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path: root/src/mame/drivers/unixpc.cpp
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// license:GPL-2.0+
// copyright-holders:Dirk Best, R. Belmont
/***************************************************************************

    AT&T Unix PC series

    Skeleton driver by Dirk Best and R. Belmont

    DIVS instruction at 0x801112 (the second time) causes a divide-by-zero
    exception the system isn't ready for due to word at 0x5EA6 being zero.

    Code might not get there if the attempted FDC boot succeeds; FDC hookup
    probably needs help.  2797 isn't asserting DRQ?

***************************************************************************/


#include "emu.h"
#include "cpu/m68000/m68000.h"
#include "machine/ram.h"
#include "machine/wd_fdc.h"
#include "machine/bankdev.h"
#include "screen.h"

#include "unixpc.lh"


/***************************************************************************
    DRIVER STATE
***************************************************************************/

class unixpc_state : public driver_device
{
public:
	unixpc_state(const machine_config &mconfig, device_type type, const char *tag) :
		driver_device(mconfig, type, tag),
		m_maincpu(*this, "maincpu"),
		m_ram(*this, RAM_TAG),
		m_wd2797(*this, "wd2797"),
		m_floppy(*this, "wd2797:0:525dd"),
		m_ramrombank(*this, "ramrombank"),
		m_mapram(*this, "mapram"),
		m_videoram(*this, "videoram")
	{ }

	void unixpc(machine_config &config);

protected:
	uint32_t screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);

	virtual void machine_start() override;
	virtual void machine_reset() override;

	DECLARE_READ16_MEMBER( line_printer_r );
	DECLARE_WRITE16_MEMBER( misc_control_w );
	DECLARE_WRITE16_MEMBER( disk_control_w );
	DECLARE_WRITE16_MEMBER( romlmap_w );
	DECLARE_WRITE16_MEMBER( error_enable_w );
	DECLARE_WRITE16_MEMBER( parity_enable_w );
	DECLARE_WRITE16_MEMBER( bpplus_w );
	DECLARE_READ16_MEMBER( ram_mmu_r );
	DECLARE_WRITE16_MEMBER( ram_mmu_w );
	DECLARE_READ16_MEMBER( rtc_r );
	DECLARE_WRITE16_MEMBER( rtc_w );
	DECLARE_READ16_MEMBER( diskdma_size_r );
	DECLARE_WRITE16_MEMBER( diskdma_size_w );
	DECLARE_WRITE16_MEMBER( diskdma_ptr_w );

	DECLARE_WRITE_LINE_MEMBER( wd2797_intrq_w );
	DECLARE_WRITE_LINE_MEMBER( wd2797_drq_w );

	void ramrombank_map(address_map &map);
	void unixpc_mem(address_map &map);

private:
	required_device<cpu_device> m_maincpu;
	required_device<ram_device> m_ram;
	required_device<wd2797_device> m_wd2797;
	required_device<floppy_image_device> m_floppy;
	required_device<address_map_bank_device> m_ramrombank;

	required_shared_ptr<uint16_t> m_mapram;
	required_shared_ptr<uint16_t> m_videoram;

	uint16_t *m_ramptr;
	uint32_t m_ramsize;
	uint16_t m_diskdmasize;
	uint32_t m_diskdmaptr;
	bool m_fdc_intrq;
};


/***************************************************************************
    MEMORY
***************************************************************************/

WRITE16_MEMBER( unixpc_state::romlmap_w )
{
	if (BIT(data, 15))
	{
		m_ramrombank->set_bank(1);
	}
	else
	{
		m_ramrombank->set_bank(0);
	}
}

READ16_MEMBER( unixpc_state::ram_mmu_r )
{
	// TODO: MMU translation
	if (offset > m_ramsize)
	{
		return 0xffff;
	}
	return m_ramptr[offset];
}

WRITE16_MEMBER( unixpc_state::ram_mmu_w )
{
	// TODO: MMU translation
	if (offset < m_ramsize)
	{
		COMBINE_DATA(&m_ramptr[offset]);
	}
}

void unixpc_state::machine_start()
{
	m_ramptr = (uint16_t *)m_ram->pointer();
	m_ramsize = m_ram->size();
}

void unixpc_state::machine_reset()
{
	// force ROM into lower mem on reset
	m_ramrombank->set_bank(0);

	// reset cpu so that it can pickup the new values
	m_maincpu->reset();
}

WRITE16_MEMBER( unixpc_state::error_enable_w )
{
	logerror("error_enable_w: %04x\n", data & 0x8000);
}

WRITE16_MEMBER( unixpc_state::parity_enable_w )
{
	logerror("parity_enable_w: %04x\n", data & 0x8000);
}

WRITE16_MEMBER( unixpc_state::bpplus_w )
{
	logerror("bpplus_w: %04x\n", data & 0x8000);
}

/***************************************************************************
    MISC
***************************************************************************/

READ16_MEMBER( unixpc_state::rtc_r )
{
	return 0;
}

WRITE16_MEMBER( unixpc_state::rtc_w )
{
	logerror("rtc_w: %04x\n", data);
}

READ16_MEMBER( unixpc_state::line_printer_r )
{
	uint16_t data = 0;

	data |= 1; // no dial tone detected
	data |= 1 << 1; // no parity error
	data |= 0 << 2; // hdc intrq
	data |= m_fdc_intrq ? 1<<3 : 0<<3;

	//logerror("line_printer_r: %04x\n", data);

	return data;
}

WRITE16_MEMBER( unixpc_state::misc_control_w )
{
	logerror("misc_control_w: %04x\n", data);

	// bit 15 = VBL ack (must go high-low-high to ack)
	// bit 14 = 0 for disk DMA write, 1 for disk DMA read
	// bit 13 = Centronics strobe
	// bit 12 = 0 = modem baud rate from UART clock inputs, 1 = baud from programmable timer

	output().set_value("led_0", !BIT(data,  8));
	output().set_value("led_1", !BIT(data,  9));
	output().set_value("led_2", !BIT(data, 10));
	output().set_value("led_3", !BIT(data, 11));
}

/***************************************************************************
    DMA
***************************************************************************/

READ16_MEMBER( unixpc_state::diskdma_size_r )
{
	return m_diskdmasize;
}

WRITE16_MEMBER( unixpc_state::diskdma_size_w )
{
	COMBINE_DATA( &m_diskdmasize );
	logerror("%x to disk DMA size\n", data);
}

WRITE16_MEMBER( unixpc_state::diskdma_ptr_w )
{
	if (offset >= 0x2000)
	{
		// set top 4 bytes
		m_diskdmaptr &= 0xff;
		m_diskdmaptr |= (offset << 8);
	}
	else
	{
		m_diskdmaptr &= 0xffff00;
		m_diskdmaptr |= (offset & 0xff);
	}

	logerror("diskdma_ptr_w: wrote at %x, ptr now %x\n", offset<<1, m_diskdmaptr);
}

/***************************************************************************
    FLOPPY
***************************************************************************/

WRITE16_MEMBER( unixpc_state::disk_control_w )
{
	logerror("disk_control_w: %04x\n", data);

	m_floppy->mon_w(!BIT(data, 5));

	// bit 6 = floppy selected / not selected
	if (BIT(data, 6))
		m_wd2797->set_floppy(m_floppy);
	else
		m_wd2797->set_floppy(nullptr);
}

WRITE_LINE_MEMBER( unixpc_state::wd2797_intrq_w )
{
	logerror("wd2797_intrq_w: %d\n", state);
	m_fdc_intrq = state;
}

WRITE_LINE_MEMBER( unixpc_state::wd2797_drq_w )
{
	logerror("wd2797_drq_w: %d\n", state);
}


/***************************************************************************
    VIDEO
***************************************************************************/

uint32_t unixpc_state::screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
	for (int y = 0; y < 348; y++)
		for (int x = 0; x < 720/16; x++)
			for (int b = 0; b < 16; b++)
				bitmap.pix16(y, x * 16 + b) = BIT(m_videoram[y * (720/16) + x], b);

	return 0;
}


/***************************************************************************
    ADDRESS MAPS
***************************************************************************/

void unixpc_state::unixpc_mem(address_map &map)
{
	map(0x000000, 0x3fffff).m(m_ramrombank, FUNC(address_map_bank_device::amap16));
	map(0x400000, 0x4007ff).ram().share("mapram");
	map(0x420000, 0x427fff).ram().share("videoram");
	map(0x460000, 0x460001).rw(FUNC(unixpc_state::diskdma_size_r), FUNC(unixpc_state::diskdma_size_w));
	map(0x470000, 0x470001).r(FUNC(unixpc_state::line_printer_r));
	map(0x480000, 0x480001).w(FUNC(unixpc_state::rtc_w));
	map(0x4a0000, 0x4a0001).w(FUNC(unixpc_state::misc_control_w));
	map(0x4d0000, 0x4d7fff).w(FUNC(unixpc_state::diskdma_ptr_w));
	map(0x4e0000, 0x4e0001).w(FUNC(unixpc_state::disk_control_w));
	map(0xe10000, 0xe10007).rw(m_wd2797, FUNC(wd_fdc_device_base::read), FUNC(wd_fdc_device_base::write)).umask16(0x00ff);
	map(0xe30000, 0xe30001).r(FUNC(unixpc_state::rtc_r));
	map(0xe40000, 0xe40001).w(FUNC(unixpc_state::error_enable_w));
	map(0xe41000, 0xe41001).w(FUNC(unixpc_state::parity_enable_w));
	map(0xe42000, 0xe42001).w(FUNC(unixpc_state::bpplus_w));
	map(0xe43000, 0xe43001).w(FUNC(unixpc_state::romlmap_w));
	map(0x800000, 0x803fff).mirror(0x7fc000).rom().region("bootrom", 0);
	// e70000 / e70002 = keyboard 6850 status/control and Rx data / Tx data
}

void unixpc_state::ramrombank_map(address_map &map)
{
	map(0x000000, 0x3fffff).rom().region("bootrom", 0);
	map(0x400000, 0x7fffff).rw(FUNC(unixpc_state::ram_mmu_r), FUNC(unixpc_state::ram_mmu_w));
}

/***************************************************************************
    INPUT PORTS
***************************************************************************/

static INPUT_PORTS_START( unixpc )
INPUT_PORTS_END


/***************************************************************************
    MACHINE DRIVERS
***************************************************************************/

static void unixpc_floppies(device_slot_interface &device)
{
	device.option_add("525dd", FLOPPY_525_DD);
}

MACHINE_CONFIG_START(unixpc_state::unixpc)
	// basic machine hardware
	MCFG_DEVICE_ADD("maincpu", M68010, XTAL(10'000'000))
	MCFG_DEVICE_PROGRAM_MAP(unixpc_mem)

	// video hardware
	MCFG_SCREEN_ADD("screen", RASTER)
	MCFG_SCREEN_UPDATE_DRIVER(unixpc_state, screen_update)
	MCFG_SCREEN_RAW_PARAMS(XTAL(20'000'000), 896, 0, 720, 367, 0, 348)
	MCFG_SCREEN_PALETTE("palette")
	// vsync should actually last 17264 pixels

	MCFG_DEFAULT_LAYOUT(layout_unixpc)

	MCFG_PALETTE_ADD_MONOCHROME("palette")

	// internal ram
	MCFG_RAM_ADD(RAM_TAG)
	MCFG_RAM_DEFAULT_SIZE("1M")
	MCFG_RAM_EXTRA_OPTIONS("2M")

	// RAM/ROM bank
	MCFG_DEVICE_ADD("ramrombank", ADDRESS_MAP_BANK, 0)
	MCFG_DEVICE_PROGRAM_MAP(ramrombank_map)
	MCFG_ADDRESS_MAP_BANK_ENDIANNESS(ENDIANNESS_BIG)
	MCFG_ADDRESS_MAP_BANK_DATA_WIDTH(16)
	MCFG_ADDRESS_MAP_BANK_STRIDE(0x400000)

	// floppy
	MCFG_DEVICE_ADD("wd2797", WD2797, 1000000)
	MCFG_WD_FDC_INTRQ_CALLBACK(WRITELINE(*this, unixpc_state, wd2797_intrq_w))
	MCFG_WD_FDC_DRQ_CALLBACK(WRITELINE(*this, unixpc_state, wd2797_drq_w))
	MCFG_FLOPPY_DRIVE_ADD("wd2797:0", unixpc_floppies, "525dd", floppy_image_device::default_floppy_formats)
MACHINE_CONFIG_END


/***************************************************************************
    ROM DEFINITIONS
***************************************************************************/

// ROMs were provided by Michael Lee und imaged by Philip Pemberton
ROM_START( 3b1 )
	ROM_REGION16_BE(0x400000, "bootrom", 0)
	ROM_LOAD16_BYTE("72-00617.15c", 0x000000, 0x002000, CRC(4e93ff40) SHA1(1a97c8d32ec862f7f5fa1032f1688b76ea0672cc))
	ROM_LOAD16_BYTE("72-00616.14c", 0x000001, 0x002000, CRC(c61f7ae0) SHA1(ab3ac29935a2a587a083c4d175a5376badd39058))
ROM_END


/***************************************************************************
    GAME DRIVERS
***************************************************************************/

//    YEAR  NAME  PARENT  COMPAT  MACHINE  INPUT   CLASS         INIT        COMPANY  FULLNAME  FLAGS
COMP( 1985, 3b1,  0,      0,      unixpc,  unixpc, unixpc_state, empty_init, "AT&T",  "3B1",    MACHINE_NOT_WORKING | MACHINE_NO_SOUND )