/***************************************************************************** 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 *****************************************************************************/ #pragma once #ifndef __TTL74123_H__ #define __TTL74123_H__ #include "emu.h" /*************************************************************************** DEVICE CONFIGURATION MACROS ***************************************************************************/ #define MCFG_TTL74123_ADD(_tag, _config) \ MCFG_DEVICE_ADD(_tag, TTL74123, 0) \ MCFG_DEVICE_CONFIG(_config) /* 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_interface struct ttl74123_interface { 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 */ write8_device_func m_output_changed_cb; }; // ======================> ttl74123_device class ttl74123_device : public device_t, public ttl74123_interface { public: // construction/destruction ttl74123_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock); void a_w(UINT8 data); void b_w(UINT8 data); void clear_w(UINT8 data); void reset_w(); protected: // device-level overrides virtual void device_config_complete(); virtual void device_start(); virtual void device_reset(); virtual void device_post_load() { } virtual void device_clock_changed() { } static TIMER_CALLBACK( output_callback ); static TIMER_CALLBACK( clear_callback ); private: int timer_running(); void start_pulse(); void output(INT32 param); void set_output(); attotime compute_duration(); void clear(); emu_timer *m_timer; }; // device type definition extern const device_type TTL74123; /*************************************************************************** PROTOTYPES ***************************************************************************/ WRITE8_DEVICE_HANDLER( ttl74123_a_w ); WRITE8_DEVICE_HANDLER( ttl74123_b_w ); WRITE8_DEVICE_HANDLER( ttl74123_clear_w ); WRITE8_DEVICE_HANDLER( ttl74123_reset_w ); /* reset the latch */ #endif