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-rw-r--r--src/mame/netronics/elf.cpp258
-rw-r--r--src/mame/netronics/elf.h75
-rw-r--r--src/mame/netronics/exp85.cpp391
3 files changed, 724 insertions, 0 deletions
diff --git a/src/mame/netronics/elf.cpp b/src/mame/netronics/elf.cpp
new file mode 100644
index 00000000000..7e1f3c8972c
--- /dev/null
+++ b/src/mame/netronics/elf.cpp
@@ -0,0 +1,258 @@
+// license:BSD-3-Clause
+// copyright-holders:Curt Coder
+/***************************************************************************
+
+ Netronics Elf II
+
+****************************************************************************/
+
+/*
+
+ TODO:
+ - add cassette I/O
+
+*/
+
+#include "emu.h"
+#include "elf.h"
+#include "screen.h"
+#include "speaker.h"
+#include "elf2.lh"
+
+#define LOAD \
+ BIT(m_special->read(), 1)
+
+#define MEMORY_PROTECT \
+ BIT(m_special->read(), 2)
+
+/* Read/Write Handlers */
+
+uint8_t elf2_state::dispon_r()
+{
+ m_vdc->disp_on_w(1);
+ m_vdc->disp_on_w(0);
+
+ return 0xff;
+}
+
+uint8_t elf2_state::data_r()
+{
+ return m_data;
+}
+
+void elf2_state::data_w(uint8_t data)
+{
+ m_led_l->a_w(data & 0x0f);
+ m_led_h->a_w(data >> 4);
+}
+
+void elf2_state::memory_w(offs_t offset, uint8_t data)
+{
+ if (LOAD)
+ {
+ if (MEMORY_PROTECT)
+ {
+ /* latch data from memory */
+ data = m_ram->pointer()[offset];
+ }
+ else
+ {
+ /* write latched data to memory */
+ m_ram->pointer()[offset] = data;
+ }
+
+ /* write data to 7 segment displays */
+ m_led_l->a_w(data & 0x0f);
+ m_led_h->a_w(data >> 4);
+ }
+}
+
+/* Memory Maps */
+
+void elf2_state::elf2_mem(address_map &map)
+{
+ map.unmap_value_high();
+ map.global_mask(0xff);
+ // Ram is added dynamically
+}
+
+void elf2_state::elf2_io(address_map &map)
+{
+ map.unmap_value_high();
+ map(0x01, 0x01).r(FUNC(elf2_state::dispon_r));
+ map(0x04, 0x04).rw(FUNC(elf2_state::data_r), FUNC(elf2_state::data_w));
+}
+
+/* Input Ports */
+
+INPUT_CHANGED_MEMBER(elf2_state::load_w)
+{
+ /* DMAIN is reset while LOAD is off */
+ if (!newval)
+ m_dmain = 0;
+}
+
+INPUT_CHANGED_MEMBER(elf2_state::input_w)
+{
+ /* assert DMAIN */
+ if (LOAD && !newval && ~m_sc & 2)
+ m_dmain = 1;
+}
+
+static INPUT_PORTS_START( elf2 )
+ PORT_START("X1")
+ PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_0) PORT_CHAR('0')
+ PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_4) PORT_CHAR('4')
+ PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_8) PORT_CHAR('8')
+ PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_C) PORT_CHAR('C')
+ PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_UNUSED )
+
+ PORT_START("X2")
+ PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_1) PORT_CHAR('1')
+ PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_5) PORT_CHAR('5')
+ PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_9) PORT_CHAR('9')
+ PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_D) PORT_CHAR('D')
+ PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_UNUSED )
+
+ PORT_START("X3")
+ PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_2) PORT_CHAR('2')
+ PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_6) PORT_CHAR('6')
+ PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_A) PORT_CHAR('A')
+ PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_E) PORT_CHAR('E')
+ PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_UNUSED )
+
+ PORT_START("X4")
+ PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_3) PORT_CHAR('3')
+ PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_7) PORT_CHAR('7')
+ PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_B) PORT_CHAR('B')
+ PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_F) PORT_CHAR('F')
+ PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_UNUSED )
+
+ PORT_START("SPECIAL")
+ PORT_BIT( 0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD ) PORT_NAME("RUN") PORT_CODE(KEYCODE_R) PORT_TOGGLE
+ PORT_BIT( 0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD ) PORT_NAME("LOAD") PORT_CODE(KEYCODE_L) PORT_TOGGLE PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(elf2_state::load_w), 0)
+ PORT_BIT( 0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD ) PORT_NAME("MP") PORT_CODE(KEYCODE_M) PORT_TOGGLE
+ PORT_BIT( 0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD ) PORT_NAME("IN") PORT_CODE(KEYCODE_ENTER) PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(elf2_state::input_w), 0)
+INPUT_PORTS_END
+
+/* CDP1802 Configuration */
+
+void elf2_state::sc_w(uint8_t data)
+{
+ /* DMAIN is reset while SC1 is high */
+ if (data & 2)
+ m_dmain = 0;
+
+ m_sc = data;
+}
+
+/* MM74C923 Interface */
+
+void elf2_state::da_w(int state)
+{
+ if (state)
+ {
+ /* shift keyboard data to latch */
+ m_data <<= 4;
+ m_data |= m_kb->read() & 0x0f;
+
+ if (LOAD)
+ {
+ /* write data to 7 segment displays */
+ m_led_l->a_w(m_data & 0x0f);
+ m_led_h->a_w(m_data >> 4);
+ }
+ }
+}
+
+/* Machine Initialization */
+
+void elf2_state::machine_start()
+{
+ address_space &program = m_maincpu->space(AS_PROGRAM);
+
+ /* setup memory banking */
+ program.install_rom(0x0000, 0x00ff, m_ram->pointer());
+ program.install_write_handler(0x0000, 0x00ff, write8sm_delegate(*this, FUNC(elf2_state::memory_w)));
+
+ /* register for state saving */
+ save_item(NAME(m_data));
+ save_item(NAME(m_sc));
+ save_item(NAME(m_dmain));
+}
+
+/* Machine Driver */
+
+QUICKLOAD_LOAD_MEMBER(elf2_state::quickload_cb)
+{
+ int const size = image.length();
+
+ if (size > m_ram->size())
+ {
+ return std::make_pair(image_error::INVALIDLENGTH, std::string());
+ }
+
+ image.fread(m_ram->pointer(), size);
+
+ return std::make_pair(std::error_condition(), std::string());
+}
+
+void elf2_state::elf2(machine_config &config)
+{
+ /* basic machine hardware */
+ CDP1802(config, m_maincpu, XTAL(3'579'545)/2);
+ m_maincpu->set_addrmap(AS_PROGRAM, &elf2_state::elf2_mem);
+ m_maincpu->set_addrmap(AS_IO, &elf2_state::elf2_io);
+ m_maincpu->wait_cb().set_ioport("SPECIAL").bit(1).invert();
+ m_maincpu->clear_cb().set_ioport("SPECIAL").bit(0);
+ m_maincpu->dma_in_cb().set([this]() { return m_dmain; });
+ m_maincpu->ef4_cb().set_ioport("SPECIAL").bit(3);
+ m_maincpu->q_cb().set_output("led0");
+ m_maincpu->dma_rd_cb().set(FUNC(elf2_state::data_r));
+ m_maincpu->dma_wr_cb().set(m_vdc, FUNC(cdp1861_device::dma_w));
+ m_maincpu->sc_cb().set(FUNC(elf2_state::sc_w));
+
+ /* video hardware */
+ config.set_default_layout(layout_elf2);
+
+ CDP1861(config, m_vdc, XTAL(3'579'545)/2).set_screen(SCREEN_TAG);
+ m_vdc->int_cb().set_inputline(m_maincpu, COSMAC_INPUT_LINE_INT);
+ m_vdc->dma_out_cb().set_inputline(m_maincpu, COSMAC_INPUT_LINE_DMAOUT);
+ m_vdc->efx_cb().set_inputline(m_maincpu, COSMAC_INPUT_LINE_EF1);
+ SCREEN(config, SCREEN_TAG, SCREEN_TYPE_RASTER);
+
+ /* devices */
+ MM74C923(config, m_kb, 0);
+ m_kb->set_cap_osc(CAP_U(0.15));
+ m_kb->set_cap_debounce(CAP_U(1));
+ m_kb->da_wr_callback().set(FUNC(elf2_state::da_w));
+ m_kb->x1_rd_callback().set_ioport("X1");
+ m_kb->x2_rd_callback().set_ioport("X2");
+ m_kb->x3_rd_callback().set_ioport("X3");
+ m_kb->x4_rd_callback().set_ioport("X4");
+
+ DM9368(config, m_led_h).update_cb().set_output("digit0");
+ DM9368(config, m_led_l).update_cb().set_output("digit1");
+
+ SPEAKER(config, "mono").front_center();
+
+ CASSETTE(config, m_cassette);
+ m_cassette->set_default_state(CASSETTE_STOPPED | CASSETTE_MOTOR_ENABLED | CASSETTE_SPEAKER_ENABLED);
+ m_cassette->add_route(ALL_OUTPUTS, "mono", 0.05);
+
+ QUICKLOAD(config, "quickload", "bin").set_load_callback(FUNC(elf2_state::quickload_cb));
+
+ /* internal ram */
+ RAM(config, RAM_TAG).set_default_size("256");
+}
+
+/* ROMs */
+
+ROM_START( elf2 )
+ ROM_REGION( 0x10000, CDP1802_TAG, ROMREGION_ERASE00 )
+ROM_END
+
+/* System Drivers */
+
+// YEAR NAME PARENT COMPAT MACHINE INPUT CLASS INIT COMPANY FULLNAME FLAGS
+COMP( 1978, elf2, 0, 0, elf2, elf2, elf2_state, empty_init, "Netronics", "Elf II", MACHINE_SUPPORTS_SAVE | MACHINE_NO_SOUND_HW )
diff --git a/src/mame/netronics/elf.h b/src/mame/netronics/elf.h
new file mode 100644
index 00000000000..d03ccbebe9b
--- /dev/null
+++ b/src/mame/netronics/elf.h
@@ -0,0 +1,75 @@
+// license:BSD-3-Clause
+// copyright-holders:Curt Coder
+#ifndef MAME_NETRONICS_ELF_H
+#define MAME_NETRONICS_ELF_H
+
+#pragma once
+
+
+#include "cpu/cosmac/cosmac.h"
+#include "imagedev/cassette.h"
+#include "imagedev/snapquik.h"
+#include "machine/mm74c922.h"
+#include "video/cdp1861.h"
+#include "video/dm9368.h"
+#include "machine/rescap.h"
+#include "machine/ram.h"
+
+#define SCREEN_TAG "screen"
+#define CDP1802_TAG "a6"
+#define CDP1861_TAG "a14"
+#define MM74C923_TAG "a10"
+#define DM9368_L_TAG "a12"
+#define DM9368_H_TAG "a8"
+
+class elf2_state : public driver_device
+{
+public:
+ elf2_state(const machine_config &mconfig, device_type type, const char *tag)
+ : driver_device(mconfig, type, tag)
+ , m_maincpu(*this, CDP1802_TAG)
+ , m_vdc(*this, CDP1861_TAG)
+ , m_kb(*this, MM74C923_TAG)
+ , m_led_l(*this, DM9368_L_TAG)
+ , m_led_h(*this, DM9368_H_TAG)
+ , m_cassette(*this, "cassette")
+ , m_ram(*this, RAM_TAG)
+ , m_special(*this, "SPECIAL")
+ { }
+
+ void elf2(machine_config &config);
+
+ DECLARE_INPUT_CHANGED_MEMBER(load_w);
+ DECLARE_INPUT_CHANGED_MEMBER(input_w);
+
+protected:
+ virtual void machine_start() override ATTR_COLD;
+
+private:
+ uint8_t dispon_r();
+ uint8_t data_r();
+ void data_w(uint8_t data);
+ void memory_w(offs_t offset, uint8_t data);
+ void sc_w(uint8_t data);
+ void da_w(int state);
+
+ DECLARE_QUICKLOAD_LOAD_MEMBER(quickload_cb);
+ void elf2_io(address_map &map) ATTR_COLD;
+ void elf2_mem(address_map &map) ATTR_COLD;
+
+ required_device<cosmac_device> m_maincpu;
+ required_device<cdp1861_device> m_vdc;
+ required_device<mm74c922_device> m_kb;
+ required_device<dm9368_device> m_led_l;
+ required_device<dm9368_device> m_led_h;
+ required_device<cassette_image_device> m_cassette;
+ required_device<ram_device> m_ram;
+ required_ioport m_special;
+
+ // internal state
+ uint8_t m_data = 0;
+ uint8_t m_sc = 0;
+ uint8_t m_dmain = 0;
+};
+
+#endif // MAME_NETRONICS_ELF_H
diff --git a/src/mame/netronics/exp85.cpp b/src/mame/netronics/exp85.cpp
new file mode 100644
index 00000000000..2dfdd76a317
--- /dev/null
+++ b/src/mame/netronics/exp85.cpp
@@ -0,0 +1,391 @@
+// license:BSD-3-Clause
+// copyright-holders:Curt Coder
+/***************************************************************************
+
+ Explorer 85
+
+ 12/05/2009 Skeleton driver.
+ 29/12/2023 Reworked driver to enable extended RAM memory,
+ MS BASIC and disable ROM mirror after boot/interrupt.
+
+ Setting Up
+ ==========
+ The terminal must be set for
+ - Baud: 9600
+ - Format: 7E1
+ If it isn't, adjust the settings, then restart the system.
+
+ Once started, press Space. The system will start up.
+ All input must be in upper case.
+
+ Microsoft Basic is executed entering the following 2 commands
+ in the monitor prompt:
+ .XS nnnn-F87F mmmm-C000 <CR>
+ .G <CR>
+
+ where nnnn is the previous value of the stack pointer, and mmmm is the
+ previous value of the program counter.
+
+ BASIC will request the amount of RAM memory available, 8192 (bytes) must
+ be entered.
+
+
+****************************************************************************/
+
+/*
+
+ TODO:
+
+ - dump of the hexadecimal keyboard monitor ROM
+ - 64K RAM expansion
+ - Disk drive and CP/M OS support
+
+*/
+
+
+#include "emu.h"
+
+#include "machine/i8155.h"
+#include "machine/i8355.h"
+#include "machine/ram.h"
+#include "speaker.h"
+
+#include "bus/rs232/rs232.h"
+#include "cpu/i8085/i8085.h"
+#include "imagedev/cassette.h"
+#include "sound/spkrdev.h"
+
+namespace {
+
+static constexpr int LOW_MEMORY_ROM_MIRROR_ENTRY = 0;
+static constexpr int LOW_MEMORY_RAM_ENTRY = 1;
+
+class exp85_state : public driver_device
+{
+public:
+ exp85_state(const machine_config &mconfig, device_type type, const char *tag)
+ : driver_device(mconfig, type, tag)
+ , m_maincpu(*this, "u100")
+ , m_i8355(*this, "u105")
+ , m_i8155(*this, "u106")
+ , m_rs232(*this, "rs232")
+ , m_cassette(*this, "cassette")
+ , m_speaker(*this, "speaker")
+ , m_rom(*this, "u105") // the 8355 chip contains the monitor ROM
+ , m_low_memory_view(*this, "low_memory_view")
+ , m_is_preparing_interrupt_call(false)
+ , m_ignore_timer_out(true)
+ , m_tape_control(0)
+ , m_timer(nullptr)
+ { }
+
+ void exp85(machine_config &config);
+
+ DECLARE_INPUT_CHANGED_MEMBER( trigger_reset );
+ DECLARE_INPUT_CHANGED_MEMBER( trigger_rst75 );
+
+private:
+ virtual void machine_start() override ATTR_COLD;
+
+ uint8_t i8355_a_r();
+ void i8355_a_w(uint8_t data);
+ int sid_r();
+ void sod_w(int state);
+
+ void status_out(u8 status);
+
+ void exp85_io(address_map &map) ATTR_COLD;
+ void exp85_mem(address_map &map) ATTR_COLD;
+
+ void to_change(int to);
+
+ TIMER_CALLBACK_MEMBER(trap_delay);
+
+ // Member variables
+ required_device<i8085a_cpu_device> m_maincpu;
+ required_device<i8355_device> m_i8355;
+ required_device<i8155_device> m_i8155;
+ required_device<rs232_port_device> m_rs232;
+ required_device<cassette_image_device> m_cassette;
+ required_device<speaker_sound_device> m_speaker;
+ required_memory_region m_rom;
+ memory_view m_low_memory_view;
+
+ bool m_is_preparing_interrupt_call;
+ bool m_ignore_timer_out;
+ bool m_tape_control;
+ emu_timer *m_timer;
+};
+
+
+/* Memory Maps */
+void exp85_state::exp85_mem(address_map &map)
+{
+ map.unmap_value_high();
+ // Extended RAM or mapped monitor ROM (only during interrupt and reset)
+ map(0x0000, 0x1fff).view(m_low_memory_view);
+ // Microsoft BASIC ROM
+ map(0xc000, 0xdfff).rom();
+ // Monitor ROM in the 8355 chip
+ map(0xf000, 0xf7ff).rom().region(m_rom, 0);
+ // 256 bytes of RAM of level A in the 8155 chip.
+ map(0xf800, 0xf8ff).rw(m_i8155, FUNC(i8155_device::memory_r), FUNC(i8155_device::memory_w));
+
+ // monitor ROM mirror
+ m_low_memory_view[LOW_MEMORY_ROM_MIRROR_ENTRY](0x0000, 0x07ff).rom().region(m_rom, 0);
+ // extended RAM
+ m_low_memory_view[LOW_MEMORY_RAM_ENTRY](0x0000, 0x1fff).ram();
+}
+
+void exp85_state::exp85_io(address_map &map)
+{
+ map.unmap_value_high();
+ map.global_mask(0xff);
+ map(0xf0, 0xf3).rw(m_i8355, FUNC(i8355_device::io_r), FUNC(i8355_device::io_w));
+ map(0xf8, 0xfd).rw(m_i8155, FUNC(i8155_device::io_r), FUNC(i8155_device::io_w));
+}
+
+/* Input Ports */
+
+INPUT_CHANGED_MEMBER( exp85_state::trigger_reset )
+{
+ m_maincpu->set_input_line(INPUT_LINE_RESET, newval ? CLEAR_LINE : ASSERT_LINE);
+ m_low_memory_view.select(LOW_MEMORY_ROM_MIRROR_ENTRY);
+}
+
+INPUT_CHANGED_MEMBER( exp85_state::trigger_rst75 )
+{
+ m_maincpu->set_input_line(I8085_RST75_LINE, newval ? CLEAR_LINE : ASSERT_LINE);
+}
+
+static INPUT_PORTS_START( exp85 )
+ PORT_START("SPECIAL")
+ PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYPAD ) PORT_NAME("R") PORT_CODE(KEYCODE_F1) PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(exp85_state::trigger_reset), 0)
+ PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYPAD ) PORT_NAME("I") PORT_CODE(KEYCODE_F2) PORT_CHANGED_MEMBER(DEVICE_SELF, FUNC(exp85_state::trigger_rst75), 0)
+INPUT_PORTS_END
+
+/* 8355 Interface */
+
+uint8_t exp85_state::i8355_a_r()
+{
+ /*
+
+ bit description
+
+ PA0 tape control
+ PA1 jumper S17 (open=+5V closed=GND)
+ PA2 J5:13
+ PA3
+ PA4 J2:22
+ PA5
+ PA6
+ PA7 speaker output
+
+ */
+
+ return 0x02;
+}
+
+void exp85_state::i8355_a_w(uint8_t data)
+{
+ /*
+
+ bit description
+
+ PA0 tape control
+ PA1 jumper S17 (open=+5V closed=GND)
+ PA2 J5:13
+ PA3
+ PA4 J2:22
+ PA5
+ PA6
+ PA7 speaker output
+
+ */
+
+ /* tape control */
+ m_tape_control = BIT(data, 0);
+
+ /* speaker output */
+ m_speaker->level_w(!BIT(data, 7));
+}
+
+/* I8085A Interface */
+
+int exp85_state::sid_r()
+{
+ int data = 1;
+
+ if (m_tape_control)
+ {
+ data = (m_cassette->input() > +0.0);
+ }
+ else
+ {
+ data = m_rs232->rxd_r();
+ }
+
+ return data;
+}
+
+void exp85_state::sod_w(int state)
+{
+ if (m_tape_control)
+ {
+ m_cassette->output(state ? -1.0 : +1.0);
+ }
+ else
+ {
+ m_rs232->write_txd(state);
+ }
+}
+
+/* Memory mapping mgmt during reset and interrupt */
+
+void exp85_state::status_out(u8 status)
+{
+ // In the real hardware this is monitored via the IO/M, S0, S1
+ // and ALE output pins of the 8085.
+ // Since these pins are not emulated, then we must explicitly get the internal
+ // interrupt acknowledge state (0x23 or 0x26) and behave as the monitor expects.
+ auto current_pc = m_maincpu->pc();
+ if (status == 0x23 || status == 0x26)
+ {
+ // When an interrupt is triggered the low memory shall be set to the ROM mirror
+ m_is_preparing_interrupt_call = true;
+ m_low_memory_view.select(LOW_MEMORY_ROM_MIRROR_ENTRY);
+ }
+ else if (m_is_preparing_interrupt_call && (current_pc & 0xff00) == 0x0000)
+ {
+ // Avoids setting the lower memory back to RAM until
+ // it branches to the interrupt handler.
+ m_is_preparing_interrupt_call = false;
+ }
+ else if (!m_is_preparing_interrupt_call && (current_pc & 0xf000) == 0xf000)
+ {
+ // When the interrupt handler is executing and the address is >= 0xf000
+ // the low memory is mapped to RAM
+ m_low_memory_view.select(LOW_MEMORY_RAM_ENTRY);
+ }
+
+}
+
+//**************************************************************************
+// INPUT PORTS
+//**************************************************************************
+
+
+/* Terminal Interface */
+
+static DEVICE_INPUT_DEFAULTS_START( terminal )
+ DEVICE_INPUT_DEFAULTS( "RS232_TXBAUD", 0xff, RS232_BAUD_9600 )
+ DEVICE_INPUT_DEFAULTS( "RS232_RXBAUD", 0xff, RS232_BAUD_9600 )
+ DEVICE_INPUT_DEFAULTS( "RS232_DATABITS", 0xff, RS232_DATABITS_7 )
+ DEVICE_INPUT_DEFAULTS( "RS232_PARITY", 0xff, RS232_PARITY_EVEN )
+ DEVICE_INPUT_DEFAULTS( "RS232_STOPBITS", 0xff, RS232_STOPBITS_1 )
+DEVICE_INPUT_DEFAULTS_END
+
+/* Machine Initialization */
+
+void exp85_state::machine_start()
+{
+ /* clear the trap line that is asserted on start */
+ m_maincpu->set_input_line(I8085_TRAP_LINE, CLEAR_LINE);
+
+ /* setup memory mirror switch */
+ m_low_memory_view.select(LOW_MEMORY_ROM_MIRROR_ENTRY);
+
+ save_item(NAME(m_tape_control));
+
+ m_timer = timer_alloc(FUNC(exp85_state::trap_delay), this);
+}
+
+void exp85_state::to_change(int to)
+{
+ // In the 8155 implementation the TIMER-OUT line (to) is
+ // asserted by default on initialization; this generates a spurious exception
+ // avoided here via an ignore flag.
+ if (m_ignore_timer_out)
+ {
+ m_ignore_timer_out = false;
+ return;
+ }
+
+ // The 8155 has a max TIMER-IN to TIMER-OUT delay of 400ns (datasheet page 3-256). In a real system
+ // this delay was measured in ~70ns. This is enough for the next instruction cycle to start
+ // and for the interrupt to be acknowledged one instruction later. This effect is fundamental
+ // for the ROM monitor stepping functionality, since it depends heavily on interrupting when the
+ // next instruction of the user program is being executed.
+ // MAME allows to set a timer of 70ns but that is not enough to get the CPU scheduled for at least 1 cycle
+ // before the interrupt is serviced, so we program a timer to expire beyond a full clock cycle.
+ m_timer->adjust(m_i8155->clocks_to_attotime(2), to);
+}
+
+TIMER_CALLBACK_MEMBER(exp85_state::trap_delay)
+{
+ // The 8155 TIMER-OUT line is connected to the TRAP input line of the 8085;
+ // that line is set from the start high, and since there is no change in that line, the
+ // interrup is never requested (datasheet, page 6-13).
+ m_maincpu->set_input_line(I8085_TRAP_LINE, param == 1 ? ASSERT_LINE : CLEAR_LINE);
+}
+
+/* Machine Driver */
+void exp85_state::exp85(machine_config &config)
+{
+ /* basic machine hardware */
+ I8085A(config, m_maincpu, 6.144_MHz_XTAL);
+ m_maincpu->set_addrmap(AS_PROGRAM, &exp85_state::exp85_mem);
+ m_maincpu->set_addrmap(AS_IO, &exp85_state::exp85_io);
+ m_maincpu->in_sid_func().set(FUNC(exp85_state::sid_r));
+ m_maincpu->out_sod_func().set(FUNC(exp85_state::sod_w));
+ m_maincpu->out_status_func().set(FUNC(exp85_state::status_out));
+
+ /* sound hardware */
+ SPEAKER(config, "mono").front_center();
+ SPEAKER_SOUND(config, m_speaker).add_route(ALL_OUTPUTS, "mono", 0.25);
+
+ /* devices */
+
+ // The Explorer-85 uses a 6.144MHz clock, but the Intel 8085 divides by 2 this
+ // input frequency to give the processor internal operating frequency.
+ // The bus is connected to the CLK (out) of the 8085, running also
+ // at 6.144MHz divided by 2.
+ I8155(config, m_i8155, 6.144_MHz_XTAL/2);
+ m_i8155->out_to_callback().set(FUNC(exp85_state::to_change));
+
+
+ I8355(config, m_i8355, 6.144_MHz_XTAL/2);
+ m_i8355->in_pa().set(FUNC(exp85_state::i8355_a_r));
+ m_i8355->out_pa().set(FUNC(exp85_state::i8355_a_w));
+
+ CASSETTE(config, m_cassette);
+ m_cassette->set_default_state(CASSETTE_STOPPED | CASSETTE_MOTOR_ENABLED | CASSETTE_SPEAKER_ENABLED);
+ m_cassette->add_route(ALL_OUTPUTS, "mono", 0.05);
+
+ RS232_PORT(config, "rs232", default_rs232_devices, "terminal").set_option_device_input_defaults("terminal", DEVICE_INPUT_DEFAULTS_NAME(terminal));
+
+}
+
+/* ROMs */
+
+ROM_START( exp85 )
+ ROM_REGION( 0x10000, "u100", 0 ) // Microsoft BASIC
+ ROM_DEFAULT_BIOS("eia")
+ ROM_LOAD( "c000.bin", 0xc000, 0x0800, CRC(73ce4aad) SHA1(2c69cd0b6c4bdc92f4640bce18467e4e99255bab) )
+ ROM_LOAD( "c800.bin", 0xc800, 0x0800, CRC(eb3fdedc) SHA1(af92d07f7cb7533841b16e1176401363176857e1) )
+ ROM_LOAD( "d000.bin", 0xd000, 0x0800, CRC(c10c4a22) SHA1(30588ba0b27a775d85f8c581ad54400c8521225d) )
+ ROM_LOAD( "d800.bin", 0xd800, 0x0800, CRC(dfa43ef4) SHA1(56a7e7a64928bdd1d5f0519023d1594cacef49b3) )
+
+ ROM_REGION( 0x800, "u105", 0 ) // Explorer 85 Monitor
+ ROM_SYSTEM_BIOS( 0, "eia", "EIA Terminal" ) // Serial terminal ROM
+ ROMX_LOAD( "ex 85.u105", 0x0000, 0x0800, CRC(1a99d0d9) SHA1(57b6d48e71257bc4ef2d3dddc9b30edf6c1db766), ROM_BIOS(0) )
+ ROM_SYSTEM_BIOS( 1, "hex", "Hex Keyboard" ) // Keypad ROM (not available)
+ ROMX_LOAD( "1kbd.u105", 0x0000, 0x0800, NO_DUMP, ROM_BIOS(1) )
+ROM_END
+
+} // anonymous namespace
+
+
+/* System Drivers */
+// YEAR NAME PARENT COMPAT MACHINE INPUT CLASS INIT COMPANY FULLNAME FLAGS
+COMP( 1979, exp85, 0, 0, exp85, exp85, exp85_state, empty_init, "Netronics", "Explorer/85", MACHINE_SUPPORTS_SAVE )