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author AJR <ajrhacker@users.noreply.github.com>2017-09-25 19:29:14 -0400
committer AJR <ajrhacker@users.noreply.github.com>2017-09-25 19:33:55 -0400
commit2ad6b11191b86ef86e4f64caa59619fb5cfdc692 (patch)
treedc41d72b20721aae5af30e4166ee801312b2c99e
parent51dfc76af82e9462410fb3b94d5d24addbda6c7d (diff)
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.
-rw-r--r--src/devices/machine/i8212.cpp129
-rw-r--r--src/devices/machine/i8212.h41
-rw-r--r--src/mame/drivers/supstarf.cpp18
3 files changed, 137 insertions, 51 deletions
diff --git a/src/devices/machine/i8212.cpp b/src/devices/machine/i8212.cpp
index c08ee3ad6e0..4c7cd115c75 100644
--- a/src/devices/machine/i8212.cpp
+++ b/src/devices/machine/i8212.cpp
@@ -1,8 +1,40 @@
// license:BSD-3-Clause
-// copyright-holders:Curt Coder
+// copyright-holders:Curt Coder,AJR
/**********************************************************************
- Intel 8212 8-Bit Input/Output Port emulation
+ Intel 8212/3212 8-Bit Input/Output Port (Multi-Mode Latch Buffer)
+
+ The Intel 8212 was one of the first in a line of bipolar Schottky
+ peripherals released early on for the 8080. Many of these were
+ assigned alternate part numbers in the 3200 series to identify
+ them with Intel's 3001/3002 bipolar bit-slice processing elements.
+
+ The 8212's MD pin is typically tied to either GND or Vcc to fix
+ the chip in one of its two operating modes. In the input mode
+ (MD = L), data is latched on the falling edge of STB, and the
+ three-state outputs are enabled by a combination of two chip
+ select inputs of opposite polarities. In the output mode (MD = H),
+ data is latched on the falling edge of chip selection, and outputs
+ are always enabled. The service request flip-flop is clocked on
+ the falling edge of STB to produce the INT output, and is reset by
+ either chip selection or the active-low CLR input, the latter
+ also resetting the latched data to zero.
+
+ The 8212 in output mode was often used with the 8080 to latch the
+ status word and with the 8085 to latch the lower address bits.
+
+ RCA's CDP1852 is an almost pin-for-pin CMOS counterpart to the
+ 8212. The control lines of the CDP1852, however, work slightly
+ differently, especially in output mode.
+
+ When TI second-sourced the 8080A, they cloned the 8212 as the
+ SN74S412 (and numbered their versions of the 8224, 8228 and 8338
+ similarly). While simpler octal latches from the 7400 series such
+ as 74LS273, 74LS373 and 74LS374 became far more common and widely
+ used, even when a separate service request flip-flop needed to be
+ coupled, the Fairchild Advanced Schottky TTL (FAST) evolution of
+ the 7400 series had both inverting (74F432) and non-inverting
+ (74F412) versions of this device.
**********************************************************************/
@@ -19,7 +51,7 @@
//**************************************************************************
// device type definition
-DEFINE_DEVICE_TYPE(I8212, i8212_device, "i8212", "Intel 8212 I/O")
+DEFINE_DEVICE_TYPE(I8212, i8212_device, "i8212", "Intel 8212 I/O Port")
//-------------------------------------------------
// i8212_device - constructor
@@ -30,8 +62,8 @@ i8212_device::i8212_device(const machine_config &mconfig, const char *tag, devic
m_write_int(*this),
m_read_di(*this),
m_write_do(*this),
- m_md(MODE_INPUT),
- m_stb(0), m_data(0)
+ m_read_md(*this),
+ m_stb(1), m_data(0)
{
}
@@ -46,23 +78,37 @@ void i8212_device::device_start()
m_write_int.resolve_safe();
m_read_di.resolve_safe(0);
m_write_do.resolve_safe();
+ m_read_md.resolve_safe(0);
// register for state saving
- save_item(NAME(m_md));
save_item(NAME(m_stb));
save_item(NAME(m_data));
}
//-------------------------------------------------
+// get_mode - resolve device mode
+//-------------------------------------------------
+
+i8212_device::mode i8212_device::get_mode()
+{
+ return m_read_md() ? mode::OUTPUT : mode::INPUT;
+}
+
+
+//-------------------------------------------------
// device_reset - device-specific reset
//-------------------------------------------------
void i8212_device::device_reset()
{
+ // clear interrupt line
+ m_write_int(CLEAR_LINE);
+
+ // clear latched data
m_data = 0;
- if (m_md == MODE_OUTPUT)
+ if (get_mode() == mode::OUTPUT)
{
// output data
m_write_do((offs_t)0, m_data);
@@ -74,13 +120,28 @@ void i8212_device::device_reset()
// read - data latch read
//-------------------------------------------------
-READ8_MEMBER( i8212_device::read )
+READ8_MEMBER(i8212_device::read)
+{
+ if (!machine().side_effect_disabled())
+ {
+ // clear interrupt line
+ m_write_int(CLEAR_LINE);
+ }
+
+ return m_data;
+}
+
+
+//-------------------------------------------------
+// inta_cb - data latch read (INTA triggered)
+//-------------------------------------------------
+
+IRQ_CALLBACK_MEMBER(i8212_device::inta_cb)
{
// clear interrupt line
m_write_int(CLEAR_LINE);
- LOG("I8212 INT: %u\n", CLEAR_LINE);
-
+ // read latched data as interrupt vector
return m_data;
}
@@ -89,25 +150,37 @@ READ8_MEMBER( i8212_device::read )
// write - data latch write
//-------------------------------------------------
-WRITE8_MEMBER( i8212_device::write )
+WRITE8_MEMBER(i8212_device::write)
{
- // latch data
- m_data = data;
+ // clear interrupt line
+ m_write_int(CLEAR_LINE);
+
+ if (get_mode() == mode::OUTPUT)
+ {
+ // latch data
+ m_data = data;
+ LOG("I8212: Writing %02X into latch (output mode)\n", data);
- // output data
- m_write_do((offs_t)0, m_data);
+ // output data
+ m_write_do((offs_t)0, m_data);
+ }
}
//-------------------------------------------------
-// md_w - mode write
+// strobe - data input strobe
//-------------------------------------------------
-WRITE_LINE_MEMBER( i8212_device::md_w )
+WRITE8_MEMBER(i8212_device::strobe)
{
- LOG("I8212 Mode: %s\n", state ? "output" : "input");
+ if (get_mode() == mode::INPUT)
+ {
+ m_data = data;
+ LOG("I8212: Writing %02X into latch (input mode)\n", data);
+ }
- m_md = state;
+ // assert interrupt line
+ m_write_int(ASSERT_LINE);
}
@@ -115,22 +188,20 @@ WRITE_LINE_MEMBER( i8212_device::md_w )
// stb_w - data strobe write
//-------------------------------------------------
-WRITE_LINE_MEMBER( i8212_device::stb_w )
+WRITE_LINE_MEMBER(i8212_device::stb_w)
{
- LOG("I8212 STB: %u\n", state);
-
- if (m_md == MODE_INPUT)
+ // active on falling edge
+ if (m_stb && !state)
{
- if (m_stb && !state)
+ if (get_mode() == mode::INPUT)
{
// input data
m_data = m_read_di(0);
-
- // assert interrupt line
- m_write_int(ASSERT_LINE);
-
- LOG("I8212 INT: %u\n", ASSERT_LINE);
+ LOG("I8212: Reading %02X into latch (input mode)\n", m_data);
}
+
+ // assert interrupt line
+ m_write_int(ASSERT_LINE);
}
m_stb = state;
diff --git a/src/devices/machine/i8212.h b/src/devices/machine/i8212.h
index 30bbf4b2d6a..4f871420128 100644
--- a/src/devices/machine/i8212.h
+++ b/src/devices/machine/i8212.h
@@ -1,8 +1,8 @@
// license:BSD-3-Clause
-// copyright-holders:Curt Coder
+// copyright-holders:Curt Coder,AJR
/**********************************************************************
- Intel 8212 8-Bit Input/Output Port emulation
+ Intel 8212/3212 8-Bit Input/Output Port (Multi-Mode Latch Buffer)
**********************************************************************
_____ _____
@@ -12,7 +12,7 @@
DO1 4 | | 21 DO8
DI2 5 | | 20 DI7
DO2 6 | 8212 | 19 DO7
- DI3 7 | | 18 DI6
+ DI3 7 | 3212 | 18 DI6
DO3 8 | | 17 DO6
DI4 9 | | 16 DI5
DO4 10 | | 15 DO5
@@ -42,6 +42,9 @@
#define MCFG_I8212_DO_CALLBACK(_write) \
devcb = &i8212_device::set_do_wr_callback(*device, DEVCB_##_write);
+#define MCFG_I8212_MD_CALLBACK(_read) \
+ devcb = &i8212_device::set_md_rd_callback(*device, DEVCB_##_read);
+
///*************************************************************************
@@ -52,6 +55,12 @@
class i8212_device : public device_t
{
+ enum class mode : u8
+ {
+ INPUT,
+ OUTPUT
+ };
+
public:
// construction/destruction
i8212_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
@@ -59,12 +68,19 @@ public:
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)); }
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)); }
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)); }
+ 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)); }
- DECLARE_READ8_MEMBER( read );
- DECLARE_WRITE8_MEMBER( write );
+ // data read handlers
+ DECLARE_READ8_MEMBER(read);
+ IRQ_CALLBACK_MEMBER(inta_cb);
- DECLARE_WRITE_LINE_MEMBER( md_w );
- DECLARE_WRITE_LINE_MEMBER( stb_w );
+ // data write handlers
+ DECLARE_WRITE8_MEMBER(write);
+ DECLARE_WRITE8_MEMBER(strobe);
+
+ // line write handlers
+ DECLARE_WRITE_LINE_MEMBER(md_w);
+ DECLARE_WRITE_LINE_MEMBER(stb_w);
protected:
// device-level overrides
@@ -72,19 +88,16 @@ protected:
virtual void device_reset() override;
private:
- enum
- {
- MODE_INPUT = 0,
- MODE_OUTPUT
- };
+ // helpers
+ mode get_mode();
devcb_write_line m_write_int;
devcb_read8 m_read_di;
devcb_write8 m_write_do;
+ devcb_read_line m_read_md;
- int m_md; // mode
int m_stb; // strobe
- uint8_t m_data; // data latch
+ uint8_t m_data; // data latch
};
diff --git a/src/mame/drivers/supstarf.cpp b/src/mame/drivers/supstarf.cpp
index d84a99bddde..1cdf084d30b 100644
--- a/src/mame/drivers/supstarf.cpp
+++ b/src/mame/drivers/supstarf.cpp
@@ -11,7 +11,7 @@
#include "emu.h"
#include "cpu/i8085/i8085.h"
#include "cpu/mcs48/mcs48.h"
-#include "machine/gen_latch.h"
+#include "machine/i8212.h"
#include "sound/ay8910.h"
#include "speaker.h"
@@ -45,7 +45,7 @@ private:
required_device<cpu_device> m_maincpu;
required_device<cpu_device> m_soundcpu;
required_device_array<ay8910_device, 2> m_psg;
- required_device_array<generic_latch_8_device, 2> m_soundlatch;
+ required_device_array<i8212_device, 2> m_soundlatch;
u8 m_port1_data;
bool m_pcs[2];
@@ -54,7 +54,7 @@ private:
static ADDRESS_MAP_START(main_map, AS_PROGRAM, 8, supstarf_state)
AM_RANGE(0x0000, 0x3fff) AM_ROM
- AM_RANGE(0x8000, 0x8000) AM_DEVREAD("soundlatch1", generic_latch_8_device, read) AM_DEVWRITE("soundlatch2", generic_latch_8_device, write)
+ AM_RANGE(0x8000, 0x8000) AM_DEVREAD("soundlatch1", i8212_device, read) AM_DEVWRITE("soundlatch2", i8212_device, strobe)
AM_RANGE(0xc000, 0xc7ff) AM_RAM // 5517 (2Kx8) at IC11
ADDRESS_MAP_END
@@ -102,7 +102,7 @@ WRITE8_MEMBER(supstarf_state::psg_latch_w)
}
if (m_latch_select)
- m_soundlatch[0]->write(space, 0, data);
+ m_soundlatch[0]->strobe(space, 0, data);
}
WRITE8_MEMBER(supstarf_state::port1_w)
@@ -177,11 +177,13 @@ static MACHINE_CONFIG_START(supstarf)
MCFG_MCS48_PORT_P2_OUT_CB(WRITE8(supstarf_state, port2_w))
MCFG_MCS48_PORT_T1_IN_CB(READLINE(supstarf_state, phase_detect_r))
- MCFG_GENERIC_LATCH_8_ADD("soundlatch1")
- MCFG_GENERIC_LATCH_DATA_PENDING_CB(INPUTLINE("maincpu", I8085_RST55_LINE))
+ MCFG_DEVICE_ADD("soundlatch1", I8212, 0)
+ MCFG_I8212_MD_CALLBACK(GND)
+ MCFG_I8212_INT_CALLBACK(INPUTLINE("maincpu", I8085_RST55_LINE))
- MCFG_GENERIC_LATCH_8_ADD("soundlatch2")
- MCFG_GENERIC_LATCH_DATA_PENDING_CB(INPUTLINE("soundcpu", MCS48_INPUT_IRQ))
+ MCFG_DEVICE_ADD("soundlatch2", I8212, 0)
+ MCFG_I8212_MD_CALLBACK(GND)
+ MCFG_I8212_INT_CALLBACK(INPUTLINE("soundcpu", MCS48_INPUT_IRQ))
//MCFG_DEVCB_CHAIN_OUTPUT(INPUTLINE("maincpu", I8085_READY_LINE))
MCFG_SPEAKER_STANDARD_MONO("mono")