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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
*****************************************************************************/
#pragma once
#ifndef __TTL7474_H__
#define __TTL7474_H__
//**************************************************************************
// INTERFACE CONFIGURATION MACROS
//**************************************************************************
#define MCFG_7474_OUTPUT_CB(_devcb) \
devcb = &ttl7474_device::set_output_cb(*device, DEVCB_##_devcb);
#define MCFG_7474_COMP_OUTPUT_CB(_devcb) \
devcb = &ttl7474_device::set_comp_output_cb(*device, DEVCB_##_devcb);
//**************************************************************************
// 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
template<class _Object> static devcb_base &set_output_cb(device_t &device, _Object object) { return downcast<ttl7474_device &>(device).m_output_func.set_callback(object); }
template<class _Object> static devcb_base &set_comp_output_cb(device_t &device, _Object object) { return downcast<ttl7474_device &>(device).m_comp_output_func.set_callback(object); }
// public interfaces
DECLARE_WRITE_LINE_MEMBER( clear_w );
DECLARE_WRITE_LINE_MEMBER( preset_w );
DECLARE_WRITE_LINE_MEMBER( clock_w );
DECLARE_WRITE_LINE_MEMBER( d_w );
DECLARE_READ_LINE_MEMBER( output_r );
DECLARE_READ_LINE_MEMBER( output_comp_r ); // NOT strictly the same as !output_r()
protected:
// device-level overrides
virtual void device_start() override;
virtual void device_reset() override;
virtual void device_post_load() override { }
virtual void device_clock_changed() override { }
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
extern const device_type TTL7474;
#endif /* __TTL7474_H__ */
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