summaryrefslogtreecommitdiffstatshomepage
path: root/src/emu/machine/74153.c
blob: 9d21cfc63871125811fa9aae8bf1b4789e6e3124 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
/*****************************************************************************

  74153 Dual 4-line to 1-line data selectors/multiplexers


  Pin layout and functions to access pins:

  enable_w(0)        [1] /1G   VCC [16]
  b_w                [2] B     /2G [15]  enable_w(1)
  input_line_w(0,3)  [3] 1C3     A [14]  a_w
  input_line_w(0,2)  [4] 1C2   2C3 [13]  input_line_w(1,3)
  input_line_w(0,1)  [5] 1C1   2C2 [12]  input_line_w(1,2)
  input_line_w(0,0)  [6] 1C0   2C1 [11]  input_line_w(1,1)
  output_r(0)        [7] 1Y    2C0 [10]  input_line_w(1,0)
                     [8] GND    2Y [9]   output_r(1)


  Truth table (all logic levels indicate the actual voltage on the line):

            INPUTS         | OUTPUT
                           |
    G | B  A | C0 C1 C2 C3 | Y
    --+------+-------------+---
1   H | X  X | X  X  X  X  | L
2   L | L  L | X  X  X  X  | C0
3   L | L  H | X  X  X  X  | C1
4   L | H  L | X  X  X  X  | C2
5   L | H  H | X  X  X  X  | C3
    --+------+-------------+---
    L   = lo (0)
    H   = hi (1)
    X   = any state

*****************************************************************************/

#include "emu.h"
#include "machine/74153.h"


const device_type TTL74153 = &device_creator<ttl74153_device>;

ttl74153_device::ttl74153_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
	: device_t(mconfig, TTL74153, "74153", tag, owner, clock, "74153", __FILE__),
	m_a(0),
	m_b(0)
{
	m_input_lines[0][0] = 0;
	m_input_lines[0][1] = 0;
	m_input_lines[0][2] = 0;
	m_input_lines[0][3] = 0;
	m_input_lines[1][0] = 0;
	m_input_lines[1][1] = 0;
	m_input_lines[1][2] = 0;
	m_input_lines[1][3] = 0;

	for (int i = 0; i < 2; i++)
	m_enable[i] = 0;

	for (int i = 0; i < 2; i++)
	m_output[i] = 0;

	for (int i = 0; i < 2; i++)
	m_last_output[i] = 0;
}

//-------------------------------------------------
//  device_config_complete - perform any
//  operations now that the configuration is
//  complete
//-------------------------------------------------

void ttl74153_device::device_config_complete()
{
	// inherit a copy of the static data
	const ttl74153_config *intf = reinterpret_cast<const ttl74153_config *>(static_config());
	if (intf != NULL)
	*static_cast<ttl74153_config *>(this) = *intf;

	// or initialize to defaults if none provided
	else
	{
	}
}

//-------------------------------------------------
//  device_start - device-specific startup
//-------------------------------------------------

void ttl74153_device::device_start()
{
	save_item(NAME(m_enable));
	save_item(NAME(m_last_output));
	save_item(NAME(m_input_lines[0][0]));
	save_item(NAME(m_input_lines[0][1]));
	save_item(NAME(m_input_lines[0][2]));
	save_item(NAME(m_input_lines[0][3]));
	save_item(NAME(m_input_lines[1][0]));
	save_item(NAME(m_input_lines[1][1]));
	save_item(NAME(m_input_lines[1][2]));
	save_item(NAME(m_input_lines[1][3]));
	save_item(NAME(m_a));
	save_item(NAME(m_b));
}

//-------------------------------------------------
//  device_reset - device-specific reset
//-------------------------------------------------

void ttl74153_device::device_reset()
{
	m_a = 1;
	m_b = 1;
	m_enable[0] = 1;
	m_enable[1] = 1;
	m_input_lines[0][0] = 1;
	m_input_lines[0][1] = 1;
	m_input_lines[0][2] = 1;
	m_input_lines[0][3] = 1;
	m_input_lines[1][0] = 1;
	m_input_lines[1][1] = 1;
	m_input_lines[1][2] = 1;
	m_input_lines[1][3] = 1;

	m_last_output[0] = -1;
	m_last_output[1] = -1;
}


void ttl74153_device::update()
{
	int sel;
	int section;


	sel = (m_b << 1) | m_a;


	/* process both sections */
	for (section = 0; section < 2; section++)
	{
		if (m_enable[section])
			m_output[section] = 0; // row 1 in truth table
		else
			m_output[section] = m_input_lines[section][sel];
	}


	/* call callback if either of the outputs changed */
	if (  m_output_cb &&
		((m_output[0] != m_last_output[0]) ||
			(m_output[1] != m_last_output[1])))
	{
		m_last_output[0] = m_output[0];
		m_last_output[1] = m_output[1];

		m_output_cb(this);
	}
}


void ttl74153_device::a_w(int data)
{
	m_a = data ? 1 : 0;
}


void ttl74153_device::b_w(int data)
{
	m_b = data ? 1 : 0;
}


void ttl74153_device::input_line_w(int section, int input_line, int data)
{
	m_input_lines[section][input_line] = data ? 1 : 0;
}


void ttl74153_device::enable_w(int section, int data)
{
	m_enable[section] = data ? 1 : 0;
}


int ttl74153_device::output_r(int section)
{
	return m_output[section];
}