diff options
Diffstat (limited to 'src/devices/machine/74153.cpp')
-rw-r--r-- | src/devices/machine/74153.cpp | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/src/devices/machine/74153.cpp b/src/devices/machine/74153.cpp new file mode 100644 index 00000000000..e38194f5d6e --- /dev/null +++ b/src/devices/machine/74153.cpp @@ -0,0 +1,172 @@ +// 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]; +} |