diff --git a/src/mame/drivers/segas16b.cpp b/src/mame/drivers/segas16b.cpp
index 5e7f0a47a1f..5aafd22cce5 100644
--- a/src/mame/drivers/segas16b.cpp
+++ b/src/mame/drivers/segas16b.cpp
@@ -3905,28 +3905,27 @@ static INPUT_PORTS_START( dfjail )
 	PORT_SERVICE_DIPLOC( 0x80, 0x80, "SW1:8" )
 
 	PORT_MODIFY("DSW2")
-	PORT_DIPNAME( 0x01, 0x01, DEF_STR( Unknown ) ) PORT_DIPLOCATION("SW2:1")
-	PORT_DIPSETTING(    0x01, DEF_STR( Off ) )
-	PORT_DIPSETTING(    0x00, DEF_STR( On ) )
-	PORT_DIPNAME( 0x02, 0x02, DEF_STR( Unknown ) ) PORT_DIPLOCATION("SW2:2")
-	PORT_DIPSETTING(    0x02, DEF_STR( Off ) )
-	PORT_DIPSETTING(    0x00, DEF_STR( On ) )
+	PORT_DIPNAME( 0x03, 0x02, DEF_STR( Difficulty ) ) PORT_DIPLOCATION("SW2:1,2")
+	PORT_DIPSETTING(    0x03, DEF_STR( Easy ) )
+	PORT_DIPSETTING(    0x02, DEF_STR( Normal ) )
+	PORT_DIPSETTING(    0x01, DEF_STR( Hard ) )
+	PORT_DIPSETTING(    0x00, DEF_STR( Hardest ) )
 	PORT_DIPNAME( 0x04, 0x00, DEF_STR( Demo_Sounds ) ) PORT_DIPLOCATION("SW2:3") // it's actually BGM in attract mode
 	PORT_DIPSETTING(    0x04, DEF_STR( Off ) )
 	PORT_DIPSETTING(    0x00, DEF_STR( On ) )
 	PORT_DIPNAME( 0x08, 0x08, DEF_STR( Flip_Screen ) ) PORT_DIPLOCATION("SW2:4")
 	PORT_DIPSETTING(    0x08, DEF_STR( Off ) )
 	PORT_DIPSETTING(    0x00, DEF_STR( On ) )
-	PORT_DIPNAME( 0x10, 0x10, DEF_STR( Unknown ) ) PORT_DIPLOCATION("SW2:5")
+	PORT_DIPNAME( 0x10, 0x10, DEF_STR( Unused ) ) PORT_DIPLOCATION("SW2:5") // from here on not used according to the manual
 	PORT_DIPSETTING(    0x10, DEF_STR( Off ) )
 	PORT_DIPSETTING(    0x00, DEF_STR( On ) )
-	PORT_DIPNAME( 0x20, 0x20, DEF_STR( Unknown ) ) PORT_DIPLOCATION("SW2:6")
+	PORT_DIPNAME( 0x20, 0x20, DEF_STR( Unused ) ) PORT_DIPLOCATION("SW2:6")
 	PORT_DIPSETTING(    0x20, DEF_STR( Off ) )
 	PORT_DIPSETTING(    0x00, DEF_STR( On ) )
-	PORT_DIPNAME( 0x40, 0x40, DEF_STR( Unknown ) ) PORT_DIPLOCATION("SW2:7")
+	PORT_DIPNAME( 0x40, 0x40, DEF_STR( Unused ) ) PORT_DIPLOCATION("SW2:7")
 	PORT_DIPSETTING(    0x40, DEF_STR( Off ) )
 	PORT_DIPSETTING(    0x00, DEF_STR( On ) )
-	PORT_DIPNAME( 0x80, 0x80, DEF_STR( Unknown ) ) PORT_DIPLOCATION("SW2:8")
+	PORT_DIPNAME( 0x80, 0x80, DEF_STR( Unused ) ) PORT_DIPLOCATION("SW2:8")
 	PORT_DIPSETTING(    0x80, DEF_STR( Off ) )
 	PORT_DIPSETTING(    0x00, DEF_STR( On ) )
 INPUT_PORTS_END
@@ -10001,7 +10000,7 @@ GAME( 1990, atomicp,    0,        atomicp,               atomicp,  segas16b_stat
 GAME( 1990, snapper,    0,        atomicp,               snapper,  segas16b_state, init_snapper,            ROT0,   "Philko", "Snapper (Korea)", 0) // korean clone board..
 // board marked 'System 4' and has Philko custom chip - various hw changes (4bpp tiles for example)
 GAME( 1991, lockonph,   0,        lockonph,              lockonph, segas16b_state, init_lockonph,           ROT0,   "Philko", "Lock On (Philko)", MACHINE_IMPERFECT_SOUND ) // Copyright not shown in game, but has 'PHILKO' in the startup warning and tiles / PCB.  1991 is the name entry for the lowest high score.  Clipping issues on left edge in attract look like original game bugs.
-GAME( 199?, dfjail,   0,          dfjail,                dfjail,   dfjail_state,   init_generic_korean,     ROT0,   "Philko", "The Destroyer From Jail (Korea)", MACHINE_IMPERFECT_SOUND | MACHINE_NO_COCKTAIL ) // dips, check sound, not extensively tested
+GAME( 199?, dfjail,   0,          dfjail,                dfjail,   dfjail_state,   init_generic_korean,     ROT0,   "Philko", "The Destroyer From Jail (Korea)", MACHINE_NO_COCKTAIL )
 
 // decrypted bootleg / 'suicide repair' sets