summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/bus/msx/cart/ram.cpp
blob: 022e8e6b394da63c3dba612a049436545b8d5828 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
// license:BSD-3-Clause
// copyright-holders:Wilbert Pol
/*
Emulation of memory expansions for the MSX system.

Standard 16K RAM expansions:
- Addcom ADMSM 301
- Casio OR-216
- General RJ-102
- Hitachi MP-RA01H
- Mitsubishi ML-16RAM
- National CF-2131
- Philips VU 0031
- Sanyo MRP-16
- Sony HBM-16
- Toshiba HX-M250

Standard 32K RAM expansions:
- Addcom ADMSM 302
- Pioneer PX-RA32
- Yamaha URM-01

Standard 48K RAM expansions:
- Addcom ADMSM 303
- Neos RM-48

Standard 64K RAM expansions:
- Casio OR-264
- Philips VU 0034
- Sanyo Memoire Ram 64Ko
- Sanyo MRP-64
- Sharp-Epcom HB-4100
- Sony HBM-64
- Spectravideo SVI-747
- Toshiba HX-M251
- Walther Miller WM 0587

Not supported:
- Fujitsu MB22451 - Fujitsu FM-X only, adds 16K memory and a printer port
- Yamaha SRE-01 - 60pin 32K memory expansion
- Yamaha SRM-01 - 60pin 32K memory expansion and slot expander



256KB Memmory Mapper expansions
- R. & J.Jansen Memory Mapper 256

512KB Memory Mapper expansions
- Green MSX WBM512
- Hardware Partners TM 512KB
- HSH RE-512 MM
- Padial LPE-512KBSRAM-V3
- R. & J.Jansen Memory Mapper 512
- Sony HBM-512

768KB Memory Mapper expansions
- ASCII MEM-768

1MB Memory Mapper expansions
- 8bits4ever MEGA-MAPPER 1024KB
- Digital KC MSX Memory Mapper 1024KB
- Hardware Partners TM 1M
- MK MSX Memory Mapper 1024KB
- MSX Club Gouda Memory Mapper 1MB
- Popolon MSX Memory Mapper

2MB Memory Mapper expansions
- 8bits4ever MEGA-MAPPER 2048KB
- Digital KC MSX Memory Mapper 2048KB
- MFP Extended Memory-2048K
- MK MSX Memory Mapper 2048KB
- MSX Club Gouda Memory Mapper 2MB

4MB Memory Mapper expansions
- 8bits4ever MEGA-MAPPER 4096KB
- Digital KC MSX Memory Mapper 4096KB
- MK MSX Memory Mapper 4096KB
- MSX Club Gouda Memory Mapper 4MB
- Padial LPE-4MB-V42KP
- T.N.S. Addram
- Tecnobytes Double RAM

Known issues/problems:
- Switching Tecnobytes Double RAM from Memory Mapper to  MegaRAM mode will cause
  the emulation to look up when the system is using the Double RAM as main
  memory. It is unknown if this also happens on a real system.

TODO:
- Unknown which parts of memory are used for the MegaRAM 8KB pages.


Not supported memory mappers:
- 8bits4ever SD-512
- RBSC Carnivore2
- Classic PC 16MB Expansion Memory - 4 x 4MB memory mapper
- GR8NET
- MSX Cartridge Shop MegaFlashROM SCC+ SD
- Padial LPE-4FMB-V8SKP - 4MB memory mapper + MegaRam mode
- Playsonic - 4MB memory mapper, up to 16MB through extra register
- Stichting CODE MCR-025 - 256KB memory mapper + RAM Disk + Printer buffer
- Stichting CODE MCR-051 - 512KB memory mapper + RAM Disk + Printer buffer
- Stichting CODE MCR-076 - 768KB memory mapper + RAM Disk + Printer buffer
- Stichting CODE MCR-102 - 1MB memory mapper + RAM Disk + Printer buffer
- Stichting CODE MCR-204 - 2MB memory mapper + RAM Disk + Printer buffer
*/
#include "emu.h"
#include "ram.h"
#include "slotoptions.h"

#include "bus/msx/slot/cartridge.h"
#include "bus/generic/slot.h"
#include "sound/sn76496.h"



DECLARE_DEVICE_TYPE(MSX_CART_16K_RAM,      msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_32K_RAM,      msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_48K_RAM,      msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_64K_RAM,      msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_256K_MM_RAM,  msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_512K_MM_RAM,  msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_768K_MM_RAM,  msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_1024K_MM_RAM, msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_2048K_MM_RAM, msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_4096K_MM_RAM, msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_DOUBLE_RAM,   msx_cart_interface)
DECLARE_DEVICE_TYPE(MSX_CART_MMM,          msx_cart_interface)

void msx_cart_ram_register_options(device_slot_interface &device)
{
	using namespace bus::msx::cart;
	device.option_add(slotoptions::RAM16K,     MSX_CART_16K_RAM);
	device.option_add(slotoptions::RAM32K,     MSX_CART_32K_RAM);
	device.option_add(slotoptions::RAM48K,     MSX_CART_48K_RAM);
	device.option_add(slotoptions::RAM64K,     MSX_CART_64K_RAM);
	device.option_add(slotoptions::MM256K,     MSX_CART_256K_MM_RAM);
	device.option_add(slotoptions::MM512K,     MSX_CART_512K_MM_RAM);
	device.option_add(slotoptions::MM768K,     MSX_CART_768K_MM_RAM);
	device.option_add(slotoptions::MM1024K,    MSX_CART_1024K_MM_RAM);
	device.option_add(slotoptions::MM2048K,    MSX_CART_2048K_MM_RAM);
	device.option_add(slotoptions::MM4096K,    MSX_CART_4096K_MM_RAM);
	device.option_add(slotoptions::DOUBLE_RAM, MSX_CART_DOUBLE_RAM);
	device.option_add(slotoptions::MMM,        MSX_CART_MMM);
}

namespace {

class msx_cart_base_ram_device : public device_t, public msx_cart_interface
{
protected:
	msx_cart_base_ram_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock, u32 ram_size)
		: device_t(mconfig, type, tag, owner, clock)
		, msx_cart_interface(mconfig, *this)
		, m_ram_size(ram_size)
	{ }

	virtual void device_start() override
	{
		m_ram = std::make_unique<u8[]>(m_ram_size);
		save_pointer(NAME(m_ram), m_ram_size);
	}

	u8 *ram_data()
	{
		return m_ram.get();
	}

	u32 get_ram_size() const
	{
		return m_ram_size;
	}

private:
	std::unique_ptr<u8[]> m_ram;
	const u32 m_ram_size;
};


class msx_cart_16k_ram_device : public msx_cart_base_ram_device
{
public:
	msx_cart_16k_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_ram_device(mconfig, MSX_CART_16K_RAM, tag, owner, clock, 16 * 1024)
	{ }

protected:
	virtual void device_start() override
	{
		msx_cart_base_ram_device::device_start();
		page(2)->install_ram(0x8000, 0xbfff, ram_data());
	}
};

class msx_cart_32k_ram_device : public msx_cart_base_ram_device
{
public:
	msx_cart_32k_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_ram_device(mconfig, MSX_CART_32K_RAM, tag, owner, clock, 32 * 1024)
	{ }

protected:
	virtual void device_start() override
	{
		msx_cart_base_ram_device::device_start();
		page(0)->install_ram(0x0000, 0x3fff, ram_data());
		page(1)->install_ram(0x4000, 0x7fff, ram_data() + 0x4000);
	}
};

class msx_cart_48k_ram_device : public msx_cart_base_ram_device
{
public:
	msx_cart_48k_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_ram_device(mconfig, MSX_CART_48K_RAM, tag, owner, clock, 48 * 1024)
	{ }

protected:
	virtual void device_start() override
	{
		msx_cart_base_ram_device::device_start();
		page(0)->install_ram(0x0000, 0x3fff, ram_data());
		page(1)->install_ram(0x4000, 0x7fff, ram_data() + 0x4000);
		page(2)->install_ram(0x8000, 0xbfff, ram_data() + 0x8000);
	}
};

class msx_cart_64k_ram_device : public msx_cart_base_ram_device
{
public:
	msx_cart_64k_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_ram_device(mconfig, MSX_CART_64K_RAM, tag, owner, clock, 64 * 1024)
	{ }

protected:
	virtual void device_start() override
	{
		msx_cart_base_ram_device::device_start();
		page(0)->install_ram(0x0000, 0x3fff, ram_data());
		page(1)->install_ram(0x4000, 0x7fff, ram_data() + 0x4000);
		page(2)->install_ram(0x8000, 0xbfff, ram_data() + 0x8000);
		page(3)->install_ram(0xc000, 0xffff, ram_data() + 0xc000);
	}
};


class msx_cart_base_mm_ram_device : public msx_cart_base_ram_device
{
protected:
	msx_cart_base_mm_ram_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock, u32 ram_size)
		: msx_cart_base_ram_device(mconfig, type, tag, owner, clock, ram_size)
		, m_rambank(*this, "rambank%u", 0U)
		, m_bank_mask(0)
	{ }

	virtual void device_start() override ATTR_COLD;

	template <int Bank> void bank_w(u8 data);

	memory_bank_array_creator<4> m_rambank;
	u8 m_bank_mask;
};

void msx_cart_base_mm_ram_device::device_start()
{
	msx_cart_base_ram_device::device_start();

	m_bank_mask = device_generic_cart_interface::map_non_power_of_two(
			unsigned(get_ram_size() / 0x4000),
			[this] (unsigned entry, unsigned page)
			{
				for (int i = 0; i < 4; i++)
					m_rambank[i]->configure_entry(entry, ram_data() + 0x4000 * page);
			}
	);

	// The MSX system allows multiple devices to react to I/O, so we use taps.
	io_space().install_write_tap(0xfc, 0xfc, "bank0", [this] (offs_t, u8& data, u8){ this->bank_w<0>(data); });
	io_space().install_write_tap(0xfd, 0xfd, "bank1", [this] (offs_t, u8& data, u8){ this->bank_w<1>(data); });
	io_space().install_write_tap(0xfe, 0xfe, "bank2", [this] (offs_t, u8& data, u8){ this->bank_w<2>(data); });
	io_space().install_write_tap(0xff, 0xff, "bank3", [this] (offs_t, u8& data, u8){ this->bank_w<3>(data); });

	page(0)->install_readwrite_bank(0x0000, 0x3fff, m_rambank[0]);
	page(1)->install_readwrite_bank(0x4000, 0x7fff, m_rambank[1]);
	page(2)->install_readwrite_bank(0x8000, 0xbfff, m_rambank[2]);
	page(3)->install_readwrite_bank(0xc000, 0xffff, m_rambank[3]);

	m_rambank[0]->set_entry(3);
	m_rambank[1]->set_entry(2);
	m_rambank[2]->set_entry(1);
	m_rambank[3]->set_entry(0);
}

template <int Bank>
void msx_cart_base_mm_ram_device::bank_w(u8 data)
{
	m_rambank[Bank]->set_entry(data & m_bank_mask);
}


class msx_cart_256k_mm_ram_device : public msx_cart_base_mm_ram_device
{
public:
	msx_cart_256k_mm_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_mm_ram_device(mconfig, MSX_CART_256K_MM_RAM, tag, owner, clock, 256 * 1024)
	{ }
};

class msx_cart_512k_mm_ram_device : public msx_cart_base_mm_ram_device
{
public:
	msx_cart_512k_mm_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_mm_ram_device(mconfig, MSX_CART_512K_MM_RAM, tag, owner, clock, 512 * 1024)
	{ }
};

class msx_cart_768k_mm_ram_device : public msx_cart_base_mm_ram_device
{
public:
	msx_cart_768k_mm_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_mm_ram_device(mconfig, MSX_CART_768K_MM_RAM, tag, owner, clock, 768 * 1024)
	{ }
};

class msx_cart_1024k_mm_ram_device : public msx_cart_base_mm_ram_device
{
public:
	msx_cart_1024k_mm_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_mm_ram_device(mconfig, MSX_CART_1024K_MM_RAM, tag, owner, clock, 1024 * 1024)
	{ }
};

class msx_cart_2048k_mm_ram_device : public msx_cart_base_mm_ram_device
{
public:
	msx_cart_2048k_mm_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_mm_ram_device(mconfig, MSX_CART_2048K_MM_RAM, tag, owner, clock, 2048 * 1024)
	{ }
};

class msx_cart_4096k_mm_ram_device : public msx_cart_base_mm_ram_device
{
public:
	msx_cart_4096k_mm_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_mm_ram_device(mconfig, MSX_CART_4096K_MM_RAM, tag, owner, clock, 4096 * 1024)
	{ }
};


class msx_cart_mmm_device : public msx_cart_base_mm_ram_device
{
public:
	msx_cart_mmm_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_mm_ram_device(mconfig, MSX_CART_MMM, tag, owner, clock, 1024 * 1024)
		, m_sn76489a(*this, "sn76489a")
		, m_access_enabled(false)
		, m_sn76489_enabled(false)
	{ }

protected:
	virtual void device_start() override ATTR_COLD;
	virtual void device_add_mconfig(machine_config &config) override ATTR_COLD;

private:
	required_device<sn76496_base_device> m_sn76489a;
	bool m_access_enabled;
	bool m_sn76489_enabled;
};

void msx_cart_mmm_device::device_start()
{
	msx_cart_base_mm_ram_device::device_start();

	m_access_enabled = false;
	m_sn76489_enabled = false;

	io_space().install_write_tap(0x3c, 0x3c, "ena_access", [this] (offs_t, u8& data, u8){ this->m_access_enabled = BIT(data, 7); });
	io_space().install_write_tap(0x3f, 0x3f, "sn76489w", [this] (offs_t, u8& data, u8){ if (m_sn76489_enabled) this->m_sn76489a->write(data); });

	page(2)->install_write_tap(0x803c, 0x803c, "ena_sn76489", [this] (offs_t, u8& data, u8){ if (m_access_enabled) this->m_sn76489_enabled |= BIT(data, 6); });
	page(2)->install_read_tap(0x80fc, 0x80fc, "map00r", [this] (offs_t, u8& data, u8){ if (m_access_enabled) data = 0xc0 | this->m_rambank[0]->entry(); });
	page(2)->install_read_tap(0x80fd, 0x80fd, "map40r", [this] (offs_t, u8& data, u8){ if (m_access_enabled) data = 0xc0 | this->m_rambank[1]->entry(); });
	page(2)->install_read_tap(0x80fe, 0x80fe, "map80r", [this] (offs_t, u8& data, u8){ if (m_access_enabled) data = 0xc0 | this->m_rambank[2]->entry(); });
	page(2)->install_read_tap(0x80ff, 0x80ff, "mapc0r", [this] (offs_t, u8& data, u8){ if (m_access_enabled) data = 0xc0 | this->m_rambank[3]->entry(); });
	page(2)->install_write_tap(0x80fc, 0x80fc, "map00w", [this] (offs_t, u8& data, u8){ if (m_access_enabled) this->bank_w<0>(data); });
	page(2)->install_write_tap(0x80fd, 0x80fd, "map40w", [this] (offs_t, u8& data, u8){ if (m_access_enabled) this->bank_w<1>(data); });
	page(2)->install_write_tap(0x80fe, 0x80fe, "map80w", [this] (offs_t, u8& data, u8){ if (m_access_enabled) this->bank_w<2>(data); });
	page(2)->install_write_tap(0x80ff, 0x80ff, "mapc0w", [this] (offs_t, u8& data, u8){ if (m_access_enabled) this->bank_w<3>(data); });

	save_item(NAME(m_access_enabled));
	save_item(NAME(m_sn76489_enabled));
}

void msx_cart_mmm_device::device_add_mconfig(machine_config &config)
{
	SN76489A(config, m_sn76489a, DERIVED_CLOCK(1, 3));
	if (parent_slot())
		m_sn76489a->add_route(ALL_OUTPUTS, soundin(), 0.8);
}



class msx_cart_double_ram_device : public msx_cart_base_mm_ram_device
{
public:
	msx_cart_double_ram_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: msx_cart_base_mm_ram_device(mconfig, MSX_CART_DOUBLE_RAM, tag, owner, clock, 4 * 1024 * 1024)
		, m_mode_switch(*this, "MODE")
		, m_view{ {*this, "view0"}, {*this, "view1"}, {*this, "view2"}, {*this, "view3"} }
		, m_mrview{ {*this, "mrview0"}, {*this, "mrview1"}, {*this, "mrview2"}, {*this, "mrview3"} }
		, m_megaram(false)
	{ }

	DECLARE_INPUT_CHANGED_MEMBER(mode_callback);

protected:
	virtual void device_start() override ATTR_COLD;
	virtual void device_reset() override ATTR_COLD;
	virtual ioport_constructor device_input_ports() const override ATTR_COLD;

private:
	static constexpr u8 MODE_RO = 0;
	static constexpr u8 MODE_RW = 1;
	static constexpr u8 MODE_MM = 0;
	static constexpr u8 MODE_MR = 1;

	required_ioport m_mode_switch;
	memory_view m_view[4];
	memory_view m_mrview[4];
	bool m_megaram;

	void set_page_views();
};

static INPUT_PORTS_START(double_ram_mode_switch)
	PORT_START("MODE")
	PORT_CONFNAME(0x01, 0x01, "Mode") PORT_CHANGED_MEMBER(DEVICE_SELF, msx_cart_double_ram_device, mode_callback, 0)
	PORT_CONFSETTING(0x00, "Memory Mapper")
	PORT_CONFSETTING(0x01, "MegaRAM")
INPUT_PORTS_END

ioport_constructor msx_cart_double_ram_device::device_input_ports() const
{
	return INPUT_PORTS_NAME(double_ram_mode_switch);
}

void msx_cart_double_ram_device::device_start()
{
	msx_cart_base_ram_device::device_start();

	m_bank_mask = device_generic_cart_interface::map_non_power_of_two(
			unsigned(get_ram_size() / 0x4000),
			[this] (unsigned entry, unsigned page)
			{
				for (int i = 0; i < 4; i++)
					m_rambank[i]->configure_entry(entry, ram_data() + 0x4000 * page);
			}
	);

	page(0)->install_view(0x0000, 0x3fff, m_view[0]);
	page(1)->install_view(0x4000, 0x7fff, m_view[1]);
	page(2)->install_view(0x8000, 0xbfff, m_view[2]);
	page(3)->install_view(0xc000, 0xffff, m_view[3]);

	m_view[0][MODE_MM].install_readwrite_bank(0x0000, 0x3fff, m_rambank[0]);
	m_view[0][MODE_MR];

	m_view[1][MODE_MM].install_readwrite_bank(0x4000, 0x7fff, m_rambank[1]);
	m_view[1][MODE_MR].install_view(0x4000, 0x5fff, m_mrview[0]);
	m_view[1][MODE_MR].install_view(0x6000, 0x7fff, m_mrview[1]);

	m_view[2][MODE_MM].install_readwrite_bank(0x8000, 0xbfff, m_rambank[2]);
	m_view[2][MODE_MR].install_view(0x8000, 0x9fff, m_mrview[2]);
	m_view[2][MODE_MR].install_view(0xa000, 0xbfff, m_mrview[3]);

	m_view[3][MODE_MM].install_readwrite_bank(0xc000, 0xffff, m_rambank[3]);
	m_view[3][MODE_MR];

	m_mrview[0][MODE_RO].install_read_bank(0x4000, 0x5fff, m_rambank[0]);
	m_mrview[0][MODE_RO].install_write_handler(0x4000, 0x4000, write8smo_delegate(*this, [this] (u8 data) { this->m_rambank[0]->set_entry(data); }, "bank_4000"));
	m_mrview[0][MODE_RW].install_readwrite_bank(0x4000, 0x5fff, m_rambank[0]);

	m_mrview[1][MODE_RO].install_read_bank(0x6000, 0x7fff, m_rambank[1]);
	m_mrview[1][MODE_RO].install_write_handler(0x6000, 0x6000, write8smo_delegate(*this, [this] (u8 data) { this->m_rambank[1]->set_entry(data); }, "bank_6000"));
	m_mrview[1][MODE_RW].install_readwrite_bank(0x6000, 0x7fff, m_rambank[1]);

	m_mrview[2][MODE_RO].install_read_bank(0x8000, 0x9fff, m_rambank[2]);
	m_mrview[2][MODE_RO].install_write_handler(0x8000, 0x8000, write8smo_delegate(*this, [this] (u8 data) { this->m_rambank[2]->set_entry(data); }, "bank_8000"));
	m_mrview[2][MODE_RW].install_readwrite_bank(0x8000, 0x9fff, m_rambank[2]);

	m_mrview[3][MODE_RO].install_read_bank(0xa000, 0xbfff, m_rambank[3]);
	m_mrview[3][MODE_RO].install_write_handler(0xa000, 0xa000, write8smo_delegate(*this, [this] (u8 data) { this->m_rambank[3]->set_entry(data); }, "bank_a000"));
	m_mrview[3][MODE_RW].install_readwrite_bank(0xa000, 0xbfff, m_rambank[3]);

	io_space().install_read_tap(0x8e, 0x8e, "megaram_w", [this] (offs_t, u8&, u8) { if (m_megaram) for (int i = 0; i < 4; i++) m_mrview[i].select(MODE_RW); } );
	io_space().install_write_tap(0x8e, 0x8e, "megaram_r", [this] (offs_t, u8&, u8) { if (m_megaram) for (int i = 0; i < 4; i++) m_mrview[i].select(MODE_RO); } );

	// The MSX system allows multiple devices to react to I/O, so we use taps.
	io_space().install_write_tap(0xfc, 0xfc, "bank0", [this] (offs_t, u8& data, u8){ if (!m_megaram) this->bank_w<0>(data); });
	io_space().install_write_tap(0xfd, 0xfd, "bank1", [this] (offs_t, u8& data, u8){ if (!m_megaram) this->bank_w<1>(data); });
	io_space().install_write_tap(0xfe, 0xfe, "bank2", [this] (offs_t, u8& data, u8){ if (!m_megaram) this->bank_w<2>(data); });
	io_space().install_write_tap(0xff, 0xff, "bank3", [this] (offs_t, u8& data, u8){ if (!m_megaram) this->bank_w<3>(data); });

	save_item(NAME(m_megaram));

	for (int i = 0; i < 4; i++)
	{
		m_mrview[i].select(MODE_RO);
		m_rambank[i]->set_entry(i);
	}
}

void msx_cart_double_ram_device::device_reset()
{
	m_megaram = BIT(m_mode_switch->read(), 0);
	set_page_views();
}

INPUT_CHANGED_MEMBER(msx_cart_double_ram_device::mode_callback)
{
	m_megaram = BIT(newval, 0);
	set_page_views();
}

void msx_cart_double_ram_device::set_page_views()
{
	for (int i = 0; i < 4; i++)
		m_view[i].select(m_megaram ? MODE_MR : MODE_MM);
}

} // anonymous namespace


DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_16K_RAM,      msx_cart_interface, msx_cart_16k_ram_device,      "msx_cart_16k_ram",      "Generic MSX 16K RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_32K_RAM,      msx_cart_interface, msx_cart_32k_ram_device,      "msx_cart_32k_ram",      "Generic MSX 32K RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_48K_RAM,      msx_cart_interface, msx_cart_48k_ram_device,      "msx_cart_48k_ram",      "Generic MSX 48K RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_64K_RAM,      msx_cart_interface, msx_cart_64k_ram_device,      "msx_cart_64k_ram",      "Generic MSX 64K RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_256K_MM_RAM,  msx_cart_interface, msx_cart_256k_mm_ram_device,  "msx_cart_256k_mm_ram",  "Generic MSX 256K MM RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_512K_MM_RAM,  msx_cart_interface, msx_cart_512k_mm_ram_device,  "msx_cart_512k_mm_ram",  "Generic MSX 512K MM RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_768K_MM_RAM,  msx_cart_interface, msx_cart_768k_mm_ram_device,  "msx_cart_768k_mm_ram",  "Generic MSX 768K MM RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_1024K_MM_RAM, msx_cart_interface, msx_cart_1024k_mm_ram_device, "msx_cart_1024k_mm_ram", "Generic MSX 1024K MM RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_2048K_MM_RAM, msx_cart_interface, msx_cart_2048k_mm_ram_device, "msx_cart_2048k_mm_ram", "Generic MSX 2048K MM RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_4096K_MM_RAM, msx_cart_interface, msx_cart_4096k_mm_ram_device, "msx_cart_4096k_mm_ram", "Generic MSX 4096K MM RAM Expansion")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_DOUBLE_RAM,   msx_cart_interface, msx_cart_double_ram_device,   "msx_cart_double_ram",   "Tecnobytes Double RAM")
DEFINE_DEVICE_TYPE_PRIVATE(MSX_CART_MMM,          msx_cart_interface, msx_cart_mmm_device,          "msx_cart_mmm",          "Popolon Musical Memory Mapper")