summaryrefslogtreecommitdiffstatshomepage
path: root/src/emu/bus/isa/omti8621.c
blob: 8f9b126d053bb061e3a54d3d401c8ce314de00a9 (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
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
/*
 * omti8621.c - SMS OMTI 8621 disk controller (for Apollo DN3x00)
 *
 *  Created on: August 30, 2010
 *      Author: Hans Ostermeyer
 *
 *  Converted to ISA device by R. Belmont
 *
 *  Released for general non-commercial use under the MAME license
 *  Visit http://mamedev.org for licensing and usage restrictions.
 *
 *  see also:
 *  * http://www.bitsavers.org/pdf/sms/pc/OMTI_AT_Controller_Series_Jan87.pdf
 */

#define VERBOSE 0

static int verbose = VERBOSE;

#include "omti8621.h"
#include "image.h"
#include "formats/pc_dsk.h"
#include "formats/naslite_dsk.h"
#include "formats/apollo_dsk.h"

#define LOG(x)  { logerror ("%s: ", cpu_context(this)); logerror x; logerror ("\n"); }
#define LOG1(x) { if (verbose > 0) LOG(x)}
#define LOG2(x) { if (verbose > 1) LOG(x)}
#define LOG3(x) { if (verbose > 2) LOG(x)}

#define OMTI_DISK_SECTOR_SIZE 1056

#define OMTI_DISK_TYPE_155_MB 0x607 // Micropolis 1355 (170 MB Dtype = 607)
#define OMTI_DISK_TYPE_348_MB 0x604 // Maxtor EXT-4380-E (380 MB Dtype = 604)
#define OMTI_DISK_TYPE_DEFAULT OMTI_DISK_TYPE_348_MB // new disks will have this type (and size)

#define OMTI_MAX_BLOCK_COUNT 32

#define OMTI_DISK0_TAG "omti_disk0"
#define OMTI_DISK1_TAG "omti_disk1"

#define OMTI_FDC_TAG "omti_fdc"

#define OMTI_CPU_REGION "omti_cpu"
#define OMTI_BIOS_REGION "omti_bios"

// forward declaration of image class
extern const device_type OMTI_DISK;

class omti_disk_image_device :  public device_t,
								public device_image_interface
{
public:
	// construction/destruction
	omti_disk_image_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock);

	// image-level overrides
	virtual iodevice_t image_type() const { return IO_HARDDISK; }

	virtual bool is_readable()  const { return 1; }
	virtual bool is_writeable() const { return 1; }
	virtual bool is_creatable() const { return 1; }
	virtual bool must_be_loaded() const { return 0; }
	virtual bool is_reset_on_load() const { return 0; }
	virtual const char *image_interface() const { return NULL; }
	virtual const char *file_extensions() const { return "awd"; }
	virtual const option_guide *create_option_guide() const { return NULL; }

	virtual bool call_create(int format_type, option_resolution *format_options);
protected:
	// device-level overrides
	virtual void device_config_complete();
	virtual void device_start();
	virtual void device_reset();

	void omti_disk_config(UINT16 disk_type);
public:
	UINT16 m_type;
	UINT16 m_cylinders;
	UINT16 m_heads;
	UINT16 m_sectors;
	UINT32 m_sectorbytes;
	UINT32 m_sector_count;

	device_image_interface *m_image;

	// configuration data
	UINT8 m_config_data[10];

	// ESDI defect list data
	UINT8 m_esdi_defect_list[256];
};

/*
 * I/O register offsets
 */

#define OMTI_PORT_DATA_IN    0x00    /* read, 8-bit */
#define OMTI_PORT_DATA_OUT   0x00    /* write, 8-bit */
#define OMTI_PORT_STATUS     0x01    /* read, 8-bit */
#define OMTI_PORT_RESET      0x01    /* write, 8-bit */
#define OMTI_PORT_CONFIG     0x02    /* read, 8-bit */
#define OMTI_PORT_SELECT     0x02    /* write, 8-bit */
#define OMTI_PORT_MASK       0x03    /* write only, 8-bit */

// port status

#define OMTI_STATUS_REQ  0x01 // Request (1 = request transfer of data via data in/out register)
#define OMTI_STATUS_IO   0x02 // In/Out (1 = direction of transfer is from controller to host)
#define OMTI_STATUS_CD   0x04 // Command/Data ( 1 = byte transfered is command or status byte)
#define OMTI_STATUS_BUSY 0x08 // Busy (0 = controller is idle, 1 = controller selected)
#define OMTI_STATUS_DREQ 0x10 // Data Request (0 = no DMA request, 1 = DMA cycle requested)
#define OMTI_STATUS_IREQ 0x20 // Interrupt Request (0 = no interrupt, 1 = command complete)
#define OMTI_STATUS_NU6  0x40 // not used
#define OMTI_STATUS_NU7  0x80 // not used

#define OMTI_CONFIG_W23  0x01 // jumper W23
#define OMTI_CONFIG_W22  0x02 // jumper W22
#define OMTI_CONFIG_W21  0x04 // jumper W21
#define OMTI_CONFIG_W20  0x08 // jumper W20

#define OMTI_MASK_DMAE  0x01 // DMA enable
#define OMTI_MASK_INTE  0x02 // Interrupt enable

#define OMTI_COMMAND_STATUS_ERROR 0x02 // error bit
#define OMTI_COMMAND_STATUS_LUN 0x20 // drive 0 is 0

#define OMTI_SENSE_CODE_NO_ERROR 0x00
#define OMTI_SENSE_CODE_DRIVE_NOT_READY 0x04
#define OMTI_SENSE_CODE_ADDRESS_VALID 0x80
#define OMTI_SENSE_CODE_SECTOR_NOT_FOUND 0x14
#define OMTI_SENSE_CODE_ECC_ERROR 0x11
#define OMTI_SENSE_CODE_BAD_TRACK 0x19
#define OMTI_SENSE_CODE_ALTERNATE_TRACK 0x1C
#define OMTI_SENSE_CODE_INVALID_COMMAND 0x20
#define OMTI_SENSE_CODE_ILLEGAL_ADDRESS 0x21

enum {
	OMTI_STATE_RESET,
	OMTI_STATE_IDLE,
	OMTI_STATE_SELECTION,
	OMTI_STATE_COMMAND,
	OMTI_STATE_DATA,
	OMTI_STATE_STATUS,
};

// OMTI commands

#define OMTI_CMD_TEST_DRIVE_READY 0x00
#define OMTI_CMD_RECALIBRATE 0x01

#define OMTI_CMD_REQUEST_SENSE 0x03
#define OMTI_CMD_FORMAT_DRIVEUNIT 0x04
#define OMTI_CMD_READ_VERIFY 0x05
#define OMTI_CMD_FORMAT_TRACK 0x06
#define OMTI_CMD_FORMAT_BAD_TRACK 0x07
#define OMTI_CMD_READ 0x08

#define OMTI_CMD_WRITE 0x0a
#define OMTI_CMD_SEEK 0x0b

#define OMTI_CMD_READ_SECTOR_BUFFER 0x0e
#define OMTI_CMD_WRITE_SECTOR_BUFFER 0x0f

#define OMTI_CMD_ASSIGN_ALTERNATE_TRACK 0x11

#define OMTI_CMD_READ_DATA_TO_BUFFER 0x1e
#define OMTI_CMD_WRITE_DATA_FROM_BUFFER 0x1f
#define OMTI_CMD_COPY 0x20

#define OMTI_CMD_READ_ESDI_DEFECT_LIST 0x37

#define OMTI_CMD_RAM_DIAGNOSTICS 0xe0
#define OMTI_CMD_CONTROLLER_INT_DIAGNOSTIC 0xe4
#define OMTI_CMD_READ_LONG 0xe5
#define OMTI_CMD_WRITE_LONG 0xe6

#define OMTI_CMD_READ_CONFIGURATION 0xec
#define OMTI_CMD_INVALID_COMMAND 0xff

/***************************************************************************
 cpu_context - return a string describing the current CPU context
 ***************************************************************************/

static const char *cpu_context(const device_t *device) {
	static char statebuf[64]; /* string buffer containing state description */

	device_t *cpu = device->machine().firstcpu;

	/* if we have an executing CPU, output data */
	if (cpu != NULL) {
		osd_ticks_t t = osd_ticks();
		int s = t / osd_ticks_per_second();
		int ms = (t % osd_ticks_per_second()) / 1000;

		sprintf(statebuf, "%d.%03d %s pc=%08x - %s", s, ms, cpu->tag(),
				cpu->safe_pcbase(), device->tag());
	} else {
		strcpy(statebuf, "(no context)");
	}
	return statebuf;
}

static SLOT_INTERFACE_START( pc_hd_floppies )
	SLOT_INTERFACE( "525hd", FLOPPY_525_HD )
	SLOT_INTERFACE( "35hd", FLOPPY_35_HD )
	SLOT_INTERFACE( "525dd", FLOPPY_525_DD )
	SLOT_INTERFACE( "35dd", FLOPPY_35_DD )
SLOT_INTERFACE_END

MACHINE_CONFIG_FRAGMENT( omti_disk )
	MCFG_DEVICE_ADD(OMTI_DISK0_TAG, OMTI_DISK, 0)
	MCFG_DEVICE_ADD(OMTI_DISK1_TAG, OMTI_DISK, 0)

	MCFG_PC_FDC_AT_ADD(OMTI_FDC_TAG)
	MCFG_PC_FDC_INTRQ_CALLBACK(WRITELINE(omti8621_device, fdc_irq_w))
	MCFG_PC_FDC_DRQ_CALLBACK(WRITELINE(omti8621_device, fdc_drq_w))
	MCFG_FLOPPY_DRIVE_ADD(OMTI_FDC_TAG":0", pc_hd_floppies, "525hd", omti8621_device::floppy_formats)
	MCFG_FLOPPY_DRIVE_ADD(OMTI_FDC_TAG":1", pc_hd_floppies, "525hd", omti8621_device::floppy_formats)
MACHINE_CONFIG_END

FLOPPY_FORMATS_MEMBER( omti8621_device::floppy_formats )
	FLOPPY_APOLLO_FORMAT,
	FLOPPY_PC_FORMAT,
	FLOPPY_NASLITE_FORMAT
FLOPPY_FORMATS_END

// this card has two EPROMs: a program for the on-board Z8 CPU,
// and a PC BIOS to make the card bootable on a PC.
// we have the Z8 program, we still need the PC BIOS.
ROM_START( omti8621 )
	ROM_REGION(0x4000, OMTI_CPU_REGION, 0)  // disassembles fine as Z8 code
	ROM_LOAD( "omti_8621_102640-b.bin", 0x000000, 0x004000, CRC(e6f20dbb) SHA1(cf1990ad72eac6b296485410f5fa3309a0d6d078) )

	ROM_REGION(0x1000, OMTI_BIOS_REGION, 0)
	ROM_LOAD("omti_bios", 0x0000, 0x1000, NO_DUMP)
ROM_END

static INPUT_PORTS_START( omti_port )
	PORT_START("IO_BASE")
	PORT_DIPNAME( 0x07, 0x04, "ESDI I/O base")
	PORT_DIPSETTING(    0x00, "0320h" )
	PORT_DIPSETTING(    0x01, "0324h" )
	PORT_DIPSETTING(    0x02, "0328h" )
	PORT_DIPSETTING(    0x03, "032Ch" )
	PORT_DIPSETTING(    0x04, "01A0h" )
	PORT_DIPSETTING(    0x05, "01A4h" )
	PORT_DIPSETTING(    0x06, "01A8h" )
	PORT_DIPSETTING(    0x07, "01ACh" )
	PORT_DIPNAME( 0x08, 0x00, "Floppy I/O base")
	PORT_DIPSETTING(    0x00, "03F0h" )
	PORT_DIPSETTING(    0x01, "0370h" )

	PORT_START("BIOS_OPTS")
	PORT_DIPNAME( 0x01, 0x00, "BIOS control")
	PORT_DIPSETTING(    0x00, "Disabled" )
	PORT_DIPSETTING(    0x01, "Enabled" )
	PORT_DIPNAME( 0x02, 0x00, "BIOS base")
	PORT_DIPSETTING(    0x00, "C8000h" )
	PORT_DIPSETTING(    0x01, "CA000h" )
INPUT_PORTS_END

machine_config_constructor omti8621_device::device_mconfig_additions() const
{
	return MACHINE_CONFIG_NAME( omti_disk );
}

const rom_entry *omti8621_device::device_rom_region() const
{
	return ROM_NAME( omti8621 );
}

ioport_constructor omti8621_device::device_input_ports() const
{
	return INPUT_PORTS_NAME( omti_port );
}

/*-------------------------------------------------
    device start callback
-------------------------------------------------*/

void omti8621_device::device_start()
{
	set_isa_device();

	m_installed = false;

	sector_buffer.resize(OMTI_DISK_SECTOR_SIZE*OMTI_MAX_BLOCK_COUNT);

	m_timer = timer_alloc(0, NULL);

	our_disks[0] = subdevice<omti_disk_image_device>(OMTI_DISK0_TAG);
	our_disks[1] = subdevice<omti_disk_image_device>(OMTI_DISK1_TAG);
}

/*-------------------------------------------------
    device reset callback
-------------------------------------------------*/

void omti8621_device::device_reset()
{
	static const int io_bases[8] = { 0x320, 0x324, 0x328, 0x32c, 0x1a0, 0x1a4, 0x1a8, 0x1ac };

	LOG2(("device_reset_omti8621"));

	// you can't read I/O ports in device_start() even if they're required_ioport<> in your class!
	if (!m_installed)
	{
		int esdi_base = io_bases[m_iobase->read() & 7];

		// install the ESDI ports
		m_isa->install16_device(esdi_base, esdi_base + 7, 0, 0, read16_delegate(FUNC(omti8621_device::read), this), write16_delegate(FUNC(omti8621_device::write), this));

		// and the onboard AT FDC ports
		if (m_iobase->read() & 8)
		{
			m_isa->install_device(0x0370, 0x0377, *m_fdc, &pc_fdc_interface::map);
		}
		else
		{
			m_isa->install_device(0x03f0, 0x03f7, *m_fdc, &pc_fdc_interface::map);
		}

		m_isa->set_dma_channel(2, this, TRUE);

		m_installed = true;
	}

	set_jumper(our_disks[0]->m_type);

	// should go from reset to idle after 100 us
	// state->omti_state = OMTI_STATE_RESET;
	omti_state = OMTI_STATE_IDLE;

	status_port =  OMTI_STATUS_NU6 | OMTI_STATUS_NU7;
	config_port = ~jumper;
	mask_port = 0;

	// default the sector data buffer with model and status information
	// (i.e. set sector data buffer for cmd=0x0e READ SECTOR BUFFER)

	memset(&sector_buffer[0], 0, OMTI_DISK_SECTOR_SIZE);
	memcpy(&sector_buffer[0], "8621VB.4060487xx", 0x10);
	sector_buffer[0x10] = 0; // ROM Checksum error
	sector_buffer[0x11] = 0; // Processor Register error
	sector_buffer[0x12] = 0; // Buffer RAM error
	sector_buffer[0x13] = 0; // Sequencer Register File error
	sector_buffer[0x14] = 0xc0; // 32K buffer size
	// TODO: add missing Default values for LUN 0, 1 and 3

	command_length = 0;
	command_index = 0;
	command_status = 0;

	data_index = 0;
	data_length = 0;

	clear_sense_data();

	diskaddr_ecc_error = 0;
	diskaddr_format_bad_track = 0;
	alternate_track_address[0] = 0;
	alternate_track_address[1] = 0;
}

const device_type ISA16_OMTI8621 = &device_creator<omti8621_device>;

omti8621_device::omti8621_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
	: device_t(mconfig, ISA16_OMTI8621, "OMTI 8621 ESDI/floppy controller", tag, owner, clock, "omti8621", __FILE__),
	device_isa16_card_interface(mconfig, *this),
	m_fdc(*this, OMTI_FDC_TAG),
	m_iobase(*this, "IO_BASE"),
	m_biosopts(*this, "BIOS_OPTS")
{
}

//-------------------------------------------------
//  device_config_complete - perform any
//  operations now that the configuration is
//  complete
//-------------------------------------------------

void omti8621_device::device_config_complete()
{
}

/*-------------------------------------------------
 set_interrupt - update the IRQ state
 -------------------------------------------------*/

void omti8621_device::set_interrupt(enum line_state line_state)
{
	LOG2(("set_interrupt: status_port=%x, line_state %d", status_port, line_state));
	m_isa->irq14_w(line_state);
}

void omti8621_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
{
	set_interrupt(ASSERT_LINE);
}

/***************************************************************************
 clear_sense_data - clear the sense data
 ***************************************************************************/

void omti8621_device::clear_sense_data() {
	LOG2(("clear_sense_data"));
	memset(sense_data, 0, sizeof(sense_data));
}

/***************************************************************************
 set_sense_data - set the sense data from code and command descriptor block
 ***************************************************************************/

void omti8621_device::set_sense_data(UINT8 code, const UINT8 * cdb) {
	LOG2(("set_sense_data code=%x", code));
	sense_data[0]=code;
	sense_data[1]=cdb[1];
	sense_data[2]=cdb[2];
	sense_data[3]=cdb[3];
}

/***************************************************************************
 set_configuration_data - set the configuration data for drive lun
 ***************************************************************************/

void omti8621_device::set_configuration_data(UINT8 lun) {
	LOG2(("set_configuration_data lun=%x", lun));

	// initialize the configuration data
	omti_disk_image_device *disk = our_disks[lun];

	disk->m_config_data[0] = (disk->m_cylinders - 1) >> 8; // Number of Cylinders (MSB)
	disk->m_config_data[1] = (disk->m_cylinders - 1) & 0xff; // Number of Cylinders (LSB) (-1)
	disk->m_config_data[2] = disk->m_heads - 1; // Number of Heads (-1)
	disk->m_config_data[3] = disk->m_sectors - 1; // Number of Sectors (-1)
	disk->m_config_data[4] = 0x02; // Drive Configuration Word (MSB)
	disk->m_config_data[5] = 0x44; // Drive Configuration Word (LSB)
	disk->m_config_data[6] = 0x00; // ISG AFTER INDEX
	disk->m_config_data[7] = 0x00; // PLO SYN Field (ID)
	disk->m_config_data[8] = 0x00; // PLO SYN Field (DATA)
	disk->m_config_data[9] = 0x00; // ISG AFTER SECTOR
}

/***************************************************************************
 get_lun - get logical unit number from a command descriptor block (in bit 5)
 ***************************************************************************/

UINT8 omti8621_device::get_lun(const UINT8 * cdb)
{
	return   (cdb[1] & 0x20) >> 5;
}

/***************************************************************************
 check_disk_address - check disk address, set sense data and return true for no error
 ***************************************************************************/

UINT8 omti8621_device::check_disk_address(const UINT8 *cdb)
{
	UINT8 sense_code = OMTI_SENSE_CODE_NO_ERROR;
	UINT8 lun = get_lun(cdb);
	UINT16 head = cdb[1] & 0x1f;
	UINT16 sector = cdb[2] & 0x3f;
	UINT32 cylinder = cdb[3] + ((cdb[2] & 0xc0) << 2) + ((cdb[1] & 0x80) << 3);
	UINT8 block_count = cdb[4];
	omti_disk_image_device *disk = our_disks[lun];

	UINT32 disk_track = cylinder * disk->m_heads + head;
	UINT32 disk_addr = (disk_track * disk->m_sectors) + sector;

	if (block_count > OMTI_MAX_BLOCK_COUNT) {
		LOG(("########### check_disk_address: unexpected block count %x", block_count));
		sense_code = OMTI_SENSE_CODE_ILLEGAL_ADDRESS | OMTI_SENSE_CODE_ADDRESS_VALID;
	}

	if (lun > OMTI_MAX_LUN) {
		sense_code = OMTI_SENSE_CODE_DRIVE_NOT_READY;
	} else  if (!disk->m_image->exists()) {
		sense_code = OMTI_SENSE_CODE_DRIVE_NOT_READY;
	} else  if (sector >= OMTI_MAX_BLOCK_COUNT) {
		sense_code = OMTI_SENSE_CODE_ILLEGAL_ADDRESS | OMTI_SENSE_CODE_ADDRESS_VALID;
	} else if (head >= disk->m_heads) {
		sense_code = OMTI_SENSE_CODE_ILLEGAL_ADDRESS | OMTI_SENSE_CODE_ADDRESS_VALID;
	} else if (cylinder >= disk->m_cylinders) {
		sense_code = OMTI_SENSE_CODE_ILLEGAL_ADDRESS | OMTI_SENSE_CODE_ADDRESS_VALID;
	} else if ( disk_track == diskaddr_format_bad_track && disk_track != 0) {
		sense_code = OMTI_SENSE_CODE_BAD_TRACK;
	} else if (disk_addr == diskaddr_ecc_error && disk_addr != 0) {
		sense_code = OMTI_SENSE_CODE_ECC_ERROR;
	} else if (disk_track == alternate_track_address[1] && disk_track != 0) {
		sense_code = OMTI_SENSE_CODE_ALTERNATE_TRACK;
	}

	if (sense_code == OMTI_SENSE_CODE_NO_ERROR) {
		clear_sense_data();
	} else {
		command_status |= OMTI_COMMAND_STATUS_ERROR;
		set_sense_data(sense_code, cdb);
	}
	return sense_code == OMTI_SENSE_CODE_NO_ERROR;
}

/***************************************************************************
 get_disk_track - get disk track from a command descriptor block
 ***************************************************************************/

UINT32 omti8621_device::get_disk_track(const UINT8 * cdb) {
	UINT8 lun = get_lun(cdb);
	UINT16 head = cdb[1] & 0x1f;
	UINT32 cylinder = cdb[3] + ((cdb[2] & 0xc0) << 2) + ((cdb[1] & 0x80) << 3);
	return cylinder * our_disks[lun]->m_heads + head;
}

/***************************************************************************
 get_disk_address - get disk address from a command descriptor block
 ***************************************************************************/

UINT32 omti8621_device::get_disk_address(const UINT8 * cdb) {
	UINT8 lun = get_lun(cdb);
	UINT16 sector = cdb[2] & 0x3f;
	return get_disk_track(cdb) * our_disks[lun]->m_sectors + sector;
}

/***************************************************************************
 set_data_transfer - setup for data transfer from/to data
 ***************************************************************************/

void omti8621_device::set_data_transfer(UINT8 *data, UINT16 length)
{
	// set controller for read data transfer
	omti_state = OMTI_STATE_DATA;
	status_port |= OMTI_STATUS_REQ | OMTI_STATUS_IO | OMTI_STATUS_BUSY;
	status_port &= ~OMTI_STATUS_CD;

	data_buffer = data;
	data_length = length;
	data_index = 0;
}

/***************************************************************************
 read_sectors_from_disk - read sectors starting at diskaddr into sector_buffer
 ***************************************************************************/

void omti8621_device::read_sectors_from_disk(INT32 diskaddr, UINT8 count, UINT8 lun)
{
	UINT8 *data_buffer = &sector_buffer[0];
	device_image_interface *image = our_disks[lun]->m_image;

	while (count-- > 0) {
		LOG2(("read_sectors_from_disk lun=%d diskaddr=%x", lun, diskaddr));

		image->fseek( diskaddr * OMTI_DISK_SECTOR_SIZE, SEEK_SET);
		image->fread( data_buffer, OMTI_DISK_SECTOR_SIZE);

		diskaddr++;
		data_buffer += OMTI_DISK_SECTOR_SIZE;
	}
}

/***************************************************************************
 write_sectors_to_disk - write sectors starting at diskaddr from sector_buffer
 ***************************************************************************/

void omti8621_device::write_sectors_to_disk(INT32 diskaddr, UINT8 count, UINT8 lun)
{
	UINT8 *data_buffer = &sector_buffer[0];
	device_image_interface *image = our_disks[lun]->m_image;

	while (count-- > 0) {
		LOG2(("write_sectors_to_disk lun=%d diskaddr=%x", lun, diskaddr));

		image->fseek( diskaddr * OMTI_DISK_SECTOR_SIZE, SEEK_SET);
		image->fwrite( data_buffer, OMTI_DISK_SECTOR_SIZE);

		if (diskaddr == diskaddr_ecc_error) {
			// reset previous ECC error
			diskaddr_ecc_error = 0;
		}

		diskaddr++;
		data_buffer += OMTI_DISK_SECTOR_SIZE;
	}
}

/***************************************************************************
 copy_sectors - copy sectors
 ***************************************************************************/

void omti8621_device::copy_sectors(INT32 dst_addr, INT32 src_addr, UINT8 count, UINT8 lun)
{
	device_image_interface *image = our_disks[lun]->m_image;

	LOG2(("copy_sectors lun=%d src_addr=%x dst_addr=%x count=%x", lun, src_addr, dst_addr, count));

	while (count-- > 0) {
		image->fseek( src_addr * OMTI_DISK_SECTOR_SIZE, SEEK_SET);
		image->fread( &sector_buffer[0], OMTI_DISK_SECTOR_SIZE);

		image->fseek( dst_addr * OMTI_DISK_SECTOR_SIZE, SEEK_SET);
		image->fwrite( &sector_buffer[0], OMTI_DISK_SECTOR_SIZE);

		if (dst_addr == diskaddr_ecc_error) {
			// reset previous ECC error
			diskaddr_ecc_error = 0;
		}

		src_addr++;
		dst_addr++;
	}
}

/***************************************************************************
 format track - format a track
 ***************************************************************************/

void omti8621_device::format_track(const UINT8 * cdb)
{
	UINT8 lun = get_lun(cdb);
	UINT32 disk_addr = get_disk_address(cdb);
	UINT32 disk_track = get_disk_track(cdb);

	if (diskaddr_ecc_error == disk_addr) {
		// reset previous ECC error
		diskaddr_ecc_error = 0;
	}

	if (diskaddr_format_bad_track == disk_track) {
		// reset previous bad track formatting
		diskaddr_format_bad_track = 0;
	}

	if (alternate_track_address[0] == disk_track) {
		// reset source of alternate track address
		alternate_track_address[0] = 0;
	}

	if (alternate_track_address[1] == disk_track) {
		// reset alternate track address
		alternate_track_address[1] = 0;
	}

	if (check_disk_address(cdb) ) {
		if ((cdb[5] & 0x40) == 0) {
			memset(&sector_buffer[0], 0x6C, OMTI_DISK_SECTOR_SIZE * our_disks[lun]->m_sectors);
		}
		write_sectors_to_disk(disk_addr, our_disks[lun]->m_sectors, lun);
	}

}

/***************************************************************************
 set_esdi_defect_list - setup the (emty) ESDI defect list
 ***************************************************************************/

void omti8621_device::set_esdi_defect_list(UINT8 lun, UINT8 head)
{
	omti_disk_image_device *disk = our_disks[lun];

	memset(disk->m_esdi_defect_list, 0, sizeof(disk->m_esdi_defect_list));
	disk->m_esdi_defect_list[0] = 1; // month
	disk->m_esdi_defect_list[1] = 1; // day
	disk->m_esdi_defect_list[2] = 90; // year
	disk->m_esdi_defect_list[3] = head;
	memset(disk->m_esdi_defect_list+6, 0xff, 5); // end of defect list
}

/***************************************************************************
 log_command - log command from a command descriptor block
 ***************************************************************************/

void omti8621_device::log_command(const UINT8 cdb[], const UINT16 cdb_length)
{
	if (verbose > 0) {
		int i;
		logerror("%s: OMTI command ", cpu_context(this));
		switch (cdb[0]) {
		case OMTI_CMD_TEST_DRIVE_READY: // 0x00
			logerror("Test Drive Ready");
			break;
		case OMTI_CMD_RECALIBRATE: // 0x01
			logerror("Recalibrate");
			break;
		case OMTI_CMD_REQUEST_SENSE: // 0x03
			logerror("Request Sense");
			break;
		case OMTI_CMD_READ_VERIFY: // 0x05
			logerror("Read Verify");
			break;
		case OMTI_CMD_FORMAT_TRACK: // 0x06
			logerror("Format Track");
			break;
		case OMTI_CMD_FORMAT_BAD_TRACK: // 0x07
			logerror("Format Bad Track");
			break;
		case OMTI_CMD_READ: // 0x08
			logerror("Read");
			break;
		case OMTI_CMD_WRITE: // 0x0A
			logerror("Write");
			break;
		case OMTI_CMD_SEEK: // 0x0B
			logerror("Seek");
			break;
		case OMTI_CMD_READ_SECTOR_BUFFER: // 0x0E
			logerror("Read Sector Buffer");
			break;
		case OMTI_CMD_WRITE_SECTOR_BUFFER: // 0x0F
			logerror("Write Sector Buffer");
			break;
		case OMTI_CMD_ASSIGN_ALTERNATE_TRACK: // 0x11
			logerror("Assign Alternate Track");
			break;
		case OMTI_CMD_READ_DATA_TO_BUFFER: // 0x1E
			logerror("Read Data to Buffer");
			break;
		case OMTI_CMD_WRITE_DATA_FROM_BUFFER: // 0x1F
			logerror("Write Data from Buffer");
			break;
		case OMTI_CMD_COPY: // 0x20
			logerror("Copy");
			break;
		case OMTI_CMD_READ_ESDI_DEFECT_LIST: // 0x37
			logerror("Read ESDI Defect List");
			break;
		case OMTI_CMD_RAM_DIAGNOSTICS: // 0xE0
			logerror("RAM. Diagnostic");
			break;
		case OMTI_CMD_CONTROLLER_INT_DIAGNOSTIC: // 0xE4
			logerror("Controller Int. Diagnostic");
			break;
		case OMTI_CMD_READ_LONG: // 0xE5
			logerror("Read Long");
			break;
		case OMTI_CMD_WRITE_LONG: // 0xE6
			logerror("Write Long");
			break;
		case OMTI_CMD_READ_CONFIGURATION: // 0xEC
			logerror("Read Configuration");
			break;
		case OMTI_CMD_INVALID_COMMAND: // 0xFF
			logerror("Invalid Command");
			break;
		default:
			logerror("!!! Unexpected Command !!!");
		}
//      logerror(" (%02x, length=%02x)", cdb[0], cdb_length);
		for (i = 0; i < cdb_length; i++) {
			logerror(" %02x", cdb[i]);
		}

		switch (cdb[0]) {
		case OMTI_CMD_READ_VERIFY: // 0x05
		case OMTI_CMD_READ: // 0x08
		case OMTI_CMD_WRITE: // 0x0a
		case OMTI_CMD_SEEK: // 0x0b
		case OMTI_CMD_READ_DATA_TO_BUFFER: // 0x1E
		case OMTI_CMD_WRITE_DATA_FROM_BUFFER: // 0x1F
		case OMTI_CMD_COPY: // 0x20
			logerror(" (diskaddr=%x count=%x)", get_disk_address(cdb), cdb[4]);
			break;
		}
		logerror("\n");
	}
}

/***************************************************************************
 log_data - log data in the common data buffer
 ***************************************************************************/

void omti8621_device::log_data()
{
	if (verbose > 0) {
		int i;
		logerror("%s: OMTI data (length=%02x)", cpu_context(this),
				data_length);
		for (i = 0; i < data_length && i < OMTI_DISK_SECTOR_SIZE; i++) {
			logerror(" %02x", data_buffer[i]);
		}

		if (i < data_length) {
			logerror(" ...");
		}
		logerror("\n");
	}
}

/***************************************************************************
 do_command
 ***************************************************************************/

void omti8621_device::do_command(const UINT8 cdb[], const UINT16 cdb_length)
{
	UINT8 lun = get_lun(cdb);
	omti_disk_image_device *disk = our_disks[lun];
	int command_duration = 0; // ms

	log_command( cdb, cdb_length);

	// default to read status and status is successful completion
	omti_state = OMTI_STATE_STATUS;
	status_port |= OMTI_STATUS_IO | OMTI_STATUS_CD;
	command_status = lun ? OMTI_COMMAND_STATUS_LUN : 0;

	if (mask_port & OMTI_MASK_INTE) {
		set_interrupt(CLEAR_LINE);
	}

	if (!disk->m_image->exists()) {
		command_status |= OMTI_COMMAND_STATUS_ERROR; // no such drive
	}

	switch (cdb[0]) {
	case OMTI_CMD_TEST_DRIVE_READY: // 0x00
		if (!disk->m_image->exists())
		{
			set_sense_data(OMTI_SENSE_CODE_DRIVE_NOT_READY, cdb);
		}
		break;

	case OMTI_CMD_RECALIBRATE: // 0x01
		break;

	case OMTI_CMD_REQUEST_SENSE: // 0x03
		set_data_transfer(sense_data, sizeof(sense_data));
		break;

	case OMTI_CMD_READ_VERIFY: // 0x05
		check_disk_address(cdb);
		break;

	case OMTI_CMD_FORMAT_TRACK: // 0x06
		format_track(cdb);
		break;

	case OMTI_CMD_FORMAT_BAD_TRACK: // 0x07
		diskaddr_format_bad_track = get_disk_address(cdb);
		break;

	case OMTI_CMD_READ: // 0x08
		if (check_disk_address(cdb)) {
			// read data from controller
			read_sectors_from_disk(get_disk_address(cdb), cdb[4], lun);
			set_data_transfer(&sector_buffer[0],  OMTI_DISK_SECTOR_SIZE*cdb[4]);
		}
		break;

	case OMTI_CMD_WRITE: // 0x0A
		log_data();
		if (check_disk_address(cdb)) {
			write_sectors_to_disk(get_disk_address(cdb), cdb[4], lun);
		}
		break;

	case OMTI_CMD_SEEK: // 0x0B
		check_disk_address(cdb);
		break;

	case OMTI_CMD_READ_SECTOR_BUFFER: // 0x0E
		set_data_transfer(&sector_buffer[0], OMTI_DISK_SECTOR_SIZE*cdb[4]);
		break;

	case OMTI_CMD_WRITE_SECTOR_BUFFER: // 0x0F
		log_data();
		break;

	case OMTI_CMD_COPY: // 0x20
		if (check_disk_address(cdb) && check_disk_address(cdb+4)) {
			// copy sectors
			copy_sectors (get_disk_address(cdb+4), get_disk_address(cdb), cdb[4], lun);
		}
		break;

	case OMTI_CMD_READ_ESDI_DEFECT_LIST: // 0x37
		set_esdi_defect_list(get_lun(cdb), cdb[1] & 0x1f);
		set_data_transfer(disk->m_esdi_defect_list, sizeof(disk->m_esdi_defect_list));
		break;

#if 0   // this command seems unused by Domain/OS, and it's unclear what the intent of the code is (it makes some versions of GCC quite unhappy)
	case OMTI_CMD_ASSIGN_ALTERNATE_TRACK: // 0x11
		log_data();
		alternate_track_address[0] = get_disk_track(cdb);
		alternate_track_address[1] = get_disk_track(alternate_track_buffer-1);
		break;
#endif

	case OMTI_CMD_READ_DATA_TO_BUFFER: // 0x1E
		if (check_disk_address(cdb)) {
			// read data from controller
			read_sectors_from_disk (get_disk_address(cdb), cdb[4], lun);
			// Domain/OS doesn't expect zero access time
			command_duration += 1; // 1 ms is enough, average time would be 30 ms)
		}
		break;

	case OMTI_CMD_WRITE_DATA_FROM_BUFFER: // 0x1F
		log_data();
		if (check_disk_address(cdb)) {
			write_sectors_to_disk(get_disk_address(cdb), cdb[4], lun);
		}
		break;

	case  OMTI_CMD_RAM_DIAGNOSTICS: // 0xE0
		break;

	case OMTI_CMD_CONTROLLER_INT_DIAGNOSTIC: // 0xE4
		break;

	case OMTI_CMD_READ_LONG: // 0xE5
		if (check_disk_address(cdb)) {
			// read data from controller
			read_sectors_from_disk(get_disk_address(cdb), cdb[4], lun);
			set_data_transfer(&sector_buffer[0], OMTI_DISK_SECTOR_SIZE+6);
		}
		break;

	case OMTI_CMD_WRITE_LONG: // 0xE6
		log_data();
		if (check_disk_address(cdb)) {
			UINT32 diskaddr =  get_disk_address(cdb);
			write_sectors_to_disk(diskaddr, cdb[4], lun);
			// this will spoil the ECC code
			diskaddr_ecc_error = diskaddr;
		}
		break;

	case OMTI_CMD_READ_CONFIGURATION: // 0xEC
		set_configuration_data(get_lun(cdb));
		set_data_transfer(disk->m_config_data, sizeof(disk->m_config_data));
		break;

	case OMTI_CMD_INVALID_COMMAND: // 0xFF
		set_sense_data(OMTI_SENSE_CODE_INVALID_COMMAND, cdb);
		command_status |= OMTI_COMMAND_STATUS_ERROR;
		break;

	default:
		LOG(("do_command: UNEXPECTED command %02x",cdb[0]));
		set_sense_data(OMTI_SENSE_CODE_INVALID_COMMAND, cdb);
		command_status |= OMTI_COMMAND_STATUS_ERROR;
		break;
	}

	if (mask_port & OMTI_MASK_INTE) {
//      if (omti_state != OMTI_STATE_STATUS) {
//          LOG(("do_command: UNEXPECTED omti_state %02x",omti_state));
//      }
		status_port |= OMTI_STATUS_IREQ;
		if (command_duration == 0)
		{
			set_interrupt(ASSERT_LINE);
		}
		else
		{
			// FIXME: should delay omti_state and status_port as well
			m_timer->adjust(attotime::from_msec(command_duration), 0);
		}
	}
}

/***************************************************************************
 get_command_length
 ***************************************************************************/

UINT8 omti8621_device::get_command_length(UINT8 command_byte)
{
	return command_byte == OMTI_CMD_COPY ? 10 : 6;
}

/***************************************************************************
 get_data
 ***************************************************************************/

UINT16 omti8621_device::get_data()
{
	UINT16 data = 0xff;
	if (data_index < data_length) {
		data = data_buffer[data_index++];
		data |= data_buffer[data_index++] << 8;
		if (data_index >= data_length) {
			omti_state = OMTI_STATE_STATUS;
			status_port |= OMTI_STATUS_IO | OMTI_STATUS_CD;
			log_data();
		}
	} else {
		LOG(("UNEXPECTED reading OMTI 8621 data (buffer length exceeded)"));
	}
	return data;
}

/***************************************************************************
 set_data
 ***************************************************************************/

void omti8621_device::set_data(UINT16 data)
{
	if (data_index < data_length) {
		data_buffer[data_index++] = data & 0xff;
		data_buffer[data_index++] = data >> 8;
		if (data_index >= data_length) {
			do_command(command_buffer, command_index);
		}
	} else {
		LOG(("UNEXPECTED writing OMTI 8621 data (buffer length exceeded)"));
	}
}

/***************************************************************************
 OMTI8621 Disk Controller-AT Registers
***************************************************************************/

WRITE16_MEMBER(omti8621_device::write)
{
	switch (mem_mask)
	{
		case 0x00ff:
			write8(space, offset*2, data, mem_mask);
			break;

		case 0xff00:
			write8(space, offset*2+1, data>>8, mem_mask>>8);
			break;

		default:
			set_data(data);
			break;
	}
}

WRITE8_MEMBER(omti8621_device::write8)
{
	switch (offset)
	{
	case OMTI_PORT_DATA_OUT: //  0x00
		switch (omti_state) {
		case OMTI_STATE_COMMAND:
			LOG2(("writing OMTI 8621 Command Register at offset %02x = %02x", offset, data));
			if (command_index == 0) {
				command_length = get_command_length(data);
			}

			if (command_index < command_length) {
				command_buffer[command_index++] = data;
			} else {
				LOG(("UNEXPECTED writing OMTI 8621 Data Register at offset %02x = %02x (command length exceeded)", offset, data));
			}

			if (command_index == command_length) {
				switch (command_buffer[0]) {
				case OMTI_CMD_WRITE: // 0x0A
					// TODO: check diskaddr
					// Fall through
				case OMTI_CMD_WRITE_SECTOR_BUFFER: // 0x0F
					set_data_transfer(&sector_buffer[0],
							OMTI_DISK_SECTOR_SIZE * command_buffer[4]);
					status_port &= ~OMTI_STATUS_IO;
					break;

				case OMTI_CMD_ASSIGN_ALTERNATE_TRACK: // 0x11
					set_data_transfer(alternate_track_buffer, sizeof(alternate_track_buffer));
					status_port &= ~OMTI_STATUS_IO;
					break;

				case OMTI_CMD_WRITE_LONG: // 0xE6
					// TODO: check diskaddr
					set_data_transfer(&sector_buffer[0],
							(OMTI_DISK_SECTOR_SIZE +6) * command_buffer[4]);
					status_port &= ~OMTI_STATUS_IO;
					break;

				default:
					do_command(command_buffer, command_index);
					break;
				}
			}
			break;

		case OMTI_STATE_DATA:
			LOG(("UNEXPECTED: writing OMTI 8621 Data Register at offset %02x = %02x", offset, data));
			break;

		default:
			LOG(("UNEXPECTED writing OMTI 8621 Data Register at offset %02x = %02x (omti state = %02x)", offset, data, omti_state));
			break;
		}
		break;

	case OMTI_PORT_RESET: // 0x01
		LOG2(("writing OMTI 8621 Reset Register at offset %02x = %02x", offset, data));
		device_reset();
		break;

	case OMTI_PORT_SELECT: // 0x02
		LOG2(("writing OMTI 8621 Select Register at offset %02x = %02x (omti state = %02x)", offset, data, omti_state));
		omti_state = OMTI_STATE_COMMAND;

		status_port |= OMTI_STATUS_BUSY | OMTI_STATUS_REQ | OMTI_STATUS_CD;
		status_port &= ~OMTI_STATUS_IO;

		command_status = 0;
		command_index = 0;
		break;

	case OMTI_PORT_MASK: // 0x03
		LOG2(("writing OMTI 8621 Mask Register at offset %02x = %02x", offset, data));
		mask_port = data;

		if ((data & OMTI_MASK_INTE) == 0) {
			status_port &= ~OMTI_STATUS_IREQ;
			set_interrupt(CLEAR_LINE);
		}

		if ((data & OMTI_MASK_DMAE) == 0) {
			status_port &= ~OMTI_STATUS_DREQ;
		}
		break;

	default:
		LOG(("UNEXPECTED writing OMTI 8621 Register at offset %02x = %02x", offset, data));
		break;
	}
}

READ16_MEMBER(omti8621_device::read)
{
	switch (mem_mask)
	{
		case 0x00ff:
			return read8(space, offset*2, mem_mask);
		case 0xff00:
			return read8(space, offset*2+1, mem_mask >> 8) << 8;
		default:
			return get_data();
	}
}

READ8_MEMBER(omti8621_device::read8)
{
	UINT8 data = 0xff;
	static UINT8 last_data = 0xff;

	switch (offset) {
	case OMTI_PORT_DATA_IN: // 0x00
		if (status_port & OMTI_STATUS_CD)
		{
			data = command_status;
			switch (omti_state)
			{
			case OMTI_STATE_COMMAND:
				LOG2(("reading OMTI 8621 Data Status Register 1 at offset %02x = %02x (omti state = %02x)", offset, data, omti_state));
				break;
			case OMTI_STATE_STATUS:
				omti_state = OMTI_STATE_IDLE;
				status_port &= ~(OMTI_STATUS_BUSY | OMTI_STATUS_CD  | OMTI_STATUS_IO | OMTI_STATUS_REQ);
				LOG2(("reading OMTI 8621 Data Status Register 2 at offset %02x = %02x", offset, data));
				break;
			default:
				LOG(("UNEXPECTED reading OMTI 8621 Data Status Register 3 at offset %02x = %02x (omti state = %02x)", offset, data, omti_state));
				break;
			}
		}
		else
		{
			LOG(("UNEXPECTED reading OMTI 8621 Data Register 4 at offset %02x = %02x (status bit C/D = 0)", offset, data));
		}
		break;

	case OMTI_PORT_STATUS: // 0x01
		data = status_port;
		// omit excessive logging
		if (data != last_data)
		{
			LOG2(("reading OMTI 8621 Status Register 5 at offset %02x = %02x", offset, data));
//          last_data = data;
		}
		break;

	case OMTI_PORT_CONFIG: // 0x02
		data = config_port;
		LOG2(("reading OMTI 8621 Configuration Register at offset %02x = %02x", offset, data));
		break;

	case OMTI_PORT_MASK: // 0x03
		data = mask_port ;
		// win.dex will update the mask register with read-modify-write
		// LOG2(("reading OMTI 8621 Mask Register at offset %02x = %02x (UNEXPECTED!)", offset, data));
		break;

	default:
		LOG(("UNEXPECTED reading OMTI 8621 Register at offset %02x = %02x", offset, data));
		break;
	}

	return data;
}

void omti8621_device::set_verbose(int on_off)
{
	verbose = on_off == 0 ? 0 : VERBOSE > 1 ? VERBOSE : 1;
}

/***************************************************************************
 get_sector - get sector diskaddr of logical unit lun into data_buffer
 ***************************************************************************/

UINT32 omti8621_device::get_sector(INT32 diskaddr, UINT8 *data_buffer, UINT32 length, UINT8 lun)
{
	omti_disk_image_device *disk = our_disks[lun];

	if (disk->m_image == NULL || !disk->m_image->exists())
	{
		return 0;
	}
	else
	{
//      LOG1(("omti8621_get_sector %x on lun %d", diskaddr, lun));

		// restrict length to size of 1 sector (i.e. 1024 Byte)
		length = length < OMTI_DISK_SECTOR_SIZE ? length  : OMTI_DISK_SECTOR_SIZE;

		disk->m_image->fseek(diskaddr * OMTI_DISK_SECTOR_SIZE, SEEK_SET);
		disk->m_image->fread(data_buffer, length);

		return length;
	}
}


/***************************************************************************
 omti_set_jumper - set OMI jumpers
 ***************************************************************************/

void omti8621_device::set_jumper(UINT16 disk_type)
{
	LOG1(("set_jumper: disk type=%x", disk_type));

	switch (disk_type)
	{
	case OMTI_DISK_TYPE_348_MB: // Maxtor 380 MB (348-MB FA formatted)
		jumper = OMTI_CONFIG_W22 | OMTI_CONFIG_W23;
		break;

	case OMTI_DISK_TYPE_155_MB: // Micropolis 170 MB (155-MB formatted)
	default:
		jumper = OMTI_CONFIG_W20;
		break;
	}
}

// FDC uses the standard IRQ 6 / DMA 2, doesn't appear to be configurable
WRITE_LINE_MEMBER( omti8621_device::fdc_irq_w )
{
	m_isa->irq6_w(state ? ASSERT_LINE : CLEAR_LINE);
}

WRITE_LINE_MEMBER( omti8621_device::fdc_drq_w )
{
	m_isa->drq2_w(state ? ASSERT_LINE : CLEAR_LINE);
}

UINT8 omti8621_device::dack_r(int line)
{
	return m_fdc->dma_r();
}

void omti8621_device::dack_w(int line, UINT8 data)
{
	return m_fdc->dma_w(data);
}

void omti8621_device::eop_w(int state)
{
	m_fdc->tc_w(state == ASSERT_LINE);
}

//##########################################################################

// device type definition
const device_type OMTI_DISK = &device_creator<omti_disk_image_device>;

omti_disk_image_device::omti_disk_image_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
	: device_t(mconfig, OMTI_DISK, "OMTI8621 ESDI disk", tag, owner, clock, "omti_disk_image", __FILE__),
		device_image_interface(mconfig, *this)
{
}

void omti_disk_image_device::device_config_complete()
{
	update_names(OMTI_DISK, "disk", "disk");
};


/***************************************************************************
 omti_disk_config - configure disk parameters
 ***************************************************************************/

void omti_disk_image_device::omti_disk_config(UINT16 disk_type)
{
	LOG1(("omti_disk_config: configuring disk with type %x", disk_type));

	switch (disk_type)
	{
	case OMTI_DISK_TYPE_348_MB: // Maxtor 380 MB (348-MB FA formatted)
		m_cylinders = 1223;
		m_heads = 15;
		m_sectors = 18;
		break;

	case OMTI_DISK_TYPE_155_MB: // Micropolis 170 MB (155-MB formatted)
	default:
		m_cylinders = 1023;
		m_heads = 8;
		m_sectors = 18;
		break;
	}

	m_type = disk_type;
	m_sectorbytes = OMTI_DISK_SECTOR_SIZE;
	m_sector_count = m_cylinders * m_heads * m_sectors;
}

/*-------------------------------------------------
    device start callback
-------------------------------------------------*/

void omti_disk_image_device::device_start()
{
	m_image = this;

	if (m_image->image_core_file() == NULL)
	{
		LOG1(("device_start_omti_disk: no disk"));
	}
	else
	{
		LOG1(("device_start_omti_disk: with disk image %s",m_image->basename() ));
	}

	// default disk type
	omti_disk_config(OMTI_DISK_TYPE_DEFAULT);
}

/*-------------------------------------------------
    device reset callback
-------------------------------------------------*/

void omti_disk_image_device::device_reset()
{
	LOG1(("device_reset_omti_disk"));

	if (exists() && fseek(0, SEEK_END) == 0)
	{
		UINT32 disk_size = (UINT32)(ftell() / OMTI_DISK_SECTOR_SIZE);
		UINT16 disk_type = disk_size >= 300000 ? OMTI_DISK_TYPE_348_MB : OMTI_DISK_TYPE_155_MB;
		if (disk_type != m_type) {
			LOG1(("device_reset_omti_disk: disk size=%d blocks, disk type=%x", disk_size, disk_type ));
			omti_disk_config(disk_type);
		}
	}
}

/*-------------------------------------------------
   disk image create callback
-------------------------------------------------*/

bool omti_disk_image_device::call_create(int format_type, option_resolution *format_options)
{
	LOG(("device_create_omti_disk: creating OMTI Disk with %d blocks", m_sector_count));

	int x;
	unsigned char sectordata[OMTI_DISK_SECTOR_SIZE]; // empty block data


	memset(sectordata, 0x55, sizeof(sectordata));
	for (x = 0; x < m_sector_count; x++)
	{
		if (fwrite(sectordata, OMTI_DISK_SECTOR_SIZE)
				< OMTI_DISK_SECTOR_SIZE)
		{
			return IMAGE_INIT_FAIL;
		}
	}
	return IMAGE_INIT_PASS;
}