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// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/*****************************************************************************
7474 positive-edge-triggered D-type flip-flop with preset, clear and
complementary outputs. There are 2 flip-flops per chips
Pin layout and functions to access pins:
clear_w [1] /1CLR VCC [14]
d_w [2] 1D /2CLR [13] clear_w
clock_w [3] 1CLK 2D [12] d_w
preset_w [4] /1PR 2CLK [11] clock_w
output_r [5] 1Q /2PR [10] preset_w
output_comp_r [6] /1Q 2Q [9] output_r
[7] GND /2Q [8] output_comp_r
Truth table (all logic levels indicate the actual voltage on the line):
INPUTS | OUTPUTS
|
PR CLR CLK D | Q /Q
--------------+-------
L H X X | H L
H L X X | L H
L L X X | H H (Note 1)
H H _- X | D /D
H H L X | Q0 /Q01
--------------+-------
L = lo (0)
H = hi (1)
X = any state
_- = raising edge
Q0 = previous state
Note 1: Non-stable configuration
*****************************************************************************/
#ifndef MAME_MACHINE_7474_H
#define MAME_MACHINE_7474_H
#pragma once
//**************************************************************************
// TYPE DEFINITIONS
//**************************************************************************
// ======================> ttl7474_device
class ttl7474_device : public device_t
{
public:
// construction/destruction
ttl7474_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
// static configuration helpers
auto output_cb() { return m_output_func.bind(); }
auto comp_output_cb() { return m_comp_output_func.bind(); }
// public interfaces
void clear_w(int state);
void preset_w(int state);
void clock_w(int state);
void d_w(int state);
int output_r();
int output_comp_r(); // NOT strictly the same as !output_r()
protected:
// device_t implementation
virtual void device_start() override ATTR_COLD;
virtual void device_reset() override ATTR_COLD;
private:
// callbacks
devcb_write_line m_output_func;
devcb_write_line m_comp_output_func;
// inputs
uint8_t m_clear; // pin 1/13
uint8_t m_preset; // pin 4/10
uint8_t m_clk; // pin 3/11
uint8_t m_d; // pin 2/12
// outputs
uint8_t m_output; // pin 5/9
uint8_t m_output_comp; // pin 6/8
// internal
uint8_t m_last_clock;
uint8_t m_last_output;
uint8_t m_last_output_comp;
void update();
void init();
};
// device type definition
DECLARE_DEVICE_TYPE(TTL7474, ttl7474_device)
#endif // MAME_MACHINE_7474_H
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