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// license:BSD-3-Clause
// copyright-holders:Couriersud
/*****************************************************************************
74123 monoflop emulator
There are 2 monoflops per chips.
Pin out:
+--------+
B1 |1 | | 16| Vcc
A1 o|2 - 15| RCext1
Clear1 o|3 14| Cext1
*Output1 o|4 13| Output1
Output2 |5 12|o *Output2
Cext2 |6 11|o Clear2
RCext2 |7 10| B2
GND |8 9|o A2
+--------+
All resistor values in Ohms.
All capacitor values in Farads.
Truth table:
C A B | Q /Q
----------|-------
L X X | L H
X H X | L H
X X L | L H
H L _- |_-_ -_-
H -_ H |_-_ -_-
_- L H |_-_ -_-
------------------
C = clear
L = LO (0)
H = HI (1)
X = any state
_- = raising edge
-_ = falling edge
_-_ = positive pulse
-_- = negative pulse
*****************************************************************************/
#ifndef MAME_MACHINE_74123_H
#define MAME_MACHINE_74123_H
#pragma once
/* constants for the different ways the cap/res can be connected.
This determines the formula for calculating the pulse width */
#define TTL74123_NOT_GROUNDED_NO_DIODE (1)
#define TTL74123_NOT_GROUNDED_DIODE (2)
#define TTL74123_GROUNDED (3)
/***************************************************************************
TYPE DEFINITIONS
***************************************************************************/
// ======================> ttl74123_device
class ttl74123_device : public device_t
{
public:
// construction/destruction
ttl74123_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
ttl74123_device(const machine_config &mconfig, const char *tag, device_t *owner, double res, double cap)
: ttl74123_device(mconfig, tag, owner, 0U)
{
set_resistor_value(res);
set_capacitor_value(cap);
}
void set_connection_type(int type) { m_connection_type = type; }
void set_resistor_value(double value) { m_res = value; }
void set_capacitor_value(double value) { m_cap = value; }
void set_a_pin_value(int value) { m_a = value; }
void set_b_pin_value(int value) { m_b = value; }
void set_clear_pin_value(int value) { m_clear = value; }
auto out_cb() { return m_output_changed_cb.bind(); }
void a_w(int state);
void b_w(int state);
void clear_w(int state);
void reset_w(int state);
int q_r() { return timer_running(); }
protected:
// device-level overrides
virtual void device_start() override ATTR_COLD;
virtual void device_reset() override ATTR_COLD;
virtual void device_post_load() override { }
virtual void device_clock_changed() override { }
TIMER_CALLBACK_MEMBER( output_callback );
TIMER_CALLBACK_MEMBER( clear_callback );
private:
int timer_running();
void start_pulse();
void set_output();
attotime compute_duration();
emu_timer *m_clear_timer;
emu_timer *m_output_timer;
int m_connection_type; /* the hook up type - one of the constants above */
double m_res; /* resistor connected to RCext */
double m_cap; /* capacitor connected to Cext and RCext */
int m_a; /* initial/constant value of the A pin */
int m_b; /* initial/constant value of the B pin */
int m_clear; /* initial/constant value of the Clear pin */
devcb_write_line m_output_changed_cb;
};
// device type definition
DECLARE_DEVICE_TYPE(TTL74123, ttl74123_device)
#endif // MAME_MACHINE_74123_H
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