text: // license:BSD-3-Clause
  // copyright-holders:AJR
  /***************************************************************************
  
      Skeleton driver for Systel System 1/System 100 computer.
  
      This minimalistic luggable computer has a green-screen monitor and
      5¼-inch floppy drive (Shugart SA455) built into the unit. The detached
      keyboard may be replaced with a standard electric typewriter.
  
  ***************************************************************************/
  
  #include "emu.h"
  #include "bus/rs232/rs232.h"
  #include "cpu/z80/z80.h"
  #include "imagedev/floppy.h"
  #include "machine/clock.h"
  #include "machine/input_merger.h"
  #include "machine/i8251.h"
  #include "machine/i8257.h"
  #include "machine/wd_fdc.h"
  #include "video/i8275.h"
  #include "screen.h"
  
  class systel1_state : public driver_device
  {
  public:
  	systel1_state(const machine_config &mconfig, device_type type, const char *tag)
  		: driver_device(mconfig, type, tag)
  		, m_maincpu(*this, "maincpu")
  		, m_dmac(*this, "dmac")
  		, m_fdc(*this, "fdc")
  		, m_floppy(*this, "fdc:0")
  		, m_rom(*this, "bootrom")
  		, m_chargen(*this, "chargen")
  	{
  	}
  
  	void systel1(machine_config &config);
  
  protected:
  	virtual void machine_start() override;
  	virtual void machine_reset() override;
  
  private:
  	DECLARE_WRITE_LINE_MEMBER(hrq_w);
  	u8 memory_r(offs_t offset);
  	void memory_w(offs_t offset, u8 data);
  	void floppy_control_w(u8 data);
  	DECLARE_WRITE_LINE_MEMBER(rts_w);
  	DECLARE_WRITE_LINE_MEMBER(dtr_w);
  
  	I8275_DRAW_CHARACTER_MEMBER(draw_character);
  
  	void mem_map(address_map &map);
  	void io_map(address_map &map);
  
  	required_device<cpu_device> m_maincpu;
  	required_device<i8257_device> m_dmac;
  	required_device<fd1797_device> m_fdc;
  	required_device<floppy_connector> m_floppy;
  	required_region_ptr<u8> m_rom;
  	required_region_ptr<u8> m_chargen;
  
  	std::unique_ptr<u8[]> m_ram;
  
  	bool m_boot_read;
  };
  
  void systel1_state::machine_start()
  {
  	m_ram = make_unique_clear<u8[]>(0x10000);
  	m_fdc->set_floppy(m_floppy->get_device());
  
  	save_item(NAME(m_boot_read));
  	save_pointer(NAME(m_ram), 0x10000);
  }
  
  void systel1_state::machine_reset()
  {
  	m_boot_read = true;
  }
  
  WRITE_LINE_MEMBER(systel1_state::hrq_w)
  {
  	m_maincpu->set_input_line(INPUT_LINE_HALT, state);
  	m_dmac->hlda_w(state);
  }
  
  u8 systel1_state::memory_r(offs_t offset)
  {
  	if (m_boot_read && offset < 0x4000)
  		return m_rom[offset & 0x7ff];
  	else
  		return m_ram[offset];
  }
  
  void systel1_state::memory_w(offs_t offset, u8 data)
  {
  	m_ram[offset] = data;
  }
  
  I8275_DRAW_CHARACTER_MEMBER(systel1_state::draw_character)
  {
  	u8 dots = lten ? 0xff : vsp ? 0 : m_chargen[(charcode << 4) | linecount];
  	if (rvv)
  		dots ^= 0xff;
  
  	for (int i = 0; i < 7; i++)
  	{
  		bitmap.pix(y, x + i) = BIT(dots, 7) ? rgb_t::white() : rgb_t::black();
  		dots <<= 1;
  	}
  }
  
  void systel1_state::floppy_control_w(u8 data)
  {
  	if (m_floppy->get_device() != nullptr)
  		m_floppy->get_device()->ss_w(!BIT(data, 0));
  
  	m_boot_read = false;
  }
  
  WRITE_LINE_MEMBER(systel1_state::rts_w)
  {
  	m_fdc->mr_w(state);
  	if (m_floppy->get_device() != nullptr)
  		m_floppy->get_device()->mon_w(!state);
  }
  
  WRITE_LINE_MEMBER(systel1_state::dtr_w)
  {
  	// probably floppy-related
  }
  
  void systel1_state::mem_map(address_map &map)
  {
  	map(0x0000, 0xffff).rw(FUNC(systel1_state::memory_r), FUNC(systel1_state::memory_w));
  }
  
  void systel1_state::io_map(address_map &map)
  {
  	map.global_mask(0xff);
  	map(0x00, 0x00).portr("JUMPERS");
  	map(0x10, 0x11).rw("usart", FUNC(i8251_device::read), FUNC(i8251_device::write));
  	map(0x20, 0x29).rw(m_dmac, FUNC(i8257_device::read), FUNC(i8257_device::write));
  	map(0x30, 0x33).rw(m_fdc, FUNC(fd1797_device::read), FUNC(fd1797_device::write));
  	map(0x40, 0x41).rw("crtc", FUNC(i8276_device::read), FUNC(i8276_device::write));
  	map(0x70, 0x70).w(FUNC(systel1_state::floppy_control_w));
  }
  
  static INPUT_PORTS_START(systel1)
  	PORT_START("JUMPERS")
  	PORT_DIPNAME(0x01, 0x00, "System Mode") // TYPE/WP switch on the front of the unit
  	PORT_DIPSETTING(0x01, "Typewriter")
  	PORT_DIPSETTING(0x00, "Word Processor")
  	PORT_DIPNAME(0x02, 0x00, "Screen Refresh") // probably at J6
  	PORT_DIPSETTING(0x02, "50 Hz")
  	PORT_DIPSETTING(0x00, "60 Hz")
  INPUT_PORTS_END
  
  static void systel1_floppies(device_slot_interface &device)
  {
  	device.option_add("525dd", FLOPPY_525_DD);
  }
  
  static DEVICE_INPUT_DEFAULTS_START(keyboard)
  	DEVICE_INPUT_DEFAULTS("RS232_TXBAUD", 0xff, RS232_BAUD_1200)
  DEVICE_INPUT_DEFAULTS_END
  
  void systel1_state::systel1(machine_config &config)
  {
  	Z80(config, m_maincpu, 10.8864_MHz_XTAL / 4); // Z8400A; clock verified
  	m_maincpu->set_addrmap(AS_PROGRAM, &systel1_state::mem_map);
  	m_maincpu->set_addrmap(AS_IO, &systel1_state::io_map);
  
  	input_merger_device &mainint(INPUT_MERGER_ANY_HIGH(config, "mainint"));
  	mainint.output_handler().set_inputline(m_maincpu, INPUT_LINE_IRQ0);
  
  	I8257(config, m_dmac, 10.8864_MHz_XTAL / 4); // P8257-5
  	m_dmac->out_hrq_cb().set(FUNC(systel1_state::hrq_w));
  	m_dmac->in_memr_cb().set(FUNC(systel1_state::memory_r));
  	m_dmac->out_memw_cb().set(FUNC(systel1_state::memory_w));
  	m_dmac->in_ior_cb<1>().set(m_fdc, FUNC(fd1797_device::data_r));
  	m_dmac->out_iow_cb<1>().set(m_fdc, FUNC(fd1797_device::data_w));
  	m_dmac->out_iow_cb<2>().set("crtc", FUNC(i8276_device::dack_w));
  
  	i8251_device &usart(I8251(config, "usart", 10.8864_MHz_XTAL / 4)); // AMD P8251A
  	usart.rxrdy_handler().set("mainint", FUNC(input_merger_device::in_w<0>));
  	usart.rts_handler().set(FUNC(systel1_state::rts_w));
  	usart.dtr_handler().set(FUNC(systel1_state::dtr_w));
  
  	clock_device &baudclock(CLOCK(config, "baudclock", 2_MHz_XTAL / 104)); // 19.23 kHz verified; rate probably fixed
  	baudclock.signal_handler().set("usart", FUNC(i8251_device::write_rxc));
  	baudclock.signal_handler().append("usart", FUNC(i8251_device::write_txc));
  
  	screen_device &screen(SCREEN(config, "screen", SCREEN_TYPE_RASTER));
  	screen.set_color(rgb_t::green());
  	screen.set_raw(10.8864_MHz_XTAL, 672, 0, 560, 270, 0, 250);
  	screen.set_screen_update("crtc", FUNC(i8276_device::screen_update));
  
  	i8276_device &crtc(I8276(config, "crtc", 10.8864_MHz_XTAL / 7)); // WD8276PL-00
  	crtc.set_screen("screen");
  	crtc.set_character_width(7);
  	crtc.set_display_callback(FUNC(systel1_state::draw_character));
  	crtc.drq_wr_callback().set(m_dmac, FUNC(i8257_device::dreq2_w));
  	crtc.irq_wr_callback().set("mainint", FUNC(input_merger_device::in_w<1>));
  
  	FD1797(config, m_fdc, 2_MHz_XTAL / 2);
  	m_fdc->drq_wr_callback().set(m_dmac, FUNC(i8257_device::dreq1_w));
  
  	FLOPPY_CONNECTOR(config, m_floppy, systel1_floppies, "525dd", floppy_image_device::default_mfm_floppy_formats);
  	m_floppy->set_fixed(true);
  	m_floppy->enable_sound(true);
  
  	rs232_port_device &kb(RS232_PORT(config, "kb", default_rs232_devices, "keyboard"));
  	kb.set_option_device_input_defaults("keyboard", DEVICE_INPUT_DEFAULTS_NAME(keyboard));
  	kb.rxd_handler().set("usart", FUNC(i8251_device::write_rxd));
  }
  
  // RAM: 8x MCM6665AP20
  // XTALs: 10.8864 (Y1), 2.000 (Y2)
  // Silkscreened on PCB: "SYSTEL / SYSTEM 1 / 1031-3101-00 REV H"
  ROM_START(systel100)
  	ROM_REGION(0x800, "bootrom", 0) // TMS2716JL-45
  	ROM_LOAD("u11.bin", 0x000, 0x800, CRC(29f1414a) SHA1(c87adfaaec45d0e5f4cf5946d2f04de0332b3413))
  
  	ROM_REGION(0x800, "chargen", 0) // TMS2516JL-45
  	ROM_LOAD("u16.bin", 0x000, 0x800, CRC(61a8d742) SHA1(69dada638a17353f91bff34a1e2319a35d8a3ebf))
  ROM_END
  
  COMP(198?, systel100, 0, 0, systel1, systel1, systel1_state, empty_init, "Systel Computers", "System 100", MACHINE_IS_SKELETON)
  