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Diffstat (limited to 'src/mame/netronics/exp85.cpp')
-rw-r--r-- | src/mame/netronics/exp85.cpp | 391 |
1 files changed, 391 insertions, 0 deletions
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 ) |