gameplan: possible fix for piratetr lockup

src/mame/gameplan/gameplan.cpp

@@ -64,13 +64,21 @@ Address          Dir Data     Name      Description
   Megattack
   Pot Of Gold (Leprechaun)
 
+- Leprechaun and Pirate Treasure were made for the Moppet Video arcade series
+  (Enter-Tech arcade cabs aimed at younger children). That's why the games are
+  so easy.
+
 
 TODO:
 - The board has, instead of a watchdog, a timed reset that has to be disabled
   on startup. The disable line is tied to CA2 of VIA2, but I don't see writes
   to that pin in the log. Missing support in machine/6522via.cpp?
 - Investigate and document the 8910 dip switches
 - Fix the input ports of Kaos
+- Some of the games do unmapped reads all over the place, probably just bad
+  programming. One of these is piratetr, and it will lock up eventually when
+  reading from VIA1. It's possible to fix with a simple wire mod/pcb cut trace,
+  like done with piratetr_main_map. Let's assume they did something like that.
 
 ****************************************************************************/
 
@@ -349,6 +357,12 @@ void gameplan_state::gameplan_main_map(address_map &map)
 	map(0x8000, 0xffff).rom();
 }
 
+void gameplan_state::piratetr_main_map(address_map &map)
+{
+	gameplan_main_map(map);
+	map(0x2010, 0x201f).mirror(0x07e0).unmaprw(); // A4, see TODO
+}
+
 
 
 /*************************************
@@ -1174,6 +1188,12 @@ void gameplan_state::leprechn(machine_config &config)
 	m_via[0]->writepb_handler().set(FUNC(gameplan_state::video_command_w)).rshift(3);
 }
 
+void gameplan_state::piratetr(machine_config &config)
+{
+	leprechn(config);
+	m_maincpu->set_addrmap(AS_PROGRAM, &gameplan_state::piratetr_main_map);
+}
+
 
 
 /*************************************
@@ -1336,4 +1356,4 @@ GAME( 1981, kaos,      0,        gameplan, kaos,      gameplan_state, empty_init
 GAME( 1982, leprechn,  0,        leprechn, leprechn,  gameplan_state, empty_init, ROT0,   "Pacific Polytechnical Corp.",                           "Leprechaun (set 1)", MACHINE_SUPPORTS_SAVE )
 GAME( 1982, leprechna, leprechn, leprechn, leprechna, gameplan_state, empty_init, ROT0,   "Pacific Polytechnical Corp. (Tong Electronic license)", "Leprechaun (set 2)", MACHINE_SUPPORTS_SAVE )
 GAME( 1982, potogold,  leprechn, leprechn, leprechn,  gameplan_state, empty_init, ROT0,   "Pacific Polytechnical Corp. (Game Plan license)",       "Pot of Gold",        MACHINE_SUPPORTS_SAVE )
-GAME( 1982, piratetr,  0,        leprechn, piratetr,  gameplan_state, empty_init, ROT0,   "Pacific Polytechnical Corp. (Tong Electronic license)", "Pirate Treasure",    MACHINE_SUPPORTS_SAVE )
+GAME( 1982, piratetr,  0,        piratetr, piratetr,  gameplan_state, empty_init, ROT0,   "Pacific Polytechnical Corp. (Tong Electronic license)", "Pirate Treasure",    MACHINE_SUPPORTS_SAVE )

src/mame/gameplan/gameplan.h

@@ -35,6 +35,7 @@ class gameplan_state : public driver_device
 	void gameplan(machine_config &config);
 	void gameplan_video(machine_config &config);
 	void leprechn(machine_config &config);
+	void piratetr(machine_config &config);
 
 protected:
 	virtual void machine_start() override;
@@ -91,4 +92,5 @@ class gameplan_state : public driver_device
 	void gameplan_main_map(address_map &map);
 	void gameplan_audio_map(address_map &map);
 	void leprechn_audio_map(address_map &map);
+	void piratetr_main_map(address_map &map);
 };