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-rw-r--r--src/devices/machine/74153.cpp172
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diff --git a/src/devices/machine/74153.cpp b/src/devices/machine/74153.cpp
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+// license:BSD-3-Clause
+// copyright-holders:Aaron Giles
+/*****************************************************************************
+
+ 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 TTL", 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_start - device-specific startup
+//-------------------------------------------------
+
+void ttl74153_device::device_start()
+{
+ m_output_cb.bind_relative_to(*owner());
+
+ 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.isnull() &&
+ ((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();
+ }
+}
+
+
+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];
+}