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
// license:BSD-3-Clause
// copyright-holders:Anthony Kruize,Wilbert Pol
/***************************************************************************

  wswan.c

  Machine file to handle emulation of the Bandai WonderSwan.

  Anthony Kruize
  Wilbert Pol

TODO:
  SRAM sizes should be in kbit instead of kbytes(?). This raises a few
  interesting issues:
  - mirror of smaller <64KBYTE/512kbit sram sizes
  - banking when using 1M or 2M sram sizes

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

#include "includes/wswan.h"
#include "render.h"

#define INTERNAL_EEPROM_SIZE    1024

enum enum_system { TYPE_WSWAN=0, TYPE_WSC };


static const uint8_t ws_portram_init[256] =
{
	0x00, 0x00, 0x00/*?*/, 0xbb, 0x00, 0x00, 0x00, 0x26, 0xfe, 0xde, 0xf9, 0xfb, 0xdb, 0xd7, 0x7f, 0xf5,
	0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x9e, 0x9b, 0x00, 0x00, 0x00, 0x00, 0x99, 0xfd, 0xb7, 0xdf,
	0x30, 0x57, 0x75, 0x76, 0x15, 0x73, 0x70/*77?*/, 0x77, 0x20, 0x75, 0x50, 0x36, 0x70, 0x67, 0x50, 0x77,
	0x57, 0x54, 0x75, 0x77, 0x75, 0x17, 0x37, 0x73, 0x50, 0x57, 0x60, 0x77, 0x70, 0x77, 0x10, 0x73,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x00,
	0x87, 0x00, 0x0c, 0x00, 0x00, 0x00, 0x4f, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0xdb, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x42, 0x00, 0x83, 0x00,
	0x2f, 0x3f, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1,
	0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1,
	0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1,
	0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1, 0xd1
};

/*
    Some fake bios code to initialize some registers and set up some things on the wonderswan.
    The code from f:ffe0 which gets copied to 0:0400 is taken from a wonderswan crystal's initial
    memory settings. Lacking real bios dumps we will use this....

    The setting of SP to 2000h is what's needed to get Wonderswan Colloseum to boot.

    f000:ffc0
    FC             cld
    BC 00 20       mov sp,2000h
    68 00 00       push 0000h
    07             pop es
    68 00 F0       push F000h
    1F             pop ds
    BF 00 04       mov di,0400h
    BE E0 FF       mov si,FFE0h
    B9 10 00       mov cx,0010h
    F3 A4          rep movsb
    B0 2F          mov al,2Fh
    E6 C0          out al,C0h
    EA 00 04 00 00 jmp 0000:0400

    f000:ffe0
    E4 A0          in al, A0h
    0C 01          or al,01h
    E6 A0          out al,A0h
    EA 00 00 FF FF jmp FFFFh:0000h

*/
static const uint8_t ws_fake_bios_code[] = {
	0xfc, 0xbc, 0x00, 0x20, 0x68, 0x00, 0x00, 0x07, 0x68, 0x00, 0xf0, 0x1f, 0xbf, 0x00, 0x04, 0xbe,
	0xe0, 0xff, 0xb9, 0x10, 0x00, 0xf3, 0xa4, 0xb0, 0x2f, 0xe6, 0xc0, 0xea, 0x00, 0x04, 0x00, 0x00,
	0xe4, 0xa0, 0x0c, 0x01, 0xe6, 0xa0, 0xea, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00,
	0xea, 0xc0, 0xff, 0x00, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

void wswan_state::handle_irqs()
{
	if (m_ws_portram[0xb2] & m_ws_portram[0xb6] & WSWAN_IFLAG_HBLTMR)
	{
		m_maincpu->set_input_line_and_vector(0, HOLD_LINE, m_ws_portram[0xb0] + WSWAN_INT_HBLTMR);
	}
	else if (m_ws_portram[0xb2] & m_ws_portram[0xb6] & WSWAN_IFLAG_VBL)
	{
		m_maincpu->set_input_line_and_vector(0, HOLD_LINE, m_ws_portram[0xb0] + WSWAN_INT_VBL);
	}
	else if (m_ws_portram[0xb2] & m_ws_portram[0xb6] & WSWAN_IFLAG_VBLTMR)
	{
		m_maincpu->set_input_line_and_vector(0, HOLD_LINE, m_ws_portram[0xb0] + WSWAN_INT_VBLTMR);
	}
	else if (m_ws_portram[0xb2] & m_ws_portram[0xb6] & WSWAN_IFLAG_LCMP)
	{
		m_maincpu->set_input_line_and_vector(0, HOLD_LINE, m_ws_portram[0xb0] + WSWAN_INT_LCMP);
	}
	else if (m_ws_portram[0xb2] & m_ws_portram[0xb6] & WSWAN_IFLAG_SRX)
	{
		m_maincpu->set_input_line_and_vector(0, HOLD_LINE, m_ws_portram[0xb0] + WSWAN_INT_SRX);
	}
	else if (m_ws_portram[0xb2] & m_ws_portram[0xb6] & WSWAN_IFLAG_RTC)
	{
		m_maincpu->set_input_line_and_vector(0, HOLD_LINE, m_ws_portram[0xb0] + WSWAN_INT_RTC);
	}
	else if (m_ws_portram[0xb2] & m_ws_portram[0xb6] & WSWAN_IFLAG_KEY)
	{
		m_maincpu->set_input_line_and_vector(0, HOLD_LINE, m_ws_portram[0xb0] + WSWAN_INT_KEY);
	}
	else if (m_ws_portram[0xb2] & m_ws_portram[0xb6] & WSWAN_IFLAG_STX)
	{
		m_maincpu->set_input_line_and_vector(0, HOLD_LINE, m_ws_portram[0xb0] + WSWAN_INT_STX);
	}
	else
	{
		m_maincpu->set_input_line(0, CLEAR_LINE);
	}
}

void wswan_state::set_irq_line(int irq)
{
	if (m_ws_portram[0xb2] & irq)
	{
		m_ws_portram[0xb6] |= irq;
		handle_irqs();
	}
}

void wswan_state::dma_sound_cb()
{
	if ((m_sound_dma.enable & 0x88) == 0x80)
	{
		address_space &space = m_maincpu->space(AS_PROGRAM);
		/* TODO: Output sound DMA byte */
		port_w(space, 0x89, space.read_byte(m_sound_dma.source));
		m_sound_dma.size--;
		m_sound_dma.source = (m_sound_dma.source + 1) & 0x0fffff;
		if (m_sound_dma.size == 0)
		{
			m_sound_dma.enable &= 0x7F;
		}
	}
}

void wswan_state::clear_irq_line(int irq)
{
	m_ws_portram[0xb6] &= ~irq;
	handle_irqs();
}

void wswan_state::register_save()
{
	save_item(NAME(m_ws_portram));
	save_item(NAME(m_internal_eeprom));
	save_item(NAME(m_bios_disabled));
	save_item(NAME(m_rotate));

	save_item(NAME(m_sound_dma.source));
	save_item(NAME(m_sound_dma.size));
	save_item(NAME(m_sound_dma.enable));

	if (m_cart->exists())
		m_cart->save_nvram();
}

void wswan_state::common_start()
{
	m_ws_bios_bank = std::make_unique<uint8_t[]>(0x10000);
	memcpy(m_ws_bios_bank.get() + 0xffc0, ws_fake_bios_code, 0x40);

	register_save();

	machine().device<nvram_device>("nvram")->set_base(m_internal_eeprom, INTERNAL_EEPROM_SIZE);

	if (m_cart->exists())
	{
		// ROM
		m_maincpu->space(AS_PROGRAM).install_read_handler(0x20000, 0x2ffff, read8_delegate(FUNC(ws_cart_slot_device::read_rom20),(ws_cart_slot_device*)m_cart));
		m_maincpu->space(AS_PROGRAM).install_read_handler(0x30000, 0x3ffff, read8_delegate(FUNC(ws_cart_slot_device::read_rom30),(ws_cart_slot_device*)m_cart));
		m_maincpu->space(AS_PROGRAM).install_read_handler(0x40000, 0xeffff, read8_delegate(FUNC(ws_cart_slot_device::read_rom40),(ws_cart_slot_device*)m_cart));

		// SRAM
		if (m_cart->get_type() == WS_SRAM)
		{
			m_maincpu->space(AS_PROGRAM).install_read_handler(0x10000, 0x1ffff, read8_delegate(FUNC(ws_cart_slot_device::read_ram),(ws_cart_slot_device*)m_cart));
			m_maincpu->space(AS_PROGRAM).install_write_handler(0x10000, 0x1ffff, write8_delegate(FUNC(ws_cart_slot_device::write_ram),(ws_cart_slot_device*)m_cart));
		}
	}
}

void wswan_state::machine_start()
{
	common_start();
	m_system_type = TYPE_WSWAN;
}

MACHINE_START_MEMBER(wswan_state, wscolor)
{
	common_start();
	m_system_type = TYPE_WSC;
}

void wswan_state::machine_reset()
{
	m_bios_disabled = 0;

	if (m_cart->exists())
		m_rotate = m_cart->get_is_rotated();
	else
		m_rotate = 0;

	/* Intialize ports */
	memcpy(m_ws_portram, ws_portram_init, 256);

	render_target *target = machine().render().first_target();
	target->set_view(m_rotate);

	/* Initialize sound DMA */
	memset(&m_sound_dma, 0, sizeof(m_sound_dma));
}

READ8_MEMBER( wswan_state::bios_r )
{
	if (!m_bios_disabled)
		return m_ws_bios_bank[offset];
	else
		return m_cart->read_rom40(space, offset + 0xb0000);
}

READ8_MEMBER( wswan_state::port_r )
{
	uint8_t value = m_ws_portram[offset];

	if (offset != 2)
		logerror("PC=%X: port read %02X\n", m_maincpu->pc(), offset);

	if (offset < 0x40 || (offset >= 0xa1 && offset < 0xb0))
		return m_vdp->reg_r(space, offset);

	switch (offset)
	{
		case 0x4a:      // Sound DMA source address (low)
			value = m_sound_dma.source & 0xff;
			break;
		case 0x4b:      // Sound DMA source address (high)
			value = (m_sound_dma.source >> 8) & 0xff;
			break;
		case 0x4c:      // Sound DMA source memory segment
			value = (m_sound_dma.source >> 16) & 0xff;
			break;
		case 0x4e:      // Sound DMA transfer size (low)
			value = m_sound_dma.size & 0xff;
			break;
		case 0x4f:      // Sound DMA transfer size (high)
			value = (m_sound_dma.size >> 8) & 0xff;
			break;
		case 0x52:      // Sound DMA start/stop
			value = m_sound_dma.enable;
			break;
		case 0x60:
			value = m_vdp->reg_r(space, offset);
			break;
		case 0xa0:      // Hardware type
			// Bit 0 - Disable/enable Bios
			// Bit 1 - Determine mono/color
			// Bit 2 - Determine color/crystal
			value = value & ~ 0x02;
			if (m_system_type == TYPE_WSC)
				value |= 2;
			break;
		case 0xc0:
		case 0xc1:
		case 0xc2:
		case 0xc3:
		case 0xc4:  // EEPROM data
		case 0xc5:  // EEPROM data
		case 0xc6:
		case 0xc7:
		case 0xc8:
		case 0xc9:
		case 0xca:
		case 0xcb:  // RTC data
		case 0xcc:
		case 0xcd:
		case 0xce:
		case 0xcf:
			value = m_cart->read_io(space, offset & 0x0f);
			break;
	}

	return value;
}

WRITE8_MEMBER( wswan_state::port_w )
{
	address_space &mem = m_maincpu->space(AS_PROGRAM);
	uint8_t input;
	logerror("PC=%X: port write %02X <- %02X\n", m_maincpu->pc(), offset, data);

	if (offset < 0x40 || (offset >= 0xa1 && offset < 0xb0))
	{
		m_vdp->reg_w(space, offset, data);
		return;
	}

	switch (offset)
	{
		case 0x40:  /* DMA source address (low)
		             Bit 0-7 - DMA source address bit 0-7
		             */
		case 0x41:  /* DMA source address (high)
		             Bit 0-7 - DMA source address bit 8-15
		             */
		case 0x42:  /* DMA source bank
		             Bit 0-7 - DMA source bank number
		             */
		case 0x43:  /* DMA destination bank
		             Bit 0-7 - DMA destination bank number
		             */
		case 0x44:  /* DMA destination address (low)
		             Bit 0-7 - DMA destination address bit 0-7
		             */
		case 0x45:  /* DMA destination address (high)
		             Bit 0-7 - DMA destination address bit 8-15
		             */
		case 0x46:  /* Size of copied data (low)
		             Bit 0-7 - DMA size bit 0-7
		             */
		case 0x47:  /* Size of copied data (high)
		             Bit 0-7 - DMA size bit 8-15
		             */
			break;
		case 0x48:  /* DMA control
		             Bit 0-6 - Unknown
		             Bit 7   - DMA stop/start
		             */
			if (data & 0x80)
			{
				uint32_t src, dst;
				uint16_t length;

				src = m_ws_portram[0x40] + (m_ws_portram[0x41] << 8) + (m_ws_portram[0x42] << 16);
				dst = m_ws_portram[0x44] + (m_ws_portram[0x45] << 8) + (m_ws_portram[0x43] << 16);
				length = m_ws_portram[0x46] + (m_ws_portram[0x47] << 8);
				for ( ; length > 0; length--)
				{
					mem.write_byte(dst, mem.read_byte(src));
					src++;
					dst++;
				}
#ifdef MAME_DEBUG
				logerror("DMA  src:%X dst:%X length:%d\n", src, dst, length);
#endif
				m_ws_portram[0x40] = src & 0xff;
				m_ws_portram[0x41] = (src >> 8) & 0xff;
				m_ws_portram[0x44] = dst & 0xff;
				m_ws_portram[0x45] = (dst >> 8) & 0xff;
				m_ws_portram[0x46] = length & 0xff;
				m_ws_portram[0x47] = (length >> 8) & 0xff;
				data &= 0x7f;
			}
			break;
		case 0x4a:  /* Sound DMA source address (low)
		             Bit 0-7 - Sound DMA source address bit 0-7
		             */
			m_sound_dma.source = (m_sound_dma.source & 0x0fff00) | data;
			break;
		case 0x4b:  /* Sound DMA source address (high)
		             Bit 0-7 - Sound DMA source address bit 8-15
		             */
			m_sound_dma.source = (m_sound_dma.source & 0x0f00ff) | (data << 8);
			break;
		case 0x4c:  /* Sound DMA source memory segment
		             Bit 0-3 - Sound DMA source address segment
		             Bit 4-7 - Unknown
		             */
			m_sound_dma.source = (m_sound_dma.source & 0xffff) | ((data & 0x0f) << 16);
			break;
		case 0x4d:  /* Unknown */
			break;
		case 0x4e:  /* Sound DMA transfer size (low)
		             Bit 0-7 - Sound DMA transfer size bit 0-7
		             */
			m_sound_dma.size = (m_sound_dma.size & 0xff00) | data;
			break;
		case 0x4f:  /* Sound DMA transfer size (high)
		             Bit 0-7 - Sound DMA transfer size bit 8-15
		             */
			m_sound_dma.size = (m_sound_dma.size & 0xff) | (data << 8);
			break;
		case 0x50:  /* Unknown */
		case 0x51:  /* Unknown */
			break;
		case 0x52:  /* Sound DMA start/stop
		             Bit 0-6 - Unknown
		             Bit 7   - Sound DMA stop/start
		             */
			m_sound_dma.enable = data;
			break;
		case 0x60:
			m_vdp->reg_w(space, offset, data);
			break;
		case 0x80:  /* Audio 1 freq (lo)
		             Bit 0-7 - Audio channel 1 frequency bit 0-7
		             */
		case 0x81:  /* Audio 1 freq (hi)
		             Bit 0-7 - Audio channel 1 frequency bit 8-15
		             */
		case 0x82:  /* Audio 2 freq (lo)
		             Bit 0-7 - Audio channel 2 frequency bit 0-7
		             */
		case 0x83:  /* Audio 2 freq (hi)
		             Bit 0-7 - Audio channel 2 frequency bit 8-15
		             */
		case 0x84:  /* Audio 3 freq (lo)
		             Bit 0-7 - Audio channel 3 frequency bit 0-7
		             */
		case 0x85:  /* Audio 3 freq (hi)
		             Bit 0-7 - Audio channel 3 frequency bit 8-15
		             */
		case 0x86:  /* Audio 4 freq (lo)
		             Bit 0-7 - Audio channel 4 frequency bit 0-7
		             */
		case 0x87:  /* Audio 4 freq (hi)
		             Bit 0-7 - Audio channel 4 frequency bit 8-15
		             */
		case 0x88:  /* Audio 1 volume
		             Bit 0-3 - Right volume audio channel 1
		             Bit 4-7 - Left volume audio channel 1
		             */
		case 0x89:  /* Audio 2 volume
		             Bit 0-3 - Right volume audio channel 2
		             Bit 4-7 - Left volume audio channel 2
		             */
		case 0x8a:  /* Audio 3 volume
		             Bit 0-3 - Right volume audio channel 3
		             Bit 4-7 - Left volume audio channel 3
		             */
		case 0x8b:  /* Audio 4 volume
		             Bit 0-3 - Right volume audio channel 4
		             Bit 4-7 - Left volume audio channel 4
		             */
		case 0x8c:  /* Sweep step
		             Bit 0-7 - Sweep step
		             */
		case 0x8d:  /* Sweep time
		             Bit 0-7 - Sweep time
		             */
		case 0x8e:  /* Noise control
		             Bit 0-2 - Noise generator type
		             Bit 3   - Reset
		             Bit 4   - Enable
		             Bit 5-7 - Unknown
		             */
		case 0x8f:  /* Sample location
		             Bit 0-7 - Sample address location 0 00xxxxxx xx000000
		             */
		case 0x90:  /* Audio control
		             Bit 0   - Audio 1 enable
		             Bit 1   - Audio 2 enable
		             Bit 2   - Audio 3 enable
		             Bit 3   - Audio 4 enable
		             Bit 4   - Unknown
		             Bit 5   - Audio 2 voice mode enable
		             Bit 6   - Audio 3 sweep mode enable
		             Bit 7   - Audio 4 noise mode enable
		             */
		case 0x91:  /* Audio output
		             Bit 0   - Mono select
		             Bit 1-2 - Output volume
		             Bit 3   - External stereo
		             Bit 4-6 - Unknown
		             Bit 7   - External speaker (Read-only, set by hardware)
		             */
		case 0x92:  /* Noise counter shift register (lo)
		             Bit 0-7 - Noise counter shift register bit 0-7
		             */
		case 0x93:  /* Noise counter shift register (hi)
		             Bit 0-6 - Noise counter shift register bit 8-14
		             bit 7   - Unknown
		             */
		case 0x94:  /* Master volume
		             Bit 0-3 - Master volume
		             Bit 4-7 - Unknown
		             */
			m_sound->port_w(space, offset, data);
			break;
		case 0xa0:  /* Hardware type - this is probably read only
		             Bit 0   - Enable cartridge slot and/or disable bios
		             Bit 1   - Hardware type: 0 = WS, 1 = WSC
		             Bit 2-7 - Unknown
		             */
			if ((data & 0x01) && !m_bios_disabled)
				m_bios_disabled = 1;
			break;

		case 0xb0:  /* Interrupt base vector
		             Bit 0-7 - Interrupt base vector
		             */
			break;
		case 0xb1:  /* Communication byte
		             Bit 0-7 - Communication byte
		             */
			break;
		case 0xb2:  /* Interrupt enable
		             Bit 0   - Serial transmit interrupt enable
		             Bit 1   - Key press interrupt enable
		             Bit 2   - RTC alarm interrupt enable
		             Bit 3   - Serial receive interrupt enable
		             Bit 4   - Drawing line detection interrupt enable
		             Bit 5   - VBlank timer interrupt enable
		             Bit 6   - VBlank interrupt enable
		             Bit 7   - HBlank timer interrupt enable
		             */
			break;
		case 0xb3:  /* serial communication control
		             Bit 0   - Receive complete
		             Bit 1   - Error
		             Bit 2   - Send complete
		             Bit 3-4 - Unknown
		             Bit 5   - Send data interrupt generation
		             Bit 6   - Connection speed: 0 = 9600 bps, 1 = 38400 bps
		             bit 7   - Receive data interrupt generation
		             */
			//          data |= 0x02;
			m_ws_portram[0xb1] = 0xff;
			if (data & 0x80)
			{
				//              m_ws_portram[0xb1] = 0x00;
				data |= 0x04;
			}
			if (data & 0x20)
			{
				//              data |= 0x01;
			}
			break;
		case 0xb5:  /* Read controls
		             Bit 0-3 - Current state of input lines (read-only)
		             Bit 4-6 - Select line of inputs to read
		             001 - Read Y cursors
		             010 - Read X cursors
		             100 - Read START,A,B buttons
		             Bit 7   - Unknown
		             */
			data = data & 0xf0;
			switch (data)
		{
			case 0x10:  /* Read Y cursors: Y1 - Y2 - Y3 - Y4 */
				input = m_cursy->read();
				if (m_rotate) // reorient controls if the console is rotated
				{
					if (input & 0x01) data |= 0x02;
					if (input & 0x02) data |= 0x04;
					if (input & 0x04) data |= 0x08;
					if (input & 0x08) data |= 0x01;
				}
				else
					data = data | input;
				break;
			case 0x20:  /* Read X cursors: X1 - X2 - X3 - X4 */
				input = m_cursx->read();
				if (m_rotate) // reorient controls if the console is rotated
				{
					if (input & 0x01) data |= 0x02;
					if (input & 0x02) data |= 0x04;
					if (input & 0x04) data |= 0x08;
					if (input & 0x08) data |= 0x01;
				}
				else
					data = data | input;
				break;
			case 0x40:  /* Read buttons: START - A - B */
				data = data | m_buttons->read();
				break;
		}
			break;
		case 0xb6:  /* Interrupt acknowledge
		             Bit 0   - Serial transmit interrupt acknowledge
		             Bit 1   - Key press interrupt acknowledge
		             Bit 2   - RTC alarm interrupt acknowledge
		             Bit 3   - Serial receive interrupt acknowledge
		             Bit 4   - Drawing line detection interrupt acknowledge
		             Bit 5   - VBlank timer interrupt acknowledge
		             Bit 6   - VBlank interrupt acknowledge
		             Bit 7   - HBlank timer interrupt acknowledge
		             */
			clear_irq_line(data);
			data = m_ws_portram[0xb6];
			break;
		case 0xba:  /* Internal EEPROM data (low)
		             Bit 0-7 - Internal EEPROM data transfer bit 0-7
		             */
		case 0xbb:  /* Internal EEPROM data (high)
		             Bit 0-7 - Internal EEPROM data transfer bit 8-15
		             */
			break;
		case 0xbc:  /* Internal EEPROM address (low)
		             Bit 0-7 - Internal EEPROM address bit 1-8
		             */
		case 0xbd:  /* Internal EEPROM address (high)
		             Bit 0   - Internal EEPROM address bit 9(?)
		             Bit 1-7 - Unknown
		             Only 1KByte internal EEPROM??
		             */
			break;
		case 0xbe:  /* Internal EEPROM command
		             Bit 0   - Read complete (read only)
		             Bit 1   - Write complete (read only)
		             Bit 2-3 - Unknown
		             Bit 4   - Read
		             Bit 5   - Write
		             Bit 6   - Protect
		             Bit 7   - Initialize
		             */
			if (data & 0x20)
			{
				uint16_t addr = ( ( ( m_ws_portram[0xbd] << 8 ) | m_ws_portram[0xbc] ) << 1 ) & 0x1FF;
				m_internal_eeprom[ addr ] = m_ws_portram[0xba];
				m_internal_eeprom[ addr + 1 ] = m_ws_portram[0xbb];
				data |= 0x02;
			}
			else if ( data & 0x10 )
			{
				uint16_t addr = ( ( ( m_ws_portram[0xbd] << 8 ) | m_ws_portram[0xbc] ) << 1 ) & 0x1FF;
				m_ws_portram[0xba] = m_internal_eeprom[ addr ];
				m_ws_portram[0xbb] = m_internal_eeprom[ addr + 1];
				data |= 0x01;
			}
			else
			{
				logerror( "Unsupported internal EEPROM command: %X\n", data );
			}
			break;
		case 0xc0:  // ROM bank $40000-$fffff
		case 0xc1:  // SRAM bank
		case 0xc2:  // ROM bank $20000-$2ffff
		case 0xc3:  // ROM bank $30000-$3ffff
		case 0xc4:
		case 0xc5:
		case 0xc6:  // EEPROM address / command
		case 0xc7:  // EEPROM address / command
		case 0xc8:  // EEPROM command
		case 0xc9:
		case 0xca:  // RTC command
		case 0xcb:  // RTC data
		case 0xcc:
		case 0xcd:
		case 0xce:
		case 0xcf:
			m_cart->write_io(space, offset & 0x0f, data);
			break;
		default:
			logerror( "Write to unsupported port: %X - %X\n", offset, data );
			break;
	}

	/* Update the port value */
	m_ws_portram[offset] = data;
}