// license:BSD-3-Clause // copyright-holders:David Haywood, Mariusz Wojcieszek /* tiny bartop b&w Space Invaders type game with colour overlay Driver by David Haywood and Mariusz Wojcieszek TODO: - 16 bytes are protected in the c*** range. I'm guessing they used a PROM to protect a simple sub-routine because: * It attempts to jsr from RAM to that area with a 0x10 byte offset (i.e. ROM copies a code snippet to RAM; when it executes it code executes jsr 0xc400 then self-modifies it to 0xc410, rinse and repeat ... up to 0xc7f0 and rolls back); * After that the program has an amusing left-over located at 0xe000-0xe00f (yup, NOPs + a RTS), with the exact same number of times as above; It's unknown at current stage what it really protects tho, game seems working for all I can see ... -AS - Sound is entirely guesswork. */ #include "emu.h" #include "cpu/m6502/m6502.h" #include "sound/discrete.h" #include "screen.h" #include "speaker.h" #include "alinvade.lh" class alinvade_state : public driver_device { public: alinvade_state(const machine_config &mconfig, device_type type, const char *tag) : driver_device(mconfig, type, tag) , m_maincpu(*this, "maincpu") , m_videoram(*this, "videoram") , m_discrete(*this, "discrete") { } void alinvade(machine_config &config); private: uint8_t irqmask_r(); void irqmask_w(uint8_t data); void sound_w(uint8_t data); void sounden_w(uint8_t data); void vblank_irq(int state); uint32_t screen_update(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect); void alinvade_map(address_map &map); uint8_t m_irqmask = 0; uint8_t m_irqff = 0; virtual void machine_start() override; virtual void machine_reset() override; required_device m_maincpu; required_shared_ptr m_videoram; required_device m_discrete; }; static const discrete_dac_r1_ladder alinvade_music_dac = {3, {0, RES_K(47), RES_K(12)}, 0, 0, 0, CAP_U(0.01)}; #define ALINVADE_MUSIC_CLK (75000) DISCRETE_SOUND_START(alinvade_discrete) DISCRETE_INPUT_DATA (NODE_01) DISCRETE_NOTE(NODE_20, 1, ALINVADE_MUSIC_CLK, NODE_01, 255, 5, DISC_CLK_IS_FREQ) // Convert count to 7492 output DISCRETE_TRANSFORM2(NODE_21, NODE_20, 2, "01>0+") DISCRETE_DAC_R1(NODE_22, NODE_21, DEFAULT_TTL_V_LOGIC_1, &alinvade_music_dac) DISCRETE_CRFILTER(NODE_80, NODE_22, RES_K(10), CAP_U(0.1)) DISCRETE_OUTPUT(NODE_80, 2500) DISCRETE_SOUND_END void alinvade_state::sound_w(uint8_t data) { m_discrete->write(NODE_01, (data^0x3f)<<2); } void alinvade_state::sounden_w(uint8_t data) { machine().sound().system_mute(data != 4); } uint8_t alinvade_state::irqmask_r() { return 0; // TODO: might be anything } void alinvade_state::irqmask_w(uint8_t data) { if((!(m_irqff & 1)) && (data & 1)) // f/f, active high? If the above actually returns 0xff this could be active low ... m_irqmask^= 1; m_irqff = data; } void alinvade_state::alinvade_map(address_map &map) { map(0x0000, 0x01ff).ram(); map(0x0400, 0x0bff).ram().share("videoram"); map(0x0c00, 0x0dff).ram(); map(0x2000, 0x2000).w(FUNC(alinvade_state::sound_w)); map(0x4000, 0x4000).portr("COIN"); map(0x6000, 0x6000).portr("DSW"); map(0x8000, 0x8000).portr("IN0"); map(0x8001, 0x8001).portr("IN1"); map(0x8002, 0x8002).portr("IN2"); map(0x8003, 0x8003).portr("IN3"); map(0x8004, 0x8004).portr("IN4"); map(0xa000, 0xa000).nopw(); //?? map(0xc000, 0xc00f).mirror(0xff0).rom().region("proms", 0); map(0xe000, 0xe3ff).rom(); map(0xe400, 0xe400).w(FUNC(alinvade_state::sounden_w)); map(0xe800, 0xe800).rw(FUNC(alinvade_state::irqmask_r), FUNC(alinvade_state::irqmask_w)); //?? map(0xec00, 0xffff).rom(); } static INPUT_PORTS_START( alinvade ) PORT_START("COIN") PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_COIN1 ) PORT_BIT(0xef, IP_ACTIVE_LOW, IPT_UNKNOWN ) PORT_START("IN0") PORT_BIT(0x20, IP_ACTIVE_HIGH, IPT_BUTTON1 ) PORT_PLAYER(1) PORT_BIT(0xdf, IP_ACTIVE_HIGH, IPT_UNKNOWN ) PORT_START("IN1") PORT_BIT(0x20, IP_ACTIVE_HIGH, IPT_JOYSTICK_RIGHT ) PORT_2WAY PORT_PLAYER(1) PORT_BIT(0xdf, IP_ACTIVE_HIGH, IPT_UNKNOWN ) PORT_START("IN2") PORT_BIT(0x20, IP_ACTIVE_HIGH, IPT_JOYSTICK_LEFT ) PORT_2WAY PORT_PLAYER(1) PORT_BIT(0xdf, IP_ACTIVE_HIGH, IPT_UNKNOWN ) PORT_START("IN3") PORT_BIT(0x20, IP_ACTIVE_HIGH, IPT_START1 ) PORT_BIT(0xdf, IP_ACTIVE_HIGH, IPT_UNKNOWN ) PORT_START("IN4") PORT_BIT(0x20, IP_ACTIVE_HIGH, IPT_START2 ) PORT_BIT(0xdf, IP_ACTIVE_HIGH, IPT_UNKNOWN ) PORT_START("DSW") PORT_DIPNAME( 0x03, 0x01, DEF_STR( Lives ) ) PORT_DIPSETTING( 0x00, "2" ) PORT_DIPSETTING( 0x01, "3" ) PORT_DIPSETTING( 0x02, "4" ) PORT_DIPSETTING( 0x03, "5" ) PORT_DIPNAME( 0x04, 0x04, DEF_STR ( Bonus_Life ) ) PORT_DIPSETTING( 0x04, "10k" ) PORT_DIPSETTING( 0x00, "13k" ) PORT_BIT( 0xf8, IP_ACTIVE_HIGH, IPT_UNUSED ) INPUT_PORTS_END void alinvade_state::machine_start() { save_item(NAME(m_irqff)); save_item(NAME(m_irqmask)); } void alinvade_state::machine_reset() { m_irqmask = 1; } uint32_t alinvade_state::screen_update(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect) { for (offs_t offs = 0; offs < m_videoram.bytes(); offs++) { uint8_t x = (offs << 3)&0x7f; int y = (offs >> 4)&0x7f; uint8_t data = m_videoram[offs]; for (int i = 0; i < 8; i++) { pen_t pen = (data & 0x01) ? rgb_t::white() : rgb_t::black(); bitmap.pix(y, x) = pen; data >>= 1; x++; } } return 0; } void alinvade_state::vblank_irq(int state) { if (state && BIT(m_irqmask, 0)) m_maincpu->set_input_line(0,HOLD_LINE); } void alinvade_state::alinvade(machine_config &config) { /* basic machine hardware */ M6502(config, m_maincpu, 2000000); /* ? MHz */ m_maincpu->set_addrmap(AS_PROGRAM, &alinvade_state::alinvade_map); /* video hardware */ screen_device &screen(SCREEN(config, "screen", SCREEN_TYPE_RASTER)); screen.set_refresh_hz(60); screen.set_vblank_time(ATTOSECONDS_IN_USEC(0)); screen.set_size(128, 128); screen.set_visarea_full(); screen.set_screen_update(FUNC(alinvade_state::screen_update)); screen.screen_vblank().set(FUNC(alinvade_state::vblank_irq)); /* sound hardware */ SPEAKER(config, "mono").front_center(); DISCRETE(config, m_discrete, alinvade_discrete).add_route(ALL_OUTPUTS, "mono", 1.0); } ROM_START( alinvade ) ROM_REGION( 0x10000, "maincpu", 0 ) // todo, check mapping 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 GAMEL( 198?, alinvade, 0, alinvade, alinvade, alinvade_state, empty_init, ROT90, "Forbes?", "Alien Invaders", MACHINE_UNEMULATED_PROTECTION | MACHINE_IMPERFECT_SOUND | MACHINE_SUPPORTS_SAVE, layout_alinvade )