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-rw-r--r--src/devices/machine/74543.cpp117
1 files changed, 117 insertions, 0 deletions
diff --git a/src/devices/machine/74543.cpp b/src/devices/machine/74543.cpp
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+++ b/src/devices/machine/74543.cpp
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+// license:BSD-3-Clause
+// copyright-holders:Michael Zapf
+/*****************************************************************************
+
+ 74543: Octal Registered Transceiver
+ (typically 74F543)
+
+*****************************************************************************/
+
+#include "emu.h"
+#include "74543.h"
+
+DEFINE_DEVICE_TYPE(TTL74543, ttl74543_device, "ttl74543", "Octal Registered Transceiver")
+
+ttl74543_device::ttl74543_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+ : device_t(mconfig, TTL74543, tag, owner, clock),
+ m_output_a(*this),
+ m_output_b(*this),
+ m_ceabpre(false),
+ m_leabpre(false),
+ m_oeabpre(false),
+ m_cebapre(false),
+ m_lebapre(false),
+ m_oebapre(false)
+{
+}
+
+void ttl74543_device::device_start()
+{
+ save_item(NAME(m_ceab));
+ save_item(NAME(m_leab));
+ save_item(NAME(m_oeab));
+ save_item(NAME(m_ceba));
+ save_item(NAME(m_leba));
+ save_item(NAME(m_oeba));
+
+ save_item(NAME(m_latch));
+}
+
+void ttl74543_device::device_reset()
+{
+ m_ceab = m_ceabpre;
+ m_leab = m_leabpre;
+ m_oeab = m_oeabpre;
+ m_ceba = m_cebapre;
+ m_leba = m_lebapre;
+ m_oeba = m_oebapre;
+}
+
+/*
+ Data I/O control table:
+
+ Inputs Latch Output
+ CEAB* LEAB* OEAB* Status Buffers
+ -----------------------------------------
+ H X X Latched High Z A->B flow shown
+ X H X Latched - B->A flow control is the same
+ L L X Transparent - except using CEBA*, LEBA*, OEBA*
+ X X H - High Z
+ L X L - Driving
+
+ X = immaterial
+*/
+
+void ttl74543_device::a_w(uint8_t a)
+{
+ if (m_ceab && m_leab) m_latch = a;
+}
+
+void ttl74543_device::b_w(uint8_t b)
+{
+ if (m_ceba && m_leba) m_latch = b;
+}
+
+void ttl74543_device::outputb_rz(uint8_t& value)
+{
+ if (m_ceab && m_oeab) value = m_latch;
+}
+
+void ttl74543_device::outputa_rz(uint8_t& value)
+{
+ if (m_ceba && m_oeba) value = m_latch;
+}
+
+void ttl74543_device::ceab_w(int state)
+{
+ m_ceab = (state == 0);
+ if (m_ceab && m_oeab) m_output_b(m_latch);
+}
+
+void ttl74543_device::leab_w(int state)
+{
+ m_leab = (state == 0);
+}
+
+void ttl74543_device::oeab_w(int state)
+{
+ m_oeab = (state == 0);
+ if (m_ceab && m_oeab) m_output_b(m_latch);
+}
+
+void ttl74543_device::ceba_w(int state)
+{
+ m_ceba = (state == 0);
+ if (m_ceba && m_oeba) m_output_a(m_latch);
+}
+
+void ttl74543_device::leba_w(int state)
+{
+ m_leba = (state == 0);
+}
+
+void ttl74543_device::oeba_w(int state)
+{
+ m_oeba = (state == 0);
+ if (m_ceba && m_oeba) m_output_a(m_latch);
+}