summaryrefslogtreecommitdiffstatshomepage
path: root/src/mame/audio/segag80r.cpp
blob: 12cc48e6b402d8983acf8350ed32b69f85ff1ae3 (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
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************

    Sega G-80 raster hardware

    Across these games, there's a mixture of discrete sound circuitry,
    speech boards, ADPCM samples, and a TMS3617 music chip.

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

#include "emu.h"
#include "includes/segag80r.h"

#include "audio/segag80r.h"
#include "sound/dac.h"
#include "sound/volt_reg.h"

#include "speaker.h"

/*************************************
 *
 *  Constants
 *
 *************************************/

#define SEGA005_555_TIMER_FREQ      (1.44 / ((15000 + 2 * 4700) * 1.5e-6))
#define SEGA005_COUNTER_FREQ        (100000)    /* unknown, just a guess */

DEFINE_DEVICE_TYPE(SEGA005, sega005_sound_device, "sega005_sound", "Sega 005 Custom Sound")

sega005_sound_device::sega005_sound_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
	: device_t(mconfig, SEGA005, tag, owner, clock)
	, device_sound_interface(mconfig, *this)
	, m_sega005_sound_timer(nullptr)
	, m_sega005_stream(nullptr)
{
}

//-------------------------------------------------
//  device_start - device-specific startup
//-------------------------------------------------

void sega005_sound_device::device_start()
{
	segag80r_state *state = machine().driver_data<segag80r_state>();

	/* create the stream */
	m_sega005_stream = machine().sound().stream_alloc(*this, 0, 1, SEGA005_COUNTER_FREQ);

	/* create a timer for the 555 */
	m_sega005_sound_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(sega005_sound_device::sega005_auto_timer), this));

	/* set the initial sound data */
	state->m_sound_data = 0x00;
	state->sega005_update_sound_data();
}

//-------------------------------------------------
//  sound_stream_update - handle a stream update
//-------------------------------------------------

void sega005_sound_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples)
{
	segag80r_state *state = machine().driver_data<segag80r_state>();
	const uint8_t *sound_prom = state->memregion("proms")->base();
	int i;

	/* no implementation yet */
	for (i = 0; i < samples; i++)
	{
		if (!(state->m_sound_state[1] & 0x10) && (++state->m_square_count & 0xff) == 0)
		{
			state->m_square_count = sound_prom[state->m_sound_data & 0x1f];

			/* hack - the RC should filter this out */
			if (state->m_square_count != 0xff)
				state->m_square_state += 2;
		}

		outputs[0][i] = (state->m_square_state & 2) ? 0x7fff : 0x0000;
	}
}





/*************************************
 *
 *  Astro Blaster sound hardware
 *
 *************************************/

/*
    Description of Astro Blaster sounds (in the hope of future discrete goodness):

    CD4017 = decade counter with one output per decoded stage (10 outputs altogether)
    CD4024 = 7-bit counter with 7 outputs


    "V" signal
    ----------
        CD4017 @ U15:
            reset by RATE RESET signal = 1
            clocked by falling edge of ATTACK signal
            +12V output from here goes through a diode and one of 10 resistors:
                0 = 120k
                1 = 82k
                2 = 62k
                3 = 56k
                4 = 47k
                5 = 39k
                6 = 35k
                7 = 27k
                8 = 24k
                9 = 22k
            and then in series through a 22k resistor

        Op-amp @ U6 takes the WARP signal and the output of CD4017 @ U15
            and forms the signal "V" which is used to control the invader
            sounds


        How to calculate the output voltage at U16 labeled (V).
        (Derrick Renaud)

        First you have an inverting amp.  To get the gain you
        use G=-Rf/Ri, where Rf=R178=22k.  Ri is the selected
        resistor on the output of U15.

        The input voltage to the amp (pin 6) will always be
        about 12V - 0.5V (diode drop in low current circuit) =
        11.5V.

        Now you need to calculate the reference voltage on the
        + input (pin 5).  Depending on the state of WARP...

        If the warp data is 0, then U31 inverts it to an Open
        Collector high, meaning WARP is out of circuit. So:
        Vref = 12V * (R163)/(R162+R163)
             = 12V * 10k/(10K+4.7k)
             = 8.163V

        When warp data is 1, then U31 inverts it to low,
        grounding R164 putting it in parallel with R163,
        giving:
        Vref = 12V * (R163||R164)/(R163||R164 +R162)
             = 12V * 5k/(5k+4.7k)
             = 6.186V

        Now to get the control voltage V:
        V = (Vi - Vref) * G + Vref
          = (11.5V - Vref) * G + Vref

        That gives you the control voltage at V.  From there I
        would have to millman the voltage with the internal
        voltage/resistors of the 555 to get the actual used
        control voltage.

        But it seems you just want a range, so just use the
        above info to get the highest and lowest voltages
        generated, and create the frequency shift you desire.
        Remember as the control voltage (V) lowers, the
        frequency increases.



    INVADER-1 output
    ----------------




    INVADER-2 output
    ----------------
        555 timer @ U13 in astable mode with the following parameters:
            R1 = 10k
            R2 = 100k
            C = 0.0022u
            CV = "V" signal
            Reset = (PORT076 & 0x02)
        Output goes to CD4024 @ U12

        CD4024 @ U12:
            reset through some unknown means
            clocked by 555 timer @ U13
            +12 output from here goes through a resistor ladder:
                Q1 -> 82k
                Q2 -> 39k
                Q3 -> 22k
                Q4 -> 10k
        Summed output from here is INVADER-2


    INVADER-3 output
    ----------------
        555 timer at U17 in astable mode with the following parameters:
            R1 = 10k
            R2 = 68k
            C = 0.1u
            CV = some combination of "V" and "W" signals
            Reset = (PORT076 & 0x04)
        Output from here is INVADER-3

*/

static const char *const astrob_sample_names[] =
{
	"*astrob",
	"invadr1",      /* 0 */
	"winvadr1",     /* 1 */
	"invadr2",      /* 2 */
	"winvadr2",     /* 3 */
	"invadr3",      /* 4 */
	"winvadr3",     /* 5 */
	"invadr4",      /* 6 */
	"winvadr4",     /* 7 */
	"asteroid",     /* 8 */
	"refuel",       /* 9 */
	"pbullet",      /* 10 */
	"ebullet",      /* 11 */
	"eexplode",     /* 12 */
	"pexplode",     /* 13 */
	"deedle",       /* 14 */
	"sonar",        /* 15 */
	nullptr
};


MACHINE_CONFIG_START(segag80r_state::astrob_sound_board)

	/* sound hardware */
	MCFG_DEVICE_ADD("samples", SAMPLES)
	MCFG_SAMPLES_CHANNELS(11)
	MCFG_SAMPLES_NAMES(astrob_sample_names)
	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "speaker", 0.25)
MACHINE_CONFIG_END


/*************************************
 *
 *  Astro Blaster sound triggers
 *
 *************************************/

WRITE8_MEMBER(segag80r_state::astrob_sound_w)
{
	static const float attack_resistor[10] =
	{
		120.0f, 82.0f, 62.0f, 56.0f, 47.0f, 39.0f, 33.0f, 27.0f, 24.0f, 22.0f
	};
	float freq_factor;

	uint8_t diff = data ^ m_sound_state[offset];
	m_sound_state[offset] = data;

	switch (offset)
	{
		case 0:
			/* INVADER-1: channel 0 */
			if ((diff & 0x01) && !(data & 0x01)) m_samples->start(0, (data & 0x80) ? 0 : 1, true);
			if ((data & 0x01) && m_samples->playing(0)) m_samples->stop(0);

			/* INVADER-2: channel 1 */
			if ((diff & 0x02) && !(data & 0x02)) m_samples->start(1, (data & 0x80) ? 2 : 3, true);
			if ((data & 0x02) && m_samples->playing(1)) m_samples->stop(1);

			/* INVADER-3: channel 2 */
			if ((diff & 0x04) && !(data & 0x04)) m_samples->start(2, (data & 0x80) ? 4 : 5, true);
			if ((data & 0x04) && m_samples->playing(2)) m_samples->stop(2);

			/* INVADER-4: channel 3 */
			if ((diff & 0x08) && !(data & 0x08)) m_samples->start(3, (data & 0x80) ? 6 : 7, true);
			if ((data & 0x08) && m_samples->playing(3)) m_samples->stop(3);

			/* ASTROIDS: channel 4 */
			if ((diff & 0x10) && !(data & 0x10)) m_samples->start(4, 8, true);
			if ((data & 0x10) && m_samples->playing(4)) m_samples->stop(4);

			/* MUTE */
			machine().sound().system_mute(data & 0x20);

			/* REFILL: channel 5 */
			if (!(data & 0x40) && !m_samples->playing(5)) m_samples->start(5, 9);
			if ( (data & 0x40) && m_samples->playing(5))  m_samples->stop(5);

			/* WARP: changes which sample is played for the INVADER samples above */
			if (diff & 0x80)
			{
				if (m_samples->playing(0)) m_samples->start(0, (data & 0x80) ? 0 : 1, true);
				if (m_samples->playing(1)) m_samples->start(1, (data & 0x80) ? 2 : 3, true);
				if (m_samples->playing(2)) m_samples->start(2, (data & 0x80) ? 4 : 5, true);
				if (m_samples->playing(3)) m_samples->start(3, (data & 0x80) ? 6 : 7, true);
			}
			break;

		case 1:
			/* LASER #1: channel 6 */
			if ((diff & 0x01) && !(data & 0x01)) m_samples->start(6, 10);

			/* LASER #2: channel 7 */
			if ((diff & 0x02) && !(data & 0x02)) m_samples->start(7, 11);

			/* SHORT EXPL: channel 8 */
			if ((diff & 0x04) && !(data & 0x04)) m_samples->start(8, 12);

			/* LONG EXPL: channel 8 */
			if ((diff & 0x08) && !(data & 0x08)) m_samples->start(8, 13);

			/* ATTACK RATE */
			if ((diff & 0x10) && !(data & 0x10)) m_sound_rate = (m_sound_rate + 1) % 10;

			/* RATE RESET */
			if (!(data & 0x20)) m_sound_rate = 0;

			/* BONUS: channel 9 */
			if ((diff & 0x40) && !(data & 0x40)) m_samples->start(9, 14);

			/* SONAR: channel 10 */
			if ((diff & 0x80) && !(data & 0x80)) m_samples->start(10, 15);
			break;
	}

	/* the samples were recorded with sound_rate = 0, so we need to scale */
	/* the frequency as a fraction of that; these equations come from */
	/* Derrick's analysis above; we compute the inverted scale factor to */
	/* account for the fact that frequency goes up as CV goes down */
	/* WARP is already taken into account by the differing samples above */
	freq_factor  = (11.5f - 8.163f) * (-22.0f / attack_resistor[0]) + 8.163f;
	freq_factor /= (11.5f - 8.163f) * (-22.0f / attack_resistor[m_sound_rate]) + 8.163f;

	/* adjust the sample rate of invader sounds based the sound_rate */
	/* this is an approximation */
	if (m_samples->playing(0)) m_samples->set_frequency(0, m_samples->base_frequency(0) * freq_factor);
	if (m_samples->playing(1)) m_samples->set_frequency(1, m_samples->base_frequency(1) * freq_factor);
	if (m_samples->playing(2)) m_samples->set_frequency(2, m_samples->base_frequency(2) * freq_factor);
	if (m_samples->playing(3)) m_samples->set_frequency(3, m_samples->base_frequency(3) * freq_factor);
}



/*************************************
 *
 *  005 sound hardware
 *
 *************************************/

/*
    005

    The Sound Board consists of the following:

    An 8255:
        Port A controls the sounds that use discrete circuitry
            A0 - Large Expl. Sound Trig
            A1 - Small Expl. Sound Trig
            A2 - Drop Sound Bomb Trig
            A3 - Shoot Sound Pistol Trig
            A4 - Missile Sound Trig
            A5 - Helicopter Sound Trig
            A6 - Whistle Sound Trig
            A7 - <unused>

      Port B controls the melody generator (described below)

      Port C is apparently unused


    Melody Generator:

        555 timer frequency = 1.44/((R1 + 2R2)*C)
        R1 = 15e3
        R2 = 4.7e3
        C=1.5e-6
        Frequency = 39.344 Hz

        Auto timer is enabled if port B & 0x20 == 1
        Auto timer is reset if 2716 value & 0x20 == 0

        Manual timer is enabled if port B & 0x20 == 0
        Manual timer is clocked if port B & 0x40 goes from 0 to 1

        Both auto and manual timers clock LS393 counter
        Counter is held to 0 if port B & 0x10 == 1

        Output of LS393 >> 1 selects low 7 bits of lookup in 2716.
        High 4 bits come from port B bits 0-3.

        Low 5 bits of output from 2716 look up value in 6331 PROM at U8 (32x8)

        8-bit output of 6331 at U8 is loaded into pair of LS161 counters whenever they overflow.
        LS161 counters are clocked somehow (not clear how)

        Carry output from LS161 counters (overflowing 8 bits) goes to the B
            input on the LS293 counter at U14.
        Rising edge of B input clocks bit 1 of counter (effectively adding 2).
        Output B (bit 1) is mixed with output D (bit 3) with different weights
            through a small RC circuit and fed into the 4391 input at U32.

        The 4391 output is the final output.
*/

static const char *const sega005_sample_names[] =
{
	"*005",
	"lexplode",     /* 0 */
	"sexplode",     /* 1 */
	"dropbomb",     /* 2 */
	"shoot",        /* 3 */
	"missile",      /* 4 */
	"helicopt",     /* 5 */
	"whistle",      /* 6 */
	nullptr
};


MACHINE_CONFIG_START(segag80r_state::sega005_sound_board)

	MCFG_DEVICE_ADD("ppi8255", I8255A, 0)
	MCFG_I8255_OUT_PORTA_CB(WRITE8(*this, segag80r_state, sega005_sound_a_w))
	MCFG_I8255_OUT_PORTB_CB(WRITE8(*this, segag80r_state, sega005_sound_b_w))

	/* sound hardware */

	MCFG_DEVICE_ADD("samples", SAMPLES)
	MCFG_SAMPLES_CHANNELS(7)
	MCFG_SAMPLES_NAMES(sega005_sample_names)
	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "speaker", 0.25)

	MCFG_DEVICE_ADD("005", SEGA005, 0)
	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "speaker", 0.25)
MACHINE_CONFIG_END


/*************************************
 *
 *  005 sound triggers
 *
 *************************************/

WRITE8_MEMBER(segag80r_state::sega005_sound_a_w)
{
	uint8_t diff = data ^ m_sound_state[0];
	m_sound_state[0] = data;

	/* LARGE EXPL: channel 0 */
	if ((diff & 0x01) && !(data & 0x01)) m_samples->start(0, 0);

	/* SMALL EXPL: channel 1 */
	if ((diff & 0x02) && !(data & 0x02)) m_samples->start(1, 1);

	/* DROP BOMB: channel 2 */
	if ((diff & 0x04) && !(data & 0x04)) m_samples->start(2, 2);

	/* SHOOT PISTOL: channel 3 */
	if ((diff & 0x08) && !(data & 0x08)) m_samples->start(3, 3);

	/* MISSILE: channel 4 */
	if ((diff & 0x10) && !(data & 0x10)) m_samples->start(4, 4);

	/* HELICOPTER: channel 5 */
	if ((diff & 0x20) && !(data & 0x20) && !m_samples->playing(5)) m_samples->start(5, 5, true);
	if ((diff & 0x20) &&  (data & 0x20)) m_samples->stop(5);

	/* WHISTLE: channel 6 */
	if ((diff & 0x40) && !(data & 0x40) && !m_samples->playing(6)) m_samples->start(6, 6, true);
	if ((diff & 0x40) &&  (data & 0x40)) m_samples->stop(6);
}


inline void segag80r_state::sega005_update_sound_data()
{
	uint8_t newval = memregion("005")->base()[m_sound_addr];
	uint8_t diff = newval ^ m_sound_data;

	//osd_printf_debug("  [%03X] = %02X\n", m_sound_addr, newval);

	/* latch the new value */
	m_sound_data = newval;

	/* if bit 5 goes high, we reset the timer */
	if ((diff & 0x20) && !(newval & 0x20))
	{
		//osd_printf_debug("Stopping timer\n");
		m_005snd->m_sega005_sound_timer->adjust(attotime::never);
	}

	/* if bit 5 goes low, we start the timer again */
	if ((diff & 0x20) && (newval & 0x20))
	{
		//osd_printf_debug("Starting timer\n");
		m_005snd->m_sega005_sound_timer->adjust(attotime::from_hz(SEGA005_555_TIMER_FREQ), 0, attotime::from_hz(SEGA005_555_TIMER_FREQ));
	}
}


WRITE8_MEMBER(segag80r_state::sega005_sound_b_w)
{
	/*
	       D6: manual timer clock (0->1)
	       D5: 0 = manual timer, 1 = auto timer
	       D4: 1 = hold/reset address counter to 0
	    D3-D0: upper 4 bits of ROM address
	*/
	uint8_t diff = data ^ m_sound_state[1];
	m_sound_state[1] = data;

	//osd_printf_debug("sound[%d] = %02X\n", 1, data);

	/* force a stream update */
	m_005snd->m_sega005_stream->update();

	/* ROM address */
	m_sound_addr = ((data & 0x0f) << 7) | (m_sound_addr & 0x7f);

	/* reset both sound address and square wave counters */
	if (data & 0x10)
	{
		m_sound_addr &= 0x780;
		m_square_state = 0;
	}

	/* manual clock */
	if ((diff & 0x40) && (data & 0x40) && !(data & 0x20) && !(data & 0x10))
		m_sound_addr = (m_sound_addr & 0x780) | ((m_sound_addr + 1) & 0x07f);

	/* update the sound data */
	sega005_update_sound_data();
}



/*************************************
 *
 *  005 custom sound generation
 *
 *************************************/



TIMER_CALLBACK_MEMBER( sega005_sound_device::sega005_auto_timer )
{
	segag80r_state *state = machine().driver_data<segag80r_state>();
	/* force an update then clock the sound address if not held in reset */
	m_sega005_stream->update();
	if ((state->m_sound_state[1] & 0x20) && !(state->m_sound_state[1] & 0x10))
	{
		state->m_sound_addr = (state->m_sound_addr & 0x780) | ((state->m_sound_addr + 1) & 0x07f);
		state->sega005_update_sound_data();
	}
}



/*************************************
 *
 *  Space Odyssey sound hardware
 *
 *************************************/

static const char *const spaceod_sample_names[] =
{
	"*spaceod",
	"fire",         /* 0 */
	"bomb",         /* 1 */
	"eexplode",     /* 2 */
	"pexplode",     /* 3 */
	"warp",         /* 4 */
	"birth",        /* 5 */
	"scoreup",      /* 6 */
	"ssound",       /* 7 */
	"accel",        /* 8 */
	"damaged",      /* 9 */
	"erocket",      /* 10 */
	nullptr
};


MACHINE_CONFIG_START(segag80r_state::spaceod_sound_board)

	/* sound hardware */

	MCFG_DEVICE_ADD("samples", SAMPLES)
	MCFG_SAMPLES_CHANNELS(11)
	MCFG_SAMPLES_NAMES(spaceod_sample_names)
	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "speaker", 0.25)
MACHINE_CONFIG_END


/*************************************
 *
 *  Space Odyssey sound triggers
 *
 *************************************/

WRITE8_MEMBER(segag80r_state::spaceod_sound_w)
{
	uint8_t diff = data ^ m_sound_state[offset];
	m_sound_state[offset] = data;

	switch (offset)
	{
		case 0:
			/* BACK G: channel 0 */
			if ((diff & 0x01) && !(data & 0x01) && !m_samples->playing(0)) m_samples->start(0, 7, true);
			if ((diff & 0x01) &&  (data & 0x01)) m_samples->stop(0);

			/* SHORT EXP: channel 1 */
			if ((diff & 0x04) && !(data & 0x04)) m_samples->start(1, 2);

			/* ACCELERATE: channel 2 */
			if ((diff & 0x10) && !(data & 0x10)) m_samples->start(2, 8);

			/* BATTLE STAR: channel 3 */
			if ((diff & 0x20) && !(data & 0x20)) m_samples->start(3, 10);

			/* D BOMB: channel 4 */
			if ((diff & 0x40) && !(data & 0x40)) m_samples->start(4, 1);

			/* LONG EXP: channel 5 */
			if ((diff & 0x80) && !(data & 0x80)) m_samples->start(5, 3);
			break;

		case 1:
			/* SHOT: channel 6 */
			if ((diff & 0x01) && !(data & 0x01)) m_samples->start(6, 0);

			/* BONUS UP: channel 7 */
			if ((diff & 0x02) && !(data & 0x02)) m_samples->start(7, 6);

			/* WARP: channel 8 */
			if ((diff & 0x08) && !(data & 0x08)) m_samples->start(8, 4);

			/* APPEARANCE UFO: channel 9 */
			if ((diff & 0x40) && !(data & 0x40)) m_samples->start(9, 5);

			/* BLACK HOLE: channel 10 */
			if ((diff & 0x80) && !(data & 0x80)) m_samples->start(10, 9);
			break;
	}
}



/*************************************
 *
 *  Monster Bash sound hardware
 *
 *************************************/

/*
    Monster Bash

    The Sound Board is a fairly complex mixture of different components.
    An 8255A-5 controls the interface to/from the sound board.
    Port A connects to a TMS3617 (basic music synthesizer) circuit.
    Port B connects to two sounds generated by discrete circuitry.
    Port C connects to a NEC7751 (8048 CPU derivative) to control four "samples".
*/

DEFINE_DEVICE_TYPE(MONSTERB_SOUND, monsterb_sound_device, "monsterb_sound", "Monster Bash Sound Board")

static const char *const monsterb_sample_names[] =
{
	"*monsterb",
	"zap",
	"jumpdown",
	nullptr
};

monsterb_sound_device::monsterb_sound_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
	: device_t(mconfig, MONSTERB_SOUND, tag, owner, clock)
	, m_audiocpu(*this, "audiocpu")
	, m_audiocpu_region(*this, "n7751")
	, m_music(*this, "music")
	, m_samples(*this, "samples")
	, m_i8243(*this, "i8243")
{
}

void monsterb_sound_device::device_start()
{
	save_item(NAME(m_n7751_command));
	save_item(NAME(m_n7751_busy));
	save_item(NAME(m_sound_state));
	save_item(NAME(m_sound_addr));
}

/*************************************
 *
 *  Machine driver
 *
 *************************************/

MACHINE_CONFIG_START(monsterb_sound_device::device_add_mconfig)
	/* basic machine hardware */
	MCFG_DEVICE_ADD(m_audiocpu, N7751, 6000000)
	MCFG_MCS48_PORT_T1_IN_CB(GND) // labelled as "TEST", connected to ground
	MCFG_MCS48_PORT_P2_IN_CB(READ8(*this, monsterb_sound_device, n7751_command_r))
	MCFG_MCS48_PORT_BUS_IN_CB(READ8(*this, monsterb_sound_device, n7751_rom_r))
	MCFG_MCS48_PORT_P1_OUT_CB(WRITE8("dac", dac_byte_interface, data_w))
	MCFG_MCS48_PORT_P2_OUT_CB(WRITE8(*this, monsterb_sound_device, n7751_p2_w))
	MCFG_MCS48_PORT_PROG_OUT_CB(WRITELINE(m_i8243, i8243_device, prog_w))

	MCFG_DEVICE_ADD(m_i8243, I8243, 0)
	MCFG_I8243_READHANDLER(CONSTANT(0))
	MCFG_I8243_WRITEHANDLER(WRITE8(*this, monsterb_sound_device, n7751_rom_control_w))

	MCFG_DEVICE_ADD(m_samples, SAMPLES)
	MCFG_SAMPLES_CHANNELS(2)
	MCFG_SAMPLES_NAMES(monsterb_sample_names)
	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "speaker", 0.25)

	MCFG_TMS36XX_ADD(m_music, 247)
	MCFG_TMS36XX_TYPE(TMS3617)
	MCFG_TMS36XX_DECAY_TIMES(0.5, 0.5, 0.5, 0.5, 0.5, 0.5)
	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "speaker", 0.5)

	MCFG_DEVICE_ADD("dac", DAC_8BIT_R2R, 0) MCFG_SOUND_ROUTE(ALL_OUTPUTS, "speaker", 0.5) // 50K (R91-97)/100K (R98-106) ladder network
	MCFG_DEVICE_ADD("vref", VOLTAGE_REGULATOR, 0) MCFG_VOLTAGE_REGULATOR_OUTPUT(5.0)
	MCFG_SOUND_ROUTE(0, "dac", 1.0, DAC_VREF_POS_INPUT) MCFG_SOUND_ROUTE(0, "dac", -1.0, DAC_VREF_NEG_INPUT)

	SPEAKER(config, "speaker").front_center();
MACHINE_CONFIG_END


/*************************************
 *
 *  TMS3617 access
 *
 *************************************/

WRITE8_MEMBER(monsterb_sound_device::sound_a_w)
{
	/* Lower four data lines get decoded into 13 control lines */
	m_music->tms36xx_note_w(0, data & 15);

	/* Top four data lines address an 82S123 ROM that enables/disables voices */
	int enable_val = machine().root_device().memregion("prom")->base()[(data & 0xF0) >> 4];
	m_music->tms3617_enable_w(enable_val >> 2);
}



/*************************************
 *
 *  Discrete sound triggers
 *
 *************************************/

WRITE8_MEMBER(monsterb_sound_device::sound_b_w)
{
	uint8_t diff = data ^ m_sound_state[1];
	m_sound_state[1] = data;

	/* SHOT: channel 0 */
	if ((diff & 0x01) && !(data & 0x01)) m_samples->start(0, 0);

	/* DIVE: channel 1 */
	if ((diff & 0x02) && !(data & 0x02)) m_samples->start(1, 1);

	/* TODO: D7 on Port B might affect TMS3617 output (mute?) */
}



/*************************************
 *
 *  N7751 connections
 *
 *************************************/

READ8_MEMBER(monsterb_sound_device::n7751_status_r)
{
	return m_n7751_busy << 4;
}


WRITE8_MEMBER(monsterb_sound_device::n7751_command_w)
{
	/*
	    Z80 7751 control port

	    D0-D2 = connected to 7751 port C
	    D3    = /INT line
	*/
	m_n7751_command = data & 0x07;
	m_audiocpu->set_input_line(0, ((data & 0x08) == 0) ? ASSERT_LINE : CLEAR_LINE);
	machine().scheduler().boost_interleave(attotime::zero, attotime::from_usec(100));
}


WRITE8_MEMBER(monsterb_sound_device::n7751_rom_control_w)
{
	/* P4 - address lines 0-3 */
	/* P5 - address lines 4-7 */
	/* P6 - address lines 8-11 */
	/* P7 - ROM selects */
	switch (offset)
	{
		case 0:
			m_sound_addr = (m_sound_addr & ~0x00f) | ((data & 0x0f) << 0);
			break;

		case 1:
			m_sound_addr = (m_sound_addr & ~0x0f0) | ((data & 0x0f) << 4);
			break;

		case 2:
			m_sound_addr = (m_sound_addr & ~0xf00) | ((data & 0x0f) << 8);
			break;

		case 3:
			m_sound_addr &= 0xfff;
			{
				int numroms = m_audiocpu_region->bytes() / 0x1000;
				if (!(data & 0x01) && numroms >= 1) m_sound_addr |= 0x0000;
				if (!(data & 0x02) && numroms >= 2) m_sound_addr |= 0x1000;
				if (!(data & 0x04) && numroms >= 3) m_sound_addr |= 0x2000;
				if (!(data & 0x08) && numroms >= 4) m_sound_addr |= 0x3000;
			}
			break;
	}
}


READ8_MEMBER(monsterb_sound_device::n7751_rom_r)
{
	/* read from BUS */
	return m_audiocpu_region->base()[m_sound_addr];
}


READ8_MEMBER(monsterb_sound_device::n7751_command_r)
{
	/* read from P2 - 8255's PC0-2 connects to 7751's S0-2 (P24-P26 on an 8048) */
	/* bit 0x80 is an alternate way to control the sample on/off; doesn't appear to be used */
	return 0x80 | ((m_n7751_command & 0x07) << 4);
}


WRITE8_MEMBER(monsterb_sound_device::n7751_p2_w)
{
	/* write to P2; low 4 bits go to 8243 */
	m_i8243->p2_w(space, offset, data & 0x0f);

	/* output of bit $80 indicates we are ready (1) or busy (0) */
	/* no other outputs are used */
	m_n7751_busy = data >> 7;
}