86Box/src/machine/m_at_t3100e.c

/*
 * VARCem	Virtual ARchaeological Computer EMulator.
 *		An emulator of (mostly) x86-based PC systems and devices,
 *		using the ISA,EISA,VLB,MCA  and PCI system buses, roughly
 *		spanning the era between 1981 and 1995.
 *
 *		This file is part of the VARCem Project.
 *
 *		Implementation of the Toshiba T3100e.
 *
 *		The Toshiba 3100e is a 286-based portable.
 *
 *		To bring up the BIOS setup screen hold down the 'Fn' key
 *		on booting.
 *
 *		Memory management
 *		~~~~~~~~~~~~~~~~~
 * 
 *		Motherboard memory is divided into:
 *		- Conventional memory: Either 512k or 640k
 *		- Upper memory:        Either 512k or 384k, depending on
 *				       amount of conventional memory.
 *				       Upper memory can be used as EMS or XMS.
 *		- High memory:         0-4Mb, depending on RAM installed.
 *				       The BIOS setup screen allows some or
 *				       all of this to be used as EMS; the
 *				       remainder is XMS.
 * 
 *		Additional memory (either EMS or XMS) can also be provided
 *		by ISA expansion cards.
 *
 *		Under test in PCem, the BIOS will boot with up to 65368Kb
 *		of memory in total (16Mb less 16k). However it will give
 *		an error with RAM sizes above 8Mb, if any of the high
 *		memory is allocated as EMS, because the builtin EMS page
 *		registers can only access up to 8Mb.
 *
 *		Memory is controlled by writes to I/O port 8084h:
 *		  Bit 7: Always 0  }
 *		  Bit 6: Always 1  } These bits select which motherboard
 *		  Bit 5: Always 0  } function to access.
 *		  Bit 4: Set to treat upper RAM as XMS
 *		  Bit 3: Enable external RAM boards? 
 *		  Bit 2: Set for 640k conventional memory, clear for 512k
 *		  Bit 1: Enable RAM beyond 1Mb.
 *		  Bit 0: Enable EMS.
 *
 *		The last value written to this port is saved at 0040:0093h,
 *		and in CMOS memory at offset 0x37. If the top bit of the
 *		CMOS byte is set, then high memory is being provided by
 *		an add-on card rather than the mainboard; accordingly,
 *		the BIOS will not allow high memory to be used as EMS.
 *
 *		EMS is controlled by 16 page registers:
 *
 *		Page mapped at		0xD000	0xD400	0xD800	0xDC00
 *		------------------------------------------------------
 *		Pages 0x00-0x7F		 0x208	0x4208	0x8208	0xc208
 *		Pages 0x80-0xFF		 0x218	0x4218	0x8218	0xc218
 *		Pages 0x100-0x17F	 0x258	0x4258	0x8258	0xc258
 *		Pages 0x180-0x1FF	 0x268	0x4268	0x8268	0xc268
 *
 *		The value written has bit 7 set to enable EMS, reset to
 *		disable it.
 *
 *		So:
 *		OUT 0x208,  0x80  will page in the first 16k page at 0xD0000.
 *		OUT 0x208,  0x00  will page out EMS, leaving nothing at 0xD0000.
 *		OUT 0x4208, 0x80  will page in the first 16k page at 0xD4000.
 *		OUT 0x218,  0x80  will page in the 129th 16k page at 0xD0000.
 *		etc.
 * 
 *		To use EMS from DOS, you will need the Toshiba EMS driver
 *		(TOSHEMM.ZIP). This supports the above system, plus further
 *		ranges of ports at 0x_2A8, 0x_2B8, 0x_2C8.
 *
 *		Features not implemented:
 *		> Four video fonts.
 *		> BIOS-controlled mapping of serial ports to IRQs.
 *		> Custom keyboard controller. This has a number of extra
 *		  commands in the 0xB0-0xBC range, for such things as turbo
 *		  on/off, and switching the keyboard between AT and PS/2
 *		  modes. Currently I have only implemented command 0xBB,
 *		  so that self-test completes successfully. Commands include:
 *
 *		  0xB0:   Turbo on
 *		  0xB1:   Turbo off
 *		  0xB2:   Internal display on?
 *		  0xB3:   Internal display off?
 *		  0xB5:   Get settings byte (bottom bit is color/mono setting)
 *		  0xB6:   Set settings byte
 *		  0xB7:   Behave as 101-key PS/2 keyboard
 *		  0xB8:   Behave as 84-key AT keyboard
 *		  0xBB:   Return a byte, bit 2 is Fn key state, other bits unknown.
 *
 *		The other main I/O port needed to POST is:
 *		  0x8084: System control.
 *		  Top 3 bits give command, bottom 5 bits give parameters.
 *		  000 => set serial port IRQ / addresses
 *		  bit 4:    IRQ5 serial port base: 1 => 0x338, 0 => 0x3E8
 *		  bits 3, 2, 0 specify serial IRQs for COM1, COM2, COM3:
 *			    00 0 => 4, 3, 5
 *                          00 1 => 4, 5, 3
 *                          01 0 => 3, 4, 5
 *                          01 1 => 3, 5, 4
 *                          10 0 => 4, -, 3
 *                          10 1 => 3, -, 4 
 *		  010 => set memory mappings
 *			 bit 4 set if upper RAM is XMS
 *			 bit 3 enable add-on memory boards beyond 5Mb?
 *                       bit 2 set for 640k sysram, clear for 512k sysram
 *                       bit 1 enable mainboard XMS
 *                       bit 0 enable mainboard EMS
 *		  100 => set parallel mode / LCD settings
 *                       bit 4 set for bidirectional parallel port
 *                       bit 3 set to disable internal CGA
 *                       bit 2 set for single-pixel LCD font
 *                       bits 0,1 for display font
 *
 * Version:	@(#)m_at_t3100e.c	1.0.6	2018/10/22
 *
 * Authors:	Fred N. van Kempen, <decwiz@yahoo.com>
 *		Miran Grca, <mgrca8@gmail.com>
 *		Sarah Walker, <tommowalker@tommowalker.co.uk>
 *
 *		Copyright 2017,2018 Fred N. van Kempen.
 *		Copyright 2016-2018 Miran Grca.
 *		Copyright 2008-2018 Sarah Walker.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free  Software  Foundation; either  version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is  distributed in the hope that it will be useful, but
 * WITHOUT   ANY  WARRANTY;  without  even   the  implied  warranty  of
 * MERCHANTABILITY  or FITNESS  FOR A PARTICULAR  PURPOSE. See  the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the:
 *
 *   Free Software Foundation, Inc.
 *   59 Temple Place - Suite 330
 *   Boston, MA 02111-1307
 *   USA.
 */
#include <stdarg.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#define HAVE_STDARG_H
#include "../86box.h"
#include "../timer.h"
#include "../io.h"
#include "../mouse.h"
#include "../mem.h"
#include "../device.h"
#include "../keyboard.h"
#include "../rom.h"
#include "../cpu/cpu.h"
#include "../floppy/fdd.h"
#include "../floppy/fdc.h"
#include "machine.h"
#include "m_at_t3100e.h"


extern uint8_t *ram;		/* Physical RAM */

void at_init();


/* The T3100e motherboard can (and does) dynamically reassign RAM between
 * conventional, XMS and EMS. This translates to monkeying with the mappings.
 */

extern mem_mapping_t base_mapping;

extern mem_mapping_t ram_low_mapping;	/* This is to switch conventional RAM
					 * between 512k and 640k */

extern mem_mapping_t ram_mid_mapping;	/* This will not be used */

extern mem_mapping_t ram_high_mapping;	/* This is RAM beyond 1Mb if any */

extern uint8_t *ram;

static unsigned t3100e_ems_page_reg[] =
{
	0x208, 0x4208, 0x8208, 0xc208,	/* The first four map the first 2Mb */
					/* of RAM into the page frame */
	0x218, 0x4218, 0x8218, 0xc218,	/* The next four map the next 2Mb */
					/* of RAM */
	0x258, 0x4258, 0x8258, 0xc258,	/* and so on. */
	0x268, 0x4268, 0x8268, 0xc268,
};

struct t3100e_ems_regs
{
	uint8_t page[16];
	mem_mapping_t mapping[4];
	uint32_t page_exec[4];	/* Physical location of memory pages */
	uint32_t upper_base;	/* Start of upper RAM */
	uint8_t	 upper_pages;	/* Pages of EMS available from upper RAM */
	uint8_t  upper_is_ems;	/* Upper RAM is EMS? */
	mem_mapping_t upper_mapping;
	uint8_t	notify;		/* Notification from keyboard controller */
	uint8_t turbo;		/* 0 for 6MHz, else full speed */
	uint8_t mono;		/* Emulates PC/AT 'mono' motherboard switch */
				/* Bit 0 is 0 for colour, 1 for mono */
} t3100e_ems;

void t3100e_ems_out(uint16_t addr, uint8_t val, void *p);


#ifdef ENABLE_T3100E_LOG
int t3100e_do_log = ENABLE_T3100E_LOG;


static void
t3100e_log(const char *fmt, ...)
{
   va_list ap;

   if (t3100e_do_log)
   {
	va_start(ap, fmt);
	pclog_ex(fmt, ap);
	va_end(ap);
   }
}
#else
#define t3100e_log(fmt, ...)
#endif


/* Given a memory address (which ought to be in the page frame at 0xD0000), 
 * which page does it relate to? */
static int addr_to_page(uint32_t addr)
{
	if ((addr & 0xF0000) == 0xD0000)
	{
		return ((addr >> 14) & 3);
	}
	return -1;
}

/* And vice versa: Given a page slot, which memory address does it 
 * correspond to? */
static uint32_t page_to_addr(int pg)
{
	return 0xD0000 + ((pg & 3) * 16384);
}

/* Given an EMS page ID, return its physical address in RAM. */
uint32_t t3100e_ems_execaddr(struct t3100e_ems_regs *regs, 
					int pg, uint16_t val)
{
	uint32_t addr;

	if (!(val & 0x80)) return 0;	/* Bit 7 reset => not mapped */

	val &= 0x7F;
	val += (0x80 * (pg >> 2));      /* The high bits of the register bank */
					/* are used to extend val to allow up */
					/* to 8Mb of EMS to be accessed */

	/* Is it in the upper memory range? */
	if (regs->upper_is_ems)
	{
		if (val < regs->upper_pages)
		{
			addr = regs->upper_base + 0x4000 * val;
			return addr;
		}
		val -= regs->upper_pages;
	}
	/* Otherwise work down from the top of high RAM (so, the more EMS,
	 * the less XMS) */
	if ((val * 0x4000) + 0x100000 >= (mem_size * 1024))
	{
		return 0;	/* Not enough high RAM for this page */
	}
	/* High RAM found */
	addr = (mem_size * 1024) - 0x4000 * (val + 1);

	return addr;
}


/* The registers governing the EMS ports are in rather a nonintuitive order */
static int port_to_page(uint16_t addr)
{
	switch (addr)
	{
		case 0x208:  return  0; 
		case 0x4208: return  1; 
		case 0x8208: return  2; 
		case 0xC208: return  3; 
		case 0x218:  return  4; 
		case 0x4218: return  5; 
		case 0x8218: return  6; 
		case 0xC218: return  7; 
		case 0x258:  return  8;
		case 0x4258: return  9;
		case 0x8258: return 10;
		case 0xC258: return 11;
		case 0x268:  return 12;
		case 0x4268: return 13;
		case 0x8268: return 14;
		case 0xC268: return 15;
	}
	return -1;
}

/* Used to dump the memory mapping table, for debugging
void dump_mappings()
{
	mem_mapping_t *mm = base_mapping.next;

	if (!t3100e_log) return;
	while (mm)
	{
		const char *name = "";
		uint32_t offset = (uint32_t)(mm->exec - ram);

		if (mm == &ram_low_mapping ) name = "LOW ";
		if (mm == &ram_mid_mapping ) name = "MID ";
		if (mm == &ram_high_mapping) name = "HIGH";
		if (mm == &t3100e_ems.upper_mapping) name = "UPPR";
		if (mm == &t3100e_ems.mapping[0]) 
		{
			name = "EMS0";
			offset = t3100e_ems.page_exec[0];
		}
		if (mm == &t3100e_ems.mapping[1]) 
		{
			name = "EMS1";
			offset = t3100e_ems.page_exec[1];
		}
		if (mm == &t3100e_ems.mapping[2])
		{
			name = "EMS2";
			offset = t3100e_ems.page_exec[2];
		}
		if (mm == &t3100e_ems.mapping[3]) 
		{
			name = "EMS3";
			offset = t3100e_ems.page_exec[3];
		}

		t3100e_log("  %p | base=%05x size=%05x %c @ %06x %s\n", mm, 
			mm->base, mm->size, mm->enable ? 'Y' : 'N', 
			offset, name);

		mm = mm->next;
	}
}*/

void t3100e_map_ram(uint8_t val)
{
	int n;
	int32_t upper_len;

	t3100e_log("OUT 0x8084, %02x [ set memory mapping :", val | 0x40); 
	if (val & 1) t3100e_log("ENABLE_EMS ");
	if (val & 2) t3100e_log("ENABLE_XMS ");
	if (val & 4) t3100e_log("640K ");
	if (val & 8) t3100e_log("X8X ");
	if (val & 16) t3100e_log("UPPER_IS_XMS ");
	t3100e_log("\n");

	/* Bit 2 controls size of conventional memory */
	if (val & 4) 
	{
		t3100e_ems.upper_base  = 0xA0000;
		t3100e_ems.upper_pages = 24;
	}
	else	
	{
		t3100e_ems.upper_base = 0x80000;
		t3100e_ems.upper_pages = 32;
	}
	upper_len = t3100e_ems.upper_pages * 16384;

	mem_mapping_set_addr(&ram_low_mapping, 0, t3100e_ems.upper_base);
	/* Bit 0 set if upper RAM is EMS */
	t3100e_ems.upper_is_ems = (val & 1);

	/* Bit 1 set if high RAM is enabled */
	if (val & 2)
	{
		mem_mapping_enable(&ram_high_mapping);
	}
	else
	{
		mem_mapping_disable(&ram_high_mapping);
	}

	/* Bit 4 set if upper RAM is mapped to high memory 
         * (and bit 1 set if XMS enabled) */
	if ((val & 0x12) == 0x12)
	{
		mem_mapping_set_addr(&t3100e_ems.upper_mapping,
					mem_size * 1024,
					upper_len);
		mem_mapping_enable(&t3100e_ems.upper_mapping);
		mem_mapping_set_exec(&t3100e_ems.upper_mapping, ram + t3100e_ems.upper_base);
	}
	else
	{
		mem_mapping_disable(&t3100e_ems.upper_mapping);
	}
	/* Recalculate EMS mappings */
	for (n = 0; n < 4; n++)
	{
		t3100e_ems_out(t3100e_ems_page_reg[n], t3100e_ems.page[n], 
				&t3100e_ems);
	}

	//dump_mappings();
}


void t3100e_notify_set(uint8_t value)
{
	t3100e_ems.notify = value;
}

void t3100e_mono_set(uint8_t value)
{
       t3100e_ems.mono = value;
}

uint8_t t3100e_mono_get(void)
{
       return t3100e_ems.mono;
}

void t3100e_turbo_set(uint8_t value)
{
	t3100e_ems.turbo = value;
	if (!value)
	{
		cpu_dynamic_switch(0);	/* 286/6 */
	}
	else
	{
		cpu_dynamic_switch(cpu);
	}
}



uint8_t t3100e_sys_in(uint16_t addr, void *p)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)p;

	/* The low 4 bits always seem to be 0x0C. The high 4 are a 
	 * notification sent by the keyboard controller when it detects
	 * an [Fn] key combination */
	t3100e_log("IN 0x8084\n");
	return 0x0C | (regs->notify << 4);
}



/* Handle writes to the T3100e system control port at 0x8084 */
void t3100e_sys_out(uint16_t addr, uint8_t val, void *p)
{
//	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)p;

	switch (val & 0xE0)
	{
		case 0x00: /* Set serial port IRQs. Not implemented */
			t3100e_log("OUT 0x8084, %02x [ set serial port IRQs]\n", val); 
			break;
		case 0x40: /* Set RAM mappings. */
			t3100e_map_ram(val & 0x1F);		
			break;

		case 0x80: /* Set video options. */
			t3100e_video_options_set(val & 0x1F); break;

			/* Other options not implemented. */
		default: t3100e_log("OUT 0x8084, %02x\n", val); break;
	}
}


uint8_t t3100e_config_get(void)
{
/* The byte returned:
	Bit 7: Set if internal plasma display enabled
	Bit 6: Set if running at 6MHz, clear at full speed
	Bit 5: Always 1?
	Bit 4: Set if the FD2MB jumper is present (internal floppy is ?tri-mode)
	Bit 3: Clear if the FD2 jumper is present (two internal floppies)
	Bit 2: Set if the internal drive is A:, clear if B:
	Bit 1: Set if the parallel port is configured as a floppy connector
               for the second drive.
	Bit 0: Set if the F2HD jumper is present (internal floppy is 720k)
 */
	uint8_t value = 0x28;	/* Start with bits 5 and 3 set. */

	int type_a = fdd_get_type(0);
	int type_b = fdd_get_type(1);
	int prt_switch;		/* External drive type: 0=> none, 1=>A, 2=>B */

/* Get display setting */
	if (t3100e_display_get()) value |= 0x80;
	if (!t3100e_ems.turbo)	  value |= 0x40;

/* Try to determine the floppy types.*/

	prt_switch = (type_b ? 2 : 0);
	switch(type_a)
	{
/* Since a T3100e cannot have an internal 5.25" drive, mark 5.25" A: drive as 
 * being external, and set the internal type based on type_b. */
		case 1:			/* 360k */
		case 2:			/* 1.2Mb */
		case 3:			/* 1.2Mb RPMx2*/
			prt_switch = 1;	/* External drive is A: */
			switch (type_b)
			{
				case 1:				/* 360k */
				case 4: value |= 1;    break;	/* 720k */
				case 6: value |= 0x10; break;	/* Tri-mode */
				/* All others will be treated as 1.4M */
			}
			break;
		case 4: value |= 0x01;	/* 720k */
			if (type_a == type_b) 
			{
				value &= (~8);	/* Two internal drives */
				prt_switch = 0;	/* No external drive */
			}
			break;
		case 5:	/* 1.4M */
		case 7:	/* 2.8M */
			if (type_a == type_b) 
			{
				value &= (~8);	/* Two internal drives */
				prt_switch = 0;	/* No external drive */
			}
			break;
		case 6:	/* 3-mode */
			value |= 0x10;
			if (type_a == type_b) 
			{
				value &= (~8);	/* Two internal drives */
				prt_switch = 0;	/* No external drive */
			}
			break;
	}	/* End switch */
	switch (prt_switch)
	{
		case 0:	value |= 4; break;	/* No external floppy */
		case 1:	value |= 2; break;	/* External floppy is A: */
		case 2:	value |= 6; break;	/* External floppy is B: */
	}
	return value;
}


/* Read EMS page register */
uint8_t t3100e_ems_in(uint16_t addr, void *p)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)p;
	
	int page = port_to_page(addr);
	if (page >= 0)
		return regs->page[page];
	else {
		fatal("t3100e_ems_in(): invalid address");
		return 0xff;
	}
}

/* Write EMS page register */
void t3100e_ems_out(uint16_t addr, uint8_t val, void *p)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)p;
	int pg = port_to_page(addr);

	if (pg == -1)
		return;

	regs->page_exec[pg & 3] = t3100e_ems_execaddr(regs, pg, val);
	t3100e_log("EMS: page %d %02x -> %02x [%06x]\n",
			pg, regs->page[pg], val, regs->page_exec[pg & 3]);
	regs->page[pg] = val;

	pg &= 3;
/* Bit 7 set if page is enabled, reset if page is disabled */
	if (regs->page_exec[pg])
	{
		t3100e_log("Enabling EMS RAM at %05x\n",
				page_to_addr(pg));
		mem_mapping_enable(&regs->mapping[pg]);
		mem_mapping_set_exec(&regs->mapping[pg], ram + regs->page_exec[pg]);
	}
	else
	{
		t3100e_log("Disabling EMS RAM at %05x\n",
				page_to_addr(pg));
		mem_mapping_disable(&regs->mapping[pg]);
	}
}


/* Read RAM in the EMS page frame */
static uint8_t ems_read_ram(uint32_t addr, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;
	int pg = addr_to_page(addr);

	if (pg < 0) return 0xFF;
	addr = regs->page_exec[pg] + (addr & 0x3FFF);
	return ram[addr];	
}




static uint16_t ems_read_ramw(uint32_t addr, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;
	int pg = addr_to_page(addr);

	if (pg < 0) return 0xFF;
	//t3100e_log("ems_read_ramw addr=%05x ", addr);
	addr = regs->page_exec[pg] + (addr & 0x3FFF);
	//t3100e_log("-> %06x val=%04x\n", addr, *(uint16_t *)&ram[addr]);	
	return *(uint16_t *)&ram[addr];	
}


static uint32_t ems_read_raml(uint32_t addr, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;
	int pg = addr_to_page(addr);

	if (pg < 0) return 0xFF;
	addr = regs->page_exec[pg] + (addr & 0x3FFF);
	return *(uint32_t *)&ram[addr];	
}

/* Write RAM in the EMS page frame */
static void ems_write_ram(uint32_t addr, uint8_t val, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;
	int pg = addr_to_page(addr);

	if (pg < 0) return;
	addr = regs->page_exec[pg] + (addr & 0x3FFF);
	ram[addr] = val;	
}


static void ems_write_ramw(uint32_t addr, uint16_t val, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;
	int pg = addr_to_page(addr);

	if (pg < 0) return;
	//t3100e_log("ems_write_ramw addr=%05x ", addr);
	addr = regs->page_exec[pg] + (addr & 0x3FFF);
	//t3100e_log("-> %06x val=%04x\n", addr, val);

	*(uint16_t *)&ram[addr] = val;	
}


static void ems_write_raml(uint32_t addr, uint32_t val, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;
	int pg = addr_to_page(addr);

	if (pg < 0) return;
	addr = regs->page_exec[pg] + (addr & 0x3FFF);
	*(uint32_t *)&ram[addr] = val;	
}



/* Read RAM in the upper area. This is basically what the 'remapped' 
 * mapping in mem.c does, except that the upper area can move around */
static uint8_t upper_read_ram(uint32_t addr, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;

	addr = (addr - (1024 * mem_size)) + regs->upper_base;
	return ram[addr];	
}

static uint16_t upper_read_ramw(uint32_t addr, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;

	addr = (addr - (1024 * mem_size)) + regs->upper_base;
	return *(uint16_t *)&ram[addr];	
}

static uint32_t upper_read_raml(uint32_t addr, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;

	addr = (addr - (1024 * mem_size)) + regs->upper_base;
	return *(uint32_t *)&ram[addr];	
}


static void upper_write_ram(uint32_t addr, uint8_t val, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;

	addr = (addr - (1024 * mem_size)) + regs->upper_base;
	ram[addr] = val;	
}


static void upper_write_ramw(uint32_t addr, uint16_t val, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;

	addr = (addr - (1024 * mem_size)) + regs->upper_base;
	*(uint16_t *)&ram[addr] = val;	
}



static void upper_write_raml(uint32_t addr, uint32_t val, void *priv)
{
	struct t3100e_ems_regs *regs = (struct t3100e_ems_regs *)priv;

	addr = (addr - (1024 * mem_size)) + regs->upper_base;
	*(uint32_t *)&ram[addr] = val;	
}




int machine_at_t3100e_init(const machine_t *model)
{
	int ret;

	ret = bios_load_linear(L"roms/machines/t3100e/t3100e.rom",
			       0x000f0000, 65536, 0);

	if (bios_only || !ret)
		return ret;

	int pg;

        memset(&t3100e_ems, 0, sizeof(t3100e_ems));
        
        machine_at_common_ide_init(model);

	device_add(&keyboard_at_toshiba_device);
	device_add(&fdc_at_device);

	/* Hook up system control port */
	io_sethandler(0x8084, 0x0001, 
			t3100e_sys_in, NULL, NULL,
			t3100e_sys_out, NULL, NULL, &t3100e_ems);

	/* Start monitoring all 16 EMS registers */
	for (pg = 0; pg < 16; pg++) 
	{
		io_sethandler(t3100e_ems_page_reg[pg], 0x0001, 
				t3100e_ems_in, NULL, NULL,
				t3100e_ems_out, NULL, NULL, &t3100e_ems); 
	}

	/* Map the EMS page frame */
	for (pg = 0; pg < 4; pg++)
	{
		t3100e_log("Adding memory map at %x for page %d\n", page_to_addr(pg), pg);
		mem_mapping_add(&t3100e_ems.mapping[pg], 
			page_to_addr(pg), 16384, 
			ems_read_ram,  ems_read_ramw,  ems_read_raml,
			ems_write_ram, ems_write_ramw, ems_write_raml,
			NULL, MEM_MAPPING_EXTERNAL, 
			&t3100e_ems);
		/* Start them all off disabled */
		mem_mapping_disable(&t3100e_ems.mapping[pg]);
	}
	/* Mapping for upper RAM when in use as XMS*/
	mem_mapping_add(&t3100e_ems.upper_mapping, mem_size * 1024, 384 * 1024,
			upper_read_ram, upper_read_ramw, upper_read_raml,
			upper_write_ram, upper_write_ramw, upper_write_raml,
			NULL, MEM_MAPPING_INTERNAL, &t3100e_ems);
	mem_mapping_disable(&t3100e_ems.upper_mapping);

	device_add(&t3100e_device);

	return ret;
}