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Diffstat (limited to 'src/mame/drivers/alinvade.c')
-rw-r--r--src/mame/drivers/alinvade.c42
1 files changed, 29 insertions, 13 deletions
diff --git a/src/mame/drivers/alinvade.c b/src/mame/drivers/alinvade.c
index 542f472cff5..2a47f44a7b6 100644
--- a/src/mame/drivers/alinvade.c
+++ b/src/mame/drivers/alinvade.c
@@ -4,7 +4,11 @@
does it use any off-the shelf chips in addition to the 6502?
-
+ TODO:
+ - 16 bytes are protected in the c*** range. I'm guessing they used a PROM to protect a
+ simple sub-routine because just after that the program has a left-over located at 0xe000-0xe00f (yup, NOPs + a RTS)
+ It's unknown at current stage what it really protects tho ...
+
*/
#include "emu.h"
@@ -20,6 +24,8 @@ public:
{ }
UINT8 irqmask;
+ UINT8 irqff;
+ DECLARE_READ8_MEMBER(irqmask_r);
DECLARE_WRITE8_MEMBER(irqmask_w);
INTERRUPT_GEN_MEMBER(vblank_irq);
required_device<cpu_device> m_maincpu;
@@ -31,9 +37,18 @@ public:
UINT32 screen_update_alinvade(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect);
};
+READ8_MEMBER(alinvade_state::irqmask_r)
+{
+ return 0; // TODO: might be anything
+}
+
+
WRITE8_MEMBER(alinvade_state::irqmask_w)
{
- irqmask = data;
+ if((!(irqff & 1)) && (data & 1)) // f/f, active high? If the above actually returns 0xff this could be active low ...
+ irqmask^= 1;
+
+ irqff = data;
}
static ADDRESS_MAP_START( alinvade_map, AS_PROGRAM, 8, alinvade_state )
@@ -49,11 +64,10 @@ static ADDRESS_MAP_START( alinvade_map, AS_PROGRAM, 8, alinvade_state )
AM_RANGE(0x8003, 0x8003) AM_READ_PORT("IN3")
AM_RANGE(0x8004, 0x8004) AM_READ_PORT("IN4")
AM_RANGE(0xa000, 0xa000) AM_WRITENOP //??
- AM_RANGE(0xc400, 0xc7ff) AM_ROM
- AM_RANGE(0xc800, 0xcbff) AM_ROM
+ AM_RANGE(0xc000, 0xc00f) AM_MIRROR(0xff0) AM_ROM AM_REGION("proms",0)
AM_RANGE(0xe000, 0xe3ff) AM_ROM
- AM_RANGE(0xe400, 0xe400) AM_WRITE(irqmask_w) //??
- AM_RANGE(0xe800, 0xe800) AM_READNOP AM_WRITENOP //??
+ AM_RANGE(0xe400, 0xe400) AM_WRITENOP //??
+ AM_RANGE(0xe800, 0xe800) AM_READWRITE(irqmask_r,irqmask_w) //??
AM_RANGE(0xec00, 0xffff) AM_ROM
ADDRESS_MAP_END
@@ -102,6 +116,7 @@ void alinvade_state::machine_start()
void alinvade_state::machine_reset()
{
+ irqmask = 1;
}
UINT32 alinvade_state::screen_update_alinvade(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect)
@@ -136,9 +151,6 @@ INTERRUPT_GEN_MEMBER(alinvade_state::vblank_irq)
m_maincpu->set_input_line(0,HOLD_LINE);
}
-
-
-
static MACHINE_CONFIG_START( alinvade, alinvade_state )
/* basic machine hardware */
@@ -154,6 +166,8 @@ static MACHINE_CONFIG_START( alinvade, alinvade_state )
MCFG_SCREEN_VISIBLE_AREA(0, 128-1, 0, 128-1)
MCFG_SCREEN_UPDATE_DRIVER(alinvade_state, screen_update_alinvade)
+ // TODO: MCFG_DEFAULT_LAYOUT for square pixels
+
/* sound hardware */
MCFG_SPEAKER_STANDARD_MONO("mono")
MACHINE_CONFIG_END
@@ -162,16 +176,18 @@ MACHINE_CONFIG_END
ROM_START( alinvade )
ROM_REGION( 0x10000, "maincpu", 0 ) // todo, check mapping
-
- ROM_FILL( 0xc400, 0x800, 0x60 ) // rts for whole area, interrupt code jumps to various addresses here
-
ROM_LOAD( "alien28.708", 0xe000, 0x0400, CRC(de376295) SHA1(e8eddbb1be1f8661c6b5b39c0d78a65bded65db2) )
ROM_LOAD( "alien29.708", 0xec00, 0x0400, CRC(20212977) SHA1(9d24a6b403d968267079fa6241545bd5a01afebb) )
ROM_LOAD( "alien30.708", 0xf000, 0x0400, CRC(734b691c) SHA1(9e562159061eecf4b1dee4ea0ee4752c901a54aa) )
ROM_LOAD( "alien31.708", 0xf400, 0x0400, CRC(5a70535c) SHA1(2827e7d4bffca78bd035da04481e1e972ee2da39) )
ROM_LOAD( "alien32.708", 0xf800, 0x0400, CRC(332dd234) SHA1(9974668344a2a351868a9e7757d1c3a497dc5621) )
ROM_LOAD( "alien33.708", 0xfc00, 0x0400, CRC(e0d57fc7) SHA1(7b8ddcb4a86811592d2d0bbc61b2f19e5caa9ccc) )
+
+ ROM_REGION( 0x20, "proms", 0 )
+ ROM_LOAD( "prom", 0, 0x20, NO_DUMP )
+ ROM_FILL( 0x00, 0x0f, 0xea )
+ ROM_FILL( 0x0f, 0x01, 0x60 ) // rts for whole area, interrupt code jumps to various addresses here, check note on top.
ROM_END
-GAME( 198?, alinvade, 0, alinvade, alinvade, driver_device, 0, ROT90, "Forbes?", "Alien Invaders", GAME_NOT_WORKING )
+GAME( 198?, alinvade, 0, alinvade, alinvade, driver_device, 0, ROT90, "Forbes?", "Alien Invaders", GAME_UNEMULATED_PROTECTION )