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/*****************************************************************************
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, "TTL 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];
}
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