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// license:BSD-3-Clause
// copyright-holders:Curt Coder
/**********************************************************************
MM74C922/MM74C923 16/20-Key Encoder emulation
**********************************************************************
_____ _____
ROW Y1 1 |* \_/ | 18 Vcc
ROW Y2 2 | | 17 DATA OUT A
ROW Y3 3 | | 16 DATA OUT B
ROW Y4 4 | | 15 DATA OUT C
OSCILLATOR 5 | MM74C922 | 14 DATA OUT D
KEYBOUNCE MASK 6 | | 13 _OUTPUT ENABLE
COLUMN X4 7 | | 12 DATA AVAILABLE
COLUMN X3 8 | | 11 COLUMN X1
GND 9 |_____________| 10 COLUMN X2
_____ _____
ROW Y1 1 |* \_/ | 20 Vcc
ROW Y2 2 | | 19 DATA OUT A
ROW Y3 3 | | 18 DATA OUT B
ROW Y4 4 | | 17 DATA OUT C
ROW Y5 5 | MM74C923 | 16 DATA OUT D
OSCILLATOR 6 | | 15 DATA OUT E
KEYBOUNCE MASK 7 | | 14 _OUTPUT ENABLE
COLUMN X4 8 | | 13 DATA AVAILABLE
COLUMN X3 9 | | 12 COLUMN X1
GND 10 |_____________| 11 COLUMN X2
**********************************************************************/
#ifndef MAME_MACHINE_MM74C922_H
#define MAME_MACHINE_MM74C922_H
#pragma once
//**************************************************************************
// TYPE DEFINITIONS
//**************************************************************************
// ======================> mm74c922_device
class mm74c922_device : public device_t
{
public:
// construction/destruction
mm74c922_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
void set_cap_osc(double value) { m_cap_osc = value; }
void set_cap_debounce(double value) { m_cap_debounce = value; }
auto da_wr_callback() { return m_write_da.bind(); }
auto x1_rd_callback() { return m_read_x[0].bind(); }
auto x2_rd_callback() { return m_read_x[1].bind(); }
auto x3_rd_callback() { return m_read_x[2].bind(); }
auto x4_rd_callback() { return m_read_x[3].bind(); }
uint8_t read();
DECLARE_READ_LINE_MEMBER(da_r) { return m_da; }
protected:
mm74c922_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock, int max_y);
// device-level overrides
virtual void device_start() override;
virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) override;
private:
void change_output_lines();
void clock_scan_counters();
void detect_keypress();
devcb_write_line m_write_da;
devcb_read8::array<4> m_read_x;
double m_cap_osc;
double m_cap_debounce;
const int m_max_y;
bool m_inhibit; // scan counter clock inhibit
int m_x; // currently scanned column
int m_y; // latched row
uint8_t m_data; // data latch
bool m_da; // data available flag
bool m_next_da; // next value of data available flag
// timers
emu_timer *m_scan_timer; // keyboard scan timer
};
// ======================> mm74c923_device
class mm74c923_device : public mm74c922_device
{
public:
// construction/destruction
mm74c923_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
};
// device type definition
DECLARE_DEVICE_TYPE(MM74C922, mm74c922_device)
DECLARE_DEVICE_TYPE(MM74C923, mm74c923_device)
#endif // MAME_MACHINE_MM74C922_H
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