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-rw-r--r--src/devices/machine/mm74c922.cpp24
-rw-r--r--src/devices/machine/mm74c922.h1
-rw-r--r--src/mame/drivers/saitek_intchess.cpp10
3 files changed, 22 insertions, 13 deletions
diff --git a/src/devices/machine/mm74c922.cpp b/src/devices/machine/mm74c922.cpp
index 6cd55c3157d..a229b01a232 100644
--- a/src/devices/machine/mm74c922.cpp
+++ b/src/devices/machine/mm74c922.cpp
@@ -34,15 +34,15 @@ DEFINE_DEVICE_TYPE(MM74C923, mm74c923_device, "mm74c923", "MM74C923 20-Key Encod
mm74c922_device::mm74c922_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock, int max_y) :
device_t(mconfig, type, tag, owner, clock),
- m_write_da(*this),
- m_read_x(*this),
+ m_write_da(*this), m_read_x(*this),
m_cap_osc(0), m_cap_debounce(0),
m_max_y(max_y),
m_inhibit(false),
m_x(0),
- m_y(0), m_data(0),
- m_da(false),
- m_next_da(false), m_scan_timer(nullptr)
+ m_y(0),
+ m_data(0), m_next_data(0),
+ m_da(false), m_next_da(false),
+ m_scan_timer(nullptr)
{
}
@@ -79,6 +79,7 @@ void mm74c922_device::device_start()
save_item(NAME(m_x));
save_item(NAME(m_y));
save_item(NAME(m_data));
+ save_item(NAME(m_next_data));
save_item(NAME(m_da));
save_item(NAME(m_next_da));
}
@@ -123,6 +124,12 @@ void mm74c922_device::change_output_lines()
// active high output
m_write_da(m_da ? 1 : 0);
}
+
+ // clock data latches
+ if (m_next_data != m_data)
+ {
+ m_data = m_next_data;
+ }
}
@@ -156,7 +163,7 @@ void mm74c922_device::detect_keypress()
// key released
m_inhibit = false;
m_next_da = false;
- m_data = 0xff; // high-Z
+ m_next_data = (1 << m_max_y) - 1; // high-Z
LOG("MM74C922 Key Released\n");
}
@@ -172,10 +179,9 @@ void mm74c922_device::detect_keypress()
m_next_da = true;
m_y = y;
- m_data = (y << 2) | m_x;
+ m_next_data = (y << 2) | m_x;
- LOG("MM74C922 Key Depressed: X %u Y %u = %02x\n", m_x, y, m_data);
- return;
+ LOG("MM74C922 Key Depressed: X %u Y %u = %02x\n", m_x, y, m_next_data);
}
}
}
diff --git a/src/devices/machine/mm74c922.h b/src/devices/machine/mm74c922.h
index cd419f61074..01ada83c743 100644
--- a/src/devices/machine/mm74c922.h
+++ b/src/devices/machine/mm74c922.h
@@ -86,6 +86,7 @@ private:
int m_y; // latched row
uint8_t m_data; // data latch
+ uint8_t m_next_data; // next value of data latch
bool m_da; // data available flag
bool m_next_da; // next value of data available flag
diff --git a/src/mame/drivers/saitek_intchess.cpp b/src/mame/drivers/saitek_intchess.cpp
index 3f0dd52fe0a..93f1a0bbf97 100644
--- a/src/mame/drivers/saitek_intchess.cpp
+++ b/src/mame/drivers/saitek_intchess.cpp
@@ -18,7 +18,8 @@ Hardware notes:
- 4-digit 7seg display
TODO:
-- remove nmistate workaround when 6502 NMI is fixed
+- 6502 CPU core NMI isn't working properly at the moment, it acts like a hold_line,
+ m_nmistate can be removed once that is fixed
- colors are estimated from photos (black and white are obvious, but the green
and cyan are not standard 0x00ff00 / 0x00ffff)
- video timing is unknown, sprite offsets are estimated from photos
@@ -100,6 +101,7 @@ private:
u8 m_select = 0;
u8 m_7seg_data = 0;
+ bool m_nmistate = false;
};
void intchess_state::machine_start()
@@ -107,6 +109,7 @@ void intchess_state::machine_start()
// register for savestates
save_item(NAME(m_select));
save_item(NAME(m_7seg_data));
+ save_item(NAME(m_nmistate));
}
INPUT_CHANGED_MEMBER(intchess_state::reset_button)
@@ -205,13 +208,12 @@ u8 intchess_state::control_r()
TIMER_DEVICE_CALLBACK_MEMBER(intchess_state::cass_input)
{
// cassette input is tied to NMI
- static bool nmistate = false;
bool state = ((m_cass->get_state() & CASSETTE_MASK_UISTATE) == CASSETTE_PLAY) && (m_cass->input() < -0.04);
- if (state != nmistate)
+ if (state != m_nmistate)
{
m_maincpu->set_input_line(INPUT_LINE_NMI, state ? ASSERT_LINE : CLEAR_LINE);
- nmistate = state;
+ m_nmistate = state;
}
}