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mrdo.cpp: Removed protection hack and replaced with logic from PAL dump. (#9139)

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This commit is contained in:
Darren Olafson 2022-01-18 09:22:50 -08:00 committed by GitHub
parent cd51627f28
commit eb89e1ac31
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 64 additions and 15 deletions
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26
src/mame/drivers/mrdo.cpp
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@ -38,19 +38,6 @@ constexpr XTAL VIDEO_CLOCK = 19.6_MHz_XTAL;
} // anonymous namespace
/* PAL16R6CN used for protection. The game doesn't clear the screen
if a read from this address doesn't return the value it expects. */
uint8_t mrdo_state::mrdo_SECRE_r()
{
uint8_t *RAM = memregion("maincpu")->base();
return RAM[m_maincpu->state_int(Z80_HL)];
}
void mrdo_state::main_map(address_map &map)
{
map(0x0000, 0x7fff).rom();
@ -60,7 +47,7 @@ void mrdo_state::main_map(address_map &map)
map(0x9800, 0x9800).w(FUNC(mrdo_state::mrdo_flipscreen_w)); // screen flip + playfield priority
map(0x9801, 0x9801).w("sn1", FUNC(sn76489_device::write));
map(0x9802, 0x9802).w("sn2", FUNC(sn76489_device::write));
map(0x9803, 0x9803).r(FUNC(mrdo_state::mrdo_SECRE_r));
map(0x9803, 0x9803).r(FUNC(mrdo_state::mrdo_secre_r));
map(0xa000, 0xa000).portr("P1");
map(0xa001, 0xa001).portr("P2");
map(0xa002, 0xa002).portr("DSW1");
@ -199,6 +186,17 @@ void mrdo_state::mrdo(machine_config &config)
SN76489(config, "sn2", MAIN_CLOCK/2).add_route(ALL_OUTPUTS, "mono", 0.50); // Verified
}
void mrdo_state::machine_start()
{
save_item(NAME(m_pal_u001));
}
void mrdo_state::machine_reset()
{
// initial outputs are high on power-up
m_pal_u001 = 0xff;
}
void mrdo_state::mrlo(machine_config &config)
{
mrdo(config);

7
src/mame/includes/mrdo.h
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@ -33,6 +33,9 @@ public:
protected:
virtual void video_start() override;
virtual void machine_start() override;
virtual void machine_reset() override;
private:
// memory pointers
required_shared_ptr<uint8_t> m_bgvideoram;
@ -47,8 +50,10 @@ private:
tilemap_t *m_bg_tilemap;
tilemap_t *m_fg_tilemap;
int m_flipscreen;
uint8_t m_pal_u001;
uint8_t mrdo_secre_r();
uint8_t mrdo_SECRE_r();
void mrdo_bgvideoram_w(offs_t offset, uint8_t data);
void mrdo_fgvideoram_w(offs_t offset, uint8_t data);
void mrdo_scrollx_w(uint8_t data);

46
src/mame/video/mrdo.cpp
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@ -185,13 +185,59 @@ void mrdo_state::mrdo_bgvideoram_w(offs_t offset, uint8_t data)
m_bg_tilemap->mark_tile_dirty(offset & 0x3ff);
}
/* PAL16R6CN used for protection. The game doesn't clear the screen
if a read from this address doesn't return the value it expects. */
uint8_t mrdo_state::mrdo_secre_r()
{
return m_pal_u001;
}
void mrdo_state::mrdo_fgvideoram_w(offs_t offset, uint8_t data)
{
m_fgvideoram[offset] = data;
m_fg_tilemap->mark_tile_dirty(offset & 0x3ff);
// protection. each write latches a new value on IC u001 (PAL16R6)
const uint8_t i9 = BIT(data,0);
const uint8_t i8 = BIT(data,1);
// const uint8_t i7 = BIT(data,2); pin 7 not used in equations
const uint8_t i6 = BIT(data,3);
const uint8_t i5 = BIT(data,4);
const uint8_t i4 = BIT(data,5);
const uint8_t i3 = BIT(data,6);
const uint8_t i2 = BIT(data,7);
// equations extracted from dump using jedutil
const uint8_t t1 = i2 & (1^i3) & i4 & (1^i5) & (1^i6) & (1^i8) & i9;
const uint8_t t2 = (1^i2) & (1^i3) & i4 & i5 & (1^i6) & i8 & (1^i9);
const uint8_t t3 = i2 & i3 & (1^i4) & (1^i5) & i6 & (1^i8) & i9;
const uint8_t t4 = (1^i2) & i3 & i4 & (1^i5) & i6 & i8 & i9;
const uint8_t r12 = 0;
const uint8_t r13 = (1^( t1 )) << 1 ;
const uint8_t r14 = (1^( t1 | t2 )) << 2 ;
const uint8_t r15 = (1^( t1 | t3 )) << 3 ;
const uint8_t r16 = (1^( t1 )) << 4 ;
const uint8_t r17 = (1^( t1 | t3 )) << 5 ;
const uint8_t r18 = (1^( t3 | t4 )) << 6 ;
const uint8_t r19 = 0;
m_pal_u001 = r19 | r18 | r17 | r16 | r15 | r14 | r13 | r12 ;
}
/*
/rf13 := i2 & /i3 & i4 & /i5 & /i6 & /i8 & i9 t1
/rf14 := /i2 & /i3 & i4 & i5 & /i6 & i8 & /i9 + i2 & /i3 & i4 & /i5 & /i6 & /i8 & i9 t2 | t1
/rf15 := i2 & i3 & /i4 & /i5 & i6 & /i8 & i9 + i2 & /i3 & i4 & /i5 & /i6 & /i8 & i9 t3 | t1
/rf16 := i2 & /i3 & i4 & /i5 & /i6 & /i8 & i9 t1
/rf17 := i2 & i3 & /i4 & /i5 & i6 & /i8 & i9 + i2 & /i3 & i4 & /i5 & /i6 & /i8 & i9 t3 | t1
/rf18 := /i2 & i3 & i4 & /i5 & i6 & i8 & i9 + i2 & i3 & /i4 & /i5 & i6 & /i8 & i9 t4 | t2
*/
void mrdo_state::mrdo_scrollx_w(uint8_t data)
{
m_bg_tilemap->set_scrollx(0, data);