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i8212: Device overhaul (nw)
- Change the mode setting from a line write to an input callback. This is based on the observation that MD is nearly always tied to either Vcc or GND on actual hardware. - Make the mode a scoped enumeration. - Add strobed write handler for input mode. This allows the device to be hooked up in supstarf in place of generic_latch_8_device. - Add interrupt acknowledge callback for future use. - Add extensive introductory comments.
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AJR
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@ -1,8 +1,40 @@
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// license:BSD-3-Clause
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// copyright-holders:Curt Coder
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// copyright-holders:Curt Coder,AJR
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/**********************************************************************
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Intel 8212 8-Bit Input/Output Port emulation
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Intel 8212/3212 8-Bit Input/Output Port (Multi-Mode Latch Buffer)
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The Intel 8212 was one of the first in a line of bipolar Schottky
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peripherals released early on for the 8080. Many of these were
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assigned alternate part numbers in the 3200 series to identify
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them with Intel's 3001/3002 bipolar bit-slice processing elements.
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The 8212's MD pin is typically tied to either GND or Vcc to fix
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the chip in one of its two operating modes. In the input mode
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(MD = L), data is latched on the falling edge of STB, and the
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three-state outputs are enabled by a combination of two chip
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select inputs of opposite polarities. In the output mode (MD = H),
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data is latched on the falling edge of chip selection, and outputs
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are always enabled. The service request flip-flop is clocked on
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the falling edge of STB to produce the INT output, and is reset by
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either chip selection or the active-low CLR input, the latter
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also resetting the latched data to zero.
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The 8212 in output mode was often used with the 8080 to latch the
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status word and with the 8085 to latch the lower address bits.
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RCA's CDP1852 is an almost pin-for-pin CMOS counterpart to the
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8212. The control lines of the CDP1852, however, work slightly
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differently, especially in output mode.
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When TI second-sourced the 8080A, they cloned the 8212 as the
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SN74S412 (and numbered their versions of the 8224, 8228 and 8338
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similarly). While simpler octal latches from the 7400 series such
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as 74LS273, 74LS373 and 74LS374 became far more common and widely
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used, even when a separate service request flip-flop needed to be
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coupled, the Fairchild Advanced Schottky TTL (FAST) evolution of
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the 7400 series had both inverting (74F432) and non-inverting
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(74F412) versions of this device.
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**********************************************************************/
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@ -19,7 +51,7 @@
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//**************************************************************************
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// device type definition
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DEFINE_DEVICE_TYPE(I8212, i8212_device, "i8212", "Intel 8212 I/O")
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DEFINE_DEVICE_TYPE(I8212, i8212_device, "i8212", "Intel 8212 I/O Port")
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//-------------------------------------------------
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// i8212_device - constructor
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@ -30,8 +62,8 @@ i8212_device::i8212_device(const machine_config &mconfig, const char *tag, devic
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m_write_int(*this),
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m_read_di(*this),
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m_write_do(*this),
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m_md(MODE_INPUT),
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m_stb(0), m_data(0)
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m_read_md(*this),
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m_stb(1), m_data(0)
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{
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}
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@ -46,23 +78,37 @@ void i8212_device::device_start()
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m_write_int.resolve_safe();
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m_read_di.resolve_safe(0);
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m_write_do.resolve_safe();
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m_read_md.resolve_safe(0);
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// register for state saving
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save_item(NAME(m_md));
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save_item(NAME(m_stb));
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save_item(NAME(m_data));
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}
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//-------------------------------------------------
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// get_mode - resolve device mode
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//-------------------------------------------------
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i8212_device::mode i8212_device::get_mode()
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{
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return m_read_md() ? mode::OUTPUT : mode::INPUT;
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}
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//-------------------------------------------------
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// device_reset - device-specific reset
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//-------------------------------------------------
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void i8212_device::device_reset()
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{
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// clear interrupt line
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m_write_int(CLEAR_LINE);
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// clear latched data
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m_data = 0;
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if (m_md == MODE_OUTPUT)
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if (get_mode() == mode::OUTPUT)
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{
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// output data
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m_write_do((offs_t)0, m_data);
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@ -74,13 +120,28 @@ void i8212_device::device_reset()
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// read - data latch read
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//-------------------------------------------------
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READ8_MEMBER( i8212_device::read )
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READ8_MEMBER(i8212_device::read)
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{
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if (!machine().side_effect_disabled())
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{
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// clear interrupt line
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m_write_int(CLEAR_LINE);
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}
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return m_data;
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}
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//-------------------------------------------------
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// inta_cb - data latch read (INTA triggered)
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//-------------------------------------------------
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IRQ_CALLBACK_MEMBER(i8212_device::inta_cb)
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{
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// clear interrupt line
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m_write_int(CLEAR_LINE);
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LOG("I8212 INT: %u\n", CLEAR_LINE);
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// read latched data as interrupt vector
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return m_data;
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}
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@ -89,25 +150,37 @@ READ8_MEMBER( i8212_device::read )
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// write - data latch write
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//-------------------------------------------------
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WRITE8_MEMBER( i8212_device::write )
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WRITE8_MEMBER(i8212_device::write)
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{
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// latch data
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m_data = data;
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// clear interrupt line
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m_write_int(CLEAR_LINE);
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// output data
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m_write_do((offs_t)0, m_data);
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if (get_mode() == mode::OUTPUT)
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{
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// latch data
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m_data = data;
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LOG("I8212: Writing %02X into latch (output mode)\n", data);
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// output data
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m_write_do((offs_t)0, m_data);
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}
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}
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//-------------------------------------------------
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// md_w - mode write
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// strobe - data input strobe
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//-------------------------------------------------
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WRITE_LINE_MEMBER( i8212_device::md_w )
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WRITE8_MEMBER(i8212_device::strobe)
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{
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LOG("I8212 Mode: %s\n", state ? "output" : "input");
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if (get_mode() == mode::INPUT)
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{
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m_data = data;
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LOG("I8212: Writing %02X into latch (input mode)\n", data);
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}
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m_md = state;
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// assert interrupt line
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m_write_int(ASSERT_LINE);
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}
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@ -115,22 +188,20 @@ WRITE_LINE_MEMBER( i8212_device::md_w )
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// stb_w - data strobe write
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//-------------------------------------------------
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WRITE_LINE_MEMBER( i8212_device::stb_w )
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WRITE_LINE_MEMBER(i8212_device::stb_w)
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{
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LOG("I8212 STB: %u\n", state);
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if (m_md == MODE_INPUT)
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// active on falling edge
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if (m_stb && !state)
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{
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if (m_stb && !state)
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if (get_mode() == mode::INPUT)
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{
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// input data
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m_data = m_read_di(0);
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// assert interrupt line
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m_write_int(ASSERT_LINE);
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LOG("I8212 INT: %u\n", ASSERT_LINE);
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LOG("I8212: Reading %02X into latch (input mode)\n", m_data);
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}
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// assert interrupt line
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m_write_int(ASSERT_LINE);
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}
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m_stb = state;
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@ -1,8 +1,8 @@
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// license:BSD-3-Clause
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// copyright-holders:Curt Coder
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// copyright-holders:Curt Coder,AJR
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/**********************************************************************
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Intel 8212 8-Bit Input/Output Port emulation
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Intel 8212/3212 8-Bit Input/Output Port (Multi-Mode Latch Buffer)
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**********************************************************************
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_____ _____
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@ -12,7 +12,7 @@
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DO1 4 | | 21 DO8
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DI2 5 | | 20 DI7
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DO2 6 | 8212 | 19 DO7
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DI3 7 | | 18 DI6
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DI3 7 | 3212 | 18 DI6
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DO3 8 | | 17 DO6
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DI4 9 | | 16 DI5
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DO4 10 | | 15 DO5
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@ -42,6 +42,9 @@
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#define MCFG_I8212_DO_CALLBACK(_write) \
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devcb = &i8212_device::set_do_wr_callback(*device, DEVCB_##_write);
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#define MCFG_I8212_MD_CALLBACK(_read) \
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devcb = &i8212_device::set_md_rd_callback(*device, DEVCB_##_read);
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///*************************************************************************
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@ -52,6 +55,12 @@
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class i8212_device : public device_t
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{
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enum class mode : u8
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{
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INPUT,
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OUTPUT
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};
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public:
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// construction/destruction
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i8212_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
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@ -59,12 +68,19 @@ public:
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template <class Object> static devcb_base &set_int_wr_callback(device_t &device, Object &&cb) { return downcast<i8212_device &>(device).m_write_int.set_callback(std::forward<Object>(cb)); }
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template <class Object> static devcb_base &set_di_rd_callback(device_t &device, Object &&cb) { return downcast<i8212_device &>(device).m_read_di.set_callback(std::forward<Object>(cb)); }
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template <class Object> static devcb_base &set_do_wr_callback(device_t &device, Object &&cb) { return downcast<i8212_device &>(device).m_write_do.set_callback(std::forward<Object>(cb)); }
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template <class Object> static devcb_base &set_md_rd_callback(device_t &device, Object &&cb) { return downcast<i8212_device &>(device).m_read_md.set_callback(std::forward<Object>(cb)); }
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DECLARE_READ8_MEMBER( read );
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DECLARE_WRITE8_MEMBER( write );
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// data read handlers
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DECLARE_READ8_MEMBER(read);
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IRQ_CALLBACK_MEMBER(inta_cb);
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DECLARE_WRITE_LINE_MEMBER( md_w );
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DECLARE_WRITE_LINE_MEMBER( stb_w );
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// data write handlers
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DECLARE_WRITE8_MEMBER(write);
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DECLARE_WRITE8_MEMBER(strobe);
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// line write handlers
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DECLARE_WRITE_LINE_MEMBER(md_w);
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DECLARE_WRITE_LINE_MEMBER(stb_w);
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protected:
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// device-level overrides
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@ -72,19 +88,16 @@ protected:
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virtual void device_reset() override;
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private:
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enum
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{
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MODE_INPUT = 0,
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MODE_OUTPUT
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};
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// helpers
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mode get_mode();
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devcb_write_line m_write_int;
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devcb_read8 m_read_di;
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devcb_write8 m_write_do;
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devcb_read_line m_read_md;
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int m_md; // mode
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int m_stb; // strobe
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uint8_t m_data; // data latch
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uint8_t m_data; // data latch
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};
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@ -11,7 +11,7 @@
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#include "emu.h"
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#include "cpu/i8085/i8085.h"
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#include "cpu/mcs48/mcs48.h"
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#include "machine/gen_latch.h"
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#include "machine/i8212.h"
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#include "sound/ay8910.h"
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#include "speaker.h"
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@ -45,7 +45,7 @@ private:
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required_device<cpu_device> m_maincpu;
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required_device<cpu_device> m_soundcpu;
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required_device_array<ay8910_device, 2> m_psg;
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required_device_array<generic_latch_8_device, 2> m_soundlatch;
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required_device_array<i8212_device, 2> m_soundlatch;
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u8 m_port1_data;
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bool m_pcs[2];
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@ -54,7 +54,7 @@ private:
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static ADDRESS_MAP_START(main_map, AS_PROGRAM, 8, supstarf_state)
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AM_RANGE(0x0000, 0x3fff) AM_ROM
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AM_RANGE(0x8000, 0x8000) AM_DEVREAD("soundlatch1", generic_latch_8_device, read) AM_DEVWRITE("soundlatch2", generic_latch_8_device, write)
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AM_RANGE(0x8000, 0x8000) AM_DEVREAD("soundlatch1", i8212_device, read) AM_DEVWRITE("soundlatch2", i8212_device, strobe)
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AM_RANGE(0xc000, 0xc7ff) AM_RAM // 5517 (2Kx8) at IC11
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ADDRESS_MAP_END
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@ -102,7 +102,7 @@ WRITE8_MEMBER(supstarf_state::psg_latch_w)
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}
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if (m_latch_select)
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m_soundlatch[0]->write(space, 0, data);
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m_soundlatch[0]->strobe(space, 0, data);
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}
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WRITE8_MEMBER(supstarf_state::port1_w)
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@ -177,11 +177,13 @@ static MACHINE_CONFIG_START(supstarf)
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MCFG_MCS48_PORT_P2_OUT_CB(WRITE8(supstarf_state, port2_w))
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MCFG_MCS48_PORT_T1_IN_CB(READLINE(supstarf_state, phase_detect_r))
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MCFG_GENERIC_LATCH_8_ADD("soundlatch1")
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MCFG_GENERIC_LATCH_DATA_PENDING_CB(INPUTLINE("maincpu", I8085_RST55_LINE))
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MCFG_DEVICE_ADD("soundlatch1", I8212, 0)
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MCFG_I8212_MD_CALLBACK(GND)
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MCFG_I8212_INT_CALLBACK(INPUTLINE("maincpu", I8085_RST55_LINE))
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MCFG_GENERIC_LATCH_8_ADD("soundlatch2")
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MCFG_GENERIC_LATCH_DATA_PENDING_CB(INPUTLINE("soundcpu", MCS48_INPUT_IRQ))
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MCFG_DEVICE_ADD("soundlatch2", I8212, 0)
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MCFG_I8212_MD_CALLBACK(GND)
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MCFG_I8212_INT_CALLBACK(INPUTLINE("soundcpu", MCS48_INPUT_IRQ))
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//MCFG_DEVCB_CHAIN_OUTPUT(INPUTLINE("maincpu", I8085_READY_LINE))
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MCFG_SPEAKER_STANDARD_MONO("mono")
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