
+	PORT_START("DSW2")
+	PORT_DIPUNKNOWN_DIPLOC(0x01, 0x01, "SW1:1")
+	PORT_DIPUNKNOWN_DIPLOC(0x02, 0x02, "SW1:2")
+	PORT_DIPUNKNOWN_DIPLOC(0x04, 0x04, "SW1:3")
+	PORT_DIPUNKNOWN_DIPLOC(0x08, 0x08, "SW1:4")
+	PORT_DIPUNKNOWN_DIPLOC(0x10, 0x10, "SW1:5")
+	PORT_DIPUNKNOWN_DIPLOC(0x20, 0x20, "SW1:6")
+	PORT_DIPUNKNOWN_DIPLOC(0x40, 0x40, "SW1:7")
+	PORT_DIPUNKNOWN_DIPLOC(0x80, 0x80, "SW1:8")
 INPUT_PORTS_END
 
 void merits_state::scrpiond(machine_config &config)
@@ -69,6 +90,15 @@ void merits_state::scrpiond(machine_config &config)
 	NVRAM(config, "nvram", nvram_device::DEFAULT_ALL_0); // DS1220Y
 }
 
+void merits_state::scrpiondold(machine_config &config)
+{
+	I80C31(config, m_maincpu, 12_MHz_XTAL);
+	m_maincpu->set_addrmap(AS_PROGRAM, &merits_state::mem_map);
+	m_maincpu->set_addrmap(AS_IO, &merits_state::io_map);
+
+	NVRAM(config, "nvram", nvram_device::DEFAULT_ALL_0); // DS1220Y
+}
+
 ROM_START(scrpiond)
 	ROM_REGION(0x10000, "maincpu", 0)
 	ROM_LOAD( "27c512.u7", 0x00000, 0x10000, CRC(06cdf965) SHA1(4cdac131063fc0dd954eaaee2ae40d5731f83469) )
@@ -79,6 +109,15 @@ ROM_START(scrpionda)
 	ROM_LOAD( "4978-22_u7-r5_c1997_mii.u7", 0x00000, 0x10000, CRC(e647a17e) SHA1(4a7b9e2af3656a1b6f4ffd8c17b68eec5c534776) )
 ROM_END
 
+// Old PCB model, i80C31 instead of 80C32. The DS1204U-3 socket is still unpopulated. Other PCB components stays the same.
+ROM_START(scrpiondb)
+	ROM_REGION(0x10000, "maincpu", 0)
+	ROM_LOAD( "4778-02_u7-r02_c1994_mii.u7", 0x00000, 0x10000, CRC(57a5083d) SHA1(edb94dbb9e040e960c45406b082ede133574351a) )
+ROM_END
 
-GAME(1999, scrpiond,         0, scrpiond, scrpiond, merits_state, empty_init, ROT0, "Merit", "Scorpion (Jun 15, 1999)", MACHINE_IS_SKELETON_MECHANICAL)
-GAME(1997, scrpionda, scrpiond, scrpiond, scrpiond, merits_state, empty_init, ROT0, "Merit", "Scorpion (Oct 01, 1997)", MACHINE_IS_SKELETON_MECHANICAL)
+} // Anonymous namespace
+
+//   YEAR  NAME       PARENT    COMPAT       MACHINE   INPUT         CLASS       INIT  COMPANY  FULLNAME                   FLAGS
+GAME(1999, scrpiond,         0, scrpiond,    scrpiond, merits_state, empty_init, ROT0, "Merit", "Scorpion (Jun 15, 1999)", MACHINE_IS_SKELETON_MECHANICAL)
+GAME(1997, scrpionda, scrpiond, scrpiond,    scrpiond, merits_state, empty_init, ROT0, "Merit", "Scorpion (Oct 01, 1997)", MACHINE_IS_SKELETON_MECHANICAL)
+GAME(1993, scrpiondb, scrpiond, scrpiondold, scrpiond, merits_state, empty_init, ROT0, "Merit", "Scorpion (Dec 24, 1993)", MACHINE_IS_SKELETON_MECHANICAL)
diff --git a/src/mame/mame.lst b/src/mame/mame.lst
index f730ada3627..d901110484e 100644
--- a/src/mame/mame.lst
+++ b/src/mame/mame.lst
@@ -22872,8 +22872,9 @@ realbroda                       // (c) 1995 Merit
 spitboss                        // (c) 1988 Merit
 
 @source:merits.cpp
-scrpiond                        //
-scrpionda                       //
+scrpiond                        // (c) 1999 Merit Industries, Inc.
+scrpionda                       // (c) 1997 Merit Industries, Inc.
+scrpiondb                       // (c) 1993 Merit Industries, Inc.
 
 @source:meritsdx.cpp
 scrpndx                        //