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amstrad: create 8255 PPI clone based on the Amstrad Plus ASIC, and use it with the Plus and GX4000 drives. Fixes Plus detection in some games, breaks inputs in Barbarian (correct behaviour).

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This commit is contained in:
mahlemiut 2018-07-12 13:51:32 +12:00
parent 1ee5c62a21
commit 35dfa53724
3 changed files with 58 additions and 5 deletions
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39
src/devices/machine/i8255.cpp
View File

@ -299,6 +299,10 @@ void i8255_device::device_start()
save_item(NAME(m_inte1));
save_item(NAME(m_inte2));
save_item(NAME(m_intr));
m_force_portb_in = false;
m_force_portc_out = false;
m_dont_clear_output_latches = false;
}
@ -651,8 +655,18 @@ void i8255_device::set_mode(uint8_t data)
{
m_control = data;
if(m_force_portb_in)
m_control = m_control | CONTROL_PORT_B_INPUT;
if(m_force_portc_out)
{
m_control = m_control & ~CONTROL_PORT_C_UPPER_INPUT;
m_control = m_control & ~CONTROL_PORT_C_LOWER_INPUT;
}
// group A
m_output[PORT_A] = 0;
if(!m_dont_clear_output_latches)
m_output[PORT_A] = 0;
m_input[PORT_A] = 0;
m_ibf[PORT_A] = 0;
m_obf[PORT_A] = 1;
@ -678,7 +692,8 @@ void i8255_device::set_mode(uint8_t data)
LOG("I8255 Port C Lower Mode: %s\n", (port_c_lower_mode() == MODE_OUTPUT) ? "output" : "input");
// group B
m_output[PORT_B] = 0;
if(!m_dont_clear_output_latches)
m_output[PORT_B] = 0;
m_input[PORT_B] = 0;
m_ibf[PORT_B] = 0;
m_obf[PORT_B] = 1;
@ -694,7 +709,8 @@ void i8255_device::set_mode(uint8_t data)
m_out_pb_cb((offs_t)0, m_tri_pb_cb(0));
}
m_output[PORT_C] = 0;
if(!m_dont_clear_output_latches)
m_output[PORT_C] = 0;
m_input[PORT_C] = 0;
output_pc();
@ -1000,3 +1016,20 @@ WRITE_LINE_MEMBER( i8255_device::pc6_w )
}
}
}
// AMS40489 (Amstrad Plus/GX4000 ASIC PPI implementation)
ams40489_ppi_device::ams40489_ppi_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: i8255_device(mconfig,tag,owner,clock)
{}
void ams40489_ppi_device::device_reset() { i8255_device::device_reset(); }
void ams40489_ppi_device::device_start()
{
i8255_device::device_start();
m_force_portb_in = true;
m_force_portc_out = true;
m_dont_clear_output_latches = true;
}

18
src/devices/machine/i8255.h
View File

@ -111,6 +111,10 @@ protected:
virtual void device_start() override;
virtual void device_reset() override;
bool m_force_portb_in;
bool m_force_portc_out;
bool m_dont_clear_output_latches;
private:
inline void check_interrupt(int port);
inline void set_ibf(int port, int state);
@ -158,9 +162,23 @@ private:
int m_intr[2]; // interrupt
};
// AMS40489 ASIC (Amstrad Plus/GX4000 PPI implementation)
class ams40489_ppi_device : public i8255_device
{
public:
// construction/destruction
ams40489_ppi_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
protected:
// device-level overrides
virtual void device_start() override;
virtual void device_reset() override;
};
// device type definition
DECLARE_DEVICE_TYPE(I8255, i8255_device)
DECLARE_DEVICE_TYPE(I8255A, i8255_device)
DECLARE_DEVICE_TYPE(AMS40489_PPI, ams40489_ppi_device)
#endif // MAME_MACHINE_I8255_H

6
src/mame/drivers/amstrad.cpp
View File

@ -1047,7 +1047,7 @@ MACHINE_CONFIG_START(amstrad_state::cpcplus)
MCFG_MACHINE_START_OVERRIDE(amstrad_state, plus )
MCFG_MACHINE_RESET_OVERRIDE(amstrad_state, plus )
MCFG_DEVICE_ADD("ppi8255", I8255, 0)
MCFG_DEVICE_ADD("ppi8255", AMS40489_PPI, 0)
MCFG_I8255_IN_PORTA_CB(READ8(*this, amstrad_state, amstrad_ppi_porta_r))
MCFG_I8255_OUT_PORTA_CB(WRITE8(*this, amstrad_state, amstrad_ppi_porta_w))
MCFG_I8255_IN_PORTB_CB(READ8(*this, amstrad_state, amstrad_ppi_portb_r))
@ -1091,6 +1091,7 @@ MACHINE_CONFIG_START(amstrad_state::cpcplus)
MCFG_CASSETTE_FORMATS(cdt_cassette_formats)
MCFG_CASSETTE_DEFAULT_STATE(CASSETTE_STOPPED | CASSETTE_MOTOR_DISABLED | CASSETTE_SPEAKER_ENABLED)
MCFG_CASSETTE_INTERFACE("cpc_cass")
MCFG_SOFTWARE_LIST_ADD("cass_list","cpc_cass")
MCFG_UPD765A_ADD("upd765", true, true)
@ -1098,6 +1099,7 @@ MACHINE_CONFIG_START(amstrad_state::cpcplus)
MCFG_FLOPPY_DRIVE_ADD("upd765:0", amstrad_floppies, "3ssdd", floppy_image_device::default_floppy_formats)
MCFG_FLOPPY_DRIVE_ADD("upd765:1", amstrad_floppies, "35ssdd", floppy_image_device::default_floppy_formats)
MCFG_SOFTWARE_LIST_ADD("flop_list","cpc_flop")
MCFG_DEVICE_ADD("exp", CPC_EXPANSION_SLOT, 0)
MCFG_DEVICE_SLOT_INTERFACE(cpcplus_exp_cards, nullptr, false)
@ -1125,7 +1127,7 @@ MACHINE_CONFIG_START(amstrad_state::gx4000)
MCFG_MACHINE_START_OVERRIDE(amstrad_state, gx4000 )
MCFG_MACHINE_RESET_OVERRIDE(amstrad_state, gx4000 )
MCFG_DEVICE_ADD("ppi8255", I8255, 0)
MCFG_DEVICE_ADD("ppi8255", AMS40489_PPI, 0)
MCFG_I8255_IN_PORTA_CB(READ8(*this, amstrad_state, amstrad_ppi_porta_r))
MCFG_I8255_OUT_PORTA_CB(WRITE8(*this, amstrad_state, amstrad_ppi_porta_w))
MCFG_I8255_IN_PORTB_CB(READ8(*this, amstrad_state, amstrad_ppi_portb_r))