summaryrefslogtreecommitdiffstatshomepage
path: root/src/mame/drivers/didact.cpp
blob: e5f74d458debbf5eb1a19bba322b4f8e4ad96126 (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
// license:BSD-3-Clause
// copyright-holders:Joakim Larsson Edstrom
/*
 *__________________________________________________________________________________________________________
 * The Didact Esselte 100 CPU board                                                                         |
 *__________________________________________________________________________________________________________|
 *
 *  ___________________________________________________________________________________________________________           _____________________________________________________
 * | The Didact Mp68A CPU board, by Anders Andersson 1979                                                      |         |The Didact Mp68A keypad/display  PB6   +oooo+        |
 * |                  +------+ +-------+     +--+                                                              |         |  by Anders Andersson 1979  +-------+  |cass|        |
 * |                  | 7402 | | 74490 |     |  |      +-------+               +--+                            |         |                    +--+    | 9368  |  +----+    +--+|
 * |       +-------+  +------+ +-------+     |  |      |       |               |  |                            |         |+-------+    2x5082-|B |    +-------+            |  ||
 * |       |       |    2112   2112          |  |      | EXP   |               |  |                            |         || 74132 |       7433|CD| 145  PA0-PA3            |E ||
 * |       | ROM   |    +--+   +--+          +--+      | ANS   |               |P |                            |         |+-------+           |DI| +--+               132  |X ||
 * |       | 7641  |    |  |   |  |                    | ION   |               |I |                            |         |+------+------+     | S| |  |               +--+ |P ||
 * |       |       |    |A |   |B |       +-----+      | BUSES |               |A |                            |         ||      |SHIFT |     | P| |  | PA4-PA6       |  | |A ||
 * |       | 512x8 |    |  |   |  |       |     |      | (2 x) |               |  |                            |         || RES  |(led) |     +--+ |  |               |  | |N ||
 * |       |       |    +--+   +--+       |     |      | FOR   |               |A |                            |         ||      |  *   |          +--+               |  | |S ||
 * |       +-------+    RAMS 4x256x4      |     |      |       |               |  |                            |         |+------+------+------+------+               +--+ |I ||
 * |     ROMS 2x512x8   2112   2112       |     |      | KEY   |               |E |                            |         ||      |      |      |      |                    |O ||
 * |       +-------+    +--+   +--+       |CPU  |      | BOARD | +------+      |X |                            |         || ADR  | RUN  | SST  | REG  |                    |N ||
 * |       |       |    |  |   |  |       |6800 |      |       | |      |      |P |                            |         ||  0   |  4   |  8   |  C   |                    |  ||
 * |       | ROM   |    |A |   |B |       |     |      | AND   | |      |      |A |                            |         |+------+------+------+------+                    |C ||
 * |       | 7641  |    |  |   |  |       |     |      |       | |      |      |N |                            |         ||      |      |      |      |                    |O ||
 * |       |       |    +--+   +--+       |     |      | I/O   | | 6820 |      |S |                            |         || STA  | STO  | BPR  | BPS  |                    |N ||
 * |       | 512x8 |    512 bytes RAM     |     |      | BOARDS| | PIA  |      |I |                            |         ||  1   |  5   |  9   |  D   |                    |N ||
 * |       +-------+                      |     |      |       | |  #1  |      |O |                         +-----+      |+------+------+------+------+           +------+ |E ||
 * |     1024 bytes ROM                   |     |      |       | |      |      |N |                         |     |      ||      |      |      |      |           |      | |C ||
 * |                                      +-----+      |       | |      |      |  |                  PIA A  |    |       || EXF  | EXB  | MOV  | PRM  |           |      | |T ||
 * |        7402  7412                                 |       | |      |      |B |                EXPANSION|    |       ||  2   |  6   |  A   |  E   |           |      | |O ||
 * |        +--+  +--+                                 |       | |      |      |U |                CONNECTOR|    |       |+------+------+------+------+           | 6820 | |R ||
 * |        |  |  |  |                                 |       | |      |      |S |                         |   _|       ||      |      |      |      |           | PIA  | |  ||
 * |        |  |  |  |                                 |       | |      |      |  |                     J4  |  |         || CLR  | REL  | REC  | PLA  |           |  #2  | |  ||
 * |        |  |  |  |                                 |       | +------+      |  |                         |  |_        ||  3   |  7   |  B   |  F   |           |      | |  ||
 * |        +--+  +--+         +--------+              |       |               |  |                         |    |       |+------+------+------+------+           |      | |  ||
 * |                  +-+      | 96LS02 |              |       |               |  |                         |    |       | +-------+ +-------+  +------+          |      | |  ||
 * |       R * * * R  |T|      +--------+              |       |               |  |                         |    |       | | 74148 | | 74148 |  | 7400 |          |      | |  ||
 * |       O  X    A  |R|                              |       |               |  |                         |    |       | +-------+ +-------+  +------+          |      | +--+|
 * |       M * * * M  |M|  Oscillator circuits         +-------+               +--+                         |     |      |                PB3    PB0-PB2          |      |     |
 * |                  |_|                               J1   J2                 J3                          +-----+      |       +---------+                      +------+  J1 |
 * |____________________________________________________________________________________________________________|        |______ |  _|||_  |___________________________________|
 *
 *  _____________________________________________________________________________________________   ___________________________________________________________________________
 * |The Didact Mikrodator 6802 CPU board by Lars Bjorklund 1983                            (  ) |  |The Didact Mikrodator 6802 TB16 board by Lars Bj??rklund 1983               |
 * |                                                                                     +----= |  |             +-|||||||-+                                         ______    |
 * |                                                                                     |    = |  | CA2 Tx      |terminal |                                        |  ()  |   |
 * |                                                                                     |    = |  | PA7 Rx      +---------+               +----------+  C1nF,<=R18k|      |   |
 * |     Photo of CPU board mainly covered by TB16 Keypad/Display board                  +--- = |  | CA1 DTR               +-----------+   |          |   CB2->CB1  |  E   |   |
 * |                                                                                            |  |               PA4-PA6 |           | 1 | BCD      |    +----+   |  X   |   |
 * |                                                                                            |  |               ------->| 74LS145   |   | digit 5  |    |LS  |   |  P   |   |
 * |                                                                                            |  |                       +-----------+   |----------|    | 122|   |  A   |   |
 * |                                                                                     +-----=|  |                                   |   |          |    |    |   |  N   |   |
 * |                                                                          +-------+  |     =|  |------ +--------+                  | 2 | BCD      |    |    |   |  S   |   |
 * |                                                                          |       |  |     =|  | RES*  | SHIFT  |  LED( )          |   | digit 4  |    |    |   |  I   |   |
 * |                                                                          |       |  |     =|  |       |  '*'   |    CA2           v   |----------|    +----+   |  O   |   |
 * |                                                                          | 6821  |  |     =|  |   PA3 |PA7 PA2 | PA1      PA0         |          |        +----|  N   |   |
 * |                                                                          | PIA   |  |     =|  |----|--+-----|--+--|-----+--|---+    3 |          |    PB0-|LS  |      |   |
 * |                                                                          |       |  |     =|  |    v  |     v  |  v     |  v   |      | BCD      |     PB7| 244|  C   |   |
 * |                                                                          |       |  |     =|  | ADR   | RUN    | SST    | CON  | 1    | digit 3  |    --->|    |  O   |   |
 * |                                                                          |       |  |     =|  |  0    |  4     |  8     |  C   |      |----------|        |    |  N   |   |
 * |                                                                          |       |  |     =|  |-------+--------+--------+------+      |          |<-------|    |  N   |   |
 * |                                                                          |       |  |     =|  |       |        |        |      |    4 |          |        +----|  E   |   |
 * |                                                                          |       |  |     =|  | STA   | BPS    | USERV  |      | 2    | BCD      |             |  C   |   |
 * |                                                                          |       |  |     =|  |  1    |  5     |  9     |  D   |      | digit 2  |             |  T   |   |
 * |                                                                          |       |  |     =|  |-------+--------+--------+------+      |----------|             |  O   |   |
 * |                                                                          |       |  |     =|  |       |        |        |      |      |          |             |  R   |   |
 * |                                                                          |       |  |     =|  | EXF   | EXB    | MOV    | LOAD | 3  5 | BCD      |             |      |   |
 * |                                                                          |       |  |     =|  |  2    |  6     |  A     |  E   |      | digit 1  |             |      |   |
 * |                                                                          +-------+  |     =|  |-------+--------+--------+------+      |----------|             |      |   |
 * |                                                                                     |     =|  |       |        |        |      |      |          |             |      |   |
 * |                                                                                     +-----=|  | CLR   |  SP    | USERJ  | FLAG | 4  6 | BCD      |             |      |   |
 * |                                                                                            |  |  3    |  7     |  B     |  F   |      | digit 0  |             |  ()  |   |
 * |                                                                                            |  |-------+--------+--------+------+      +----------+             +------+   |
 * |                                                                                            |  |                                                                           |
 * |                                                                                            |  |                                                                           |
 * |____________________________________________________________________________________________|  |___________________________________________________________________________|
 *
 * History of Didact
 *------------------
 * Didact Laromedelsproduktion was started in Linkoping in Sweden by Anders Andersson, Arne Kullbjer and
 * Lars Bjorklund. They constructed a series of microcomputers for educational purposes such as "Mikrodator 6802",
 * Esselte 100 and the Candela computer for the swedish schools to educate the students in assembly programming
 * and BASIC for electro mechanical applications such as stepper motors, simple process control, buttons
 * and LED:s. Didact designs were marketed by Esselte Studium to the swedish schools. The Candela computer
 * was designed to be the big breakthough and was based on OS9 but lost the battle of the swedish schools to
 * the Compis computer by TeleNova which was based on CP/M initially but later both lost to IBM PC.
 *
 * Misc links about the boards supported by this driver.
 *-----------------------------------------------------
 * http://elektronikforumet.com/forum/viewtopic.php?f=11&t=51424
 * http://kilroy71.fastmail.fm/gallery/Miscellaneous/20120729_019.jpg
 * http://elektronikforumet.com/forum/download/file.php?id=63988&mode=view
 * http://elektronikforumet.com/forum/viewtopic.php?f=2&t=79576&start=150#p1203915
 *
 *  TODO:
 *  Didact designs:    mp68a, md6802, md6802v3, Esselte 100, Candela
 * --------------------------------------------------------------------------
 *  - Add PCB layouts   OK     OK
 *  - Dump ROM:s,       OK     OK
 *  - Keyboard          OK     OK
 *  - Display/CRT       OK     OK
 *  - Clickable Artwork RQ     RQ
 *  - Sound             NA     NA
 *  - Cassette i/f
 *  - Expansion bus
 *  - Expansion overlay
 *
 ****************************************************************************/

#include "emu.h"
#include "cpu/m6800/m6800.h"
#include "machine/6821pia.h" // For all boards
#include "video/dm9368.h"    // For the mp68a
#include "machine/74145.h"   // For the md6802
// Generated artwork includes
#include "mp68a.lh"
#include "md6802.lh"

#define VERBOSE 0

#define LOG(x) do { if (VERBOSE) logerror x; } while (0)
#if VERBOSE >= 2
#define logerror printf
#endif

#ifdef _MSC_VER
#define FUNCNAME __func__
#else
#define FUNCNAME __PRETTY_FUNCTION__
#endif

/* Didact base class */
class didact_state : public driver_device
{
	public:
	didact_state(const machine_config &mconfig, device_type type, const char * tag)
		: driver_device(mconfig, type, tag)
		,m_io_line0(*this, "LINE0")
		,m_io_line1(*this, "LINE1")
		,m_io_line2(*this, "LINE2")
		,m_io_line3(*this, "LINE3")
		,m_io_line4(*this, "LINE4")
		,m_line0(0)
		,m_line1(0)
		,m_line2(0)
		,m_line3(0)
		,m_reset(0)
		,m_shift(0)
		,m_led(0)
		{ }
	required_ioport m_io_line0;
	required_ioport m_io_line1;
	required_ioport m_io_line2;
	required_ioport m_io_line3;
	required_ioport m_io_line4;
	UINT8 m_line0;
	UINT8 m_line1;
	UINT8 m_line2;
	UINT8 m_line3;
	UINT8 m_reset;
	UINT8 m_shift;
	UINT8 m_led;
	TIMER_DEVICE_CALLBACK_MEMBER(scan_artwork);
};

/* Esselte 100 driver class */
class e100_state : public didact_state
{
	public:
	e100_state(const machine_config &mconfig, device_type type, const char * tag)
		: didact_state(mconfig, type, tag),
		m_maincpu(*this, "maincpu"),
		m_pia1(*this, "pia1"),
		m_pia2(*this, "pia2")
		{ }
	required_device<m6802_cpu_device> m_maincpu;
	virtual void machine_reset() override { m_maincpu->reset(); LOG(("--->%s()\n", FUNCNAME)); };
protected:
	required_device<pia6821_device> m_pia1;
	required_device<pia6821_device> m_pia2;
};

/* Mikrodator 6802 driver class */
class md6802_state : public didact_state
{
	public:
	md6802_state(const machine_config &mconfig, device_type type, const char * tag)
		: didact_state(mconfig, type, tag)
		,m_maincpu(*this, "maincpu")
		,m_tb16_74145(*this, "tb16_74145")
		,m_segments(0)
		,m_pia1(*this, "pia1")
		,m_pia2(*this, "pia2")
		{ }
	required_device<m6802_cpu_device> m_maincpu;
	required_device<ttl74145_device> m_tb16_74145;
	UINT8 m_segments;
	DECLARE_READ8_MEMBER( pia2_kbA_r );
	DECLARE_WRITE8_MEMBER( pia2_kbA_w );
	DECLARE_READ8_MEMBER( pia2_kbB_r );
	DECLARE_WRITE8_MEMBER( pia2_kbB_w );
	DECLARE_WRITE_LINE_MEMBER( pia2_ca2_w);

	virtual void machine_reset() override;
	virtual void machine_start() override;
protected:
	required_device<pia6821_device> m_pia1;
	required_device<pia6821_device> m_pia2;
};

/* Keyboard */
READ8_MEMBER( md6802_state::pia2_kbA_r )
{
	UINT8 ls145;
	UINT8 pa = 0xff;

	// Read out the selected column
	ls145 = m_tb16_74145->read() & 0x0f;

	// read out the artwork, line04 is handled by the timer
	m_line0 = m_io_line0->read();
	m_line1 = m_io_line1->read();
	m_line2 = m_io_line2->read();
	m_line3 = m_io_line3->read();

#if VERBOSE > 2
	if ((m_line0 | m_line1 | m_line2 | m_line3) != 0)
		LOG(("%s()-->%02x %02x %02x %02x modified by %02x displaying %02x\n", FUNCNAME, m_line0, m_line1, m_line2, m_line3, m_shift, ls145));
#endif

	// Mask out those rows that has a button pressed
	pa &= ~(((~m_line0 & ls145 ) != 0) ? 1 : 0);
	pa &= ~(((~m_line1 & ls145 ) != 0) ? 2 : 0);
	pa &= ~(((~m_line2 & ls145 ) != 0) ? 4 : 0);
	pa &= ~(((~m_line3 & ls145 ) != 0) ? 8 : 0);

	if (m_shift)
	{
		pa &= 0x7f;   // Clear shift bit if button being pressed (PA7) to ground (internal pullup)
		LOG( ("SHIFT is pressed\n") );
	}

#if VERBOSE > 2
	if ((m_line0 | m_line1 | m_line2 | m_line3) != 0)
		LOG(("%s()-->LINE: 0:%02x 1:%02x 2:%02x 3:%02x SHIFT:%02x LS145:%02x PA:%02x\n", FUNCNAME, m_line0, m_line1, m_line2, m_line3, m_shift, ls145, pa));
#endif

	return pa;
}

/* Pull the cathodes low enabling the correct digit and lit the segments held by port B */
WRITE8_MEMBER( md6802_state::pia2_kbA_w )
{
	UINT8 digit_nbr;

//  LOG(("--->%s(%02x)\n", FUNCNAME, data));

	digit_nbr = (data >> 4) & 0x07;
	m_tb16_74145->write( digit_nbr );
	if (digit_nbr < 6)
	{
		output().set_digit_value( digit_nbr, m_segments);
	}
}

/* PIA 2 Port B is all outputs to drive the display so it is very unlikelly that this function is called */
READ8_MEMBER( md6802_state::pia2_kbB_r )
{
	LOG( ("Warning, trying to read from Port B designated to drive the display, please check why\n") );
	logerror("Warning, trying to read from Port B designated to drive the display, please check why\n");
	return 0;
}

/* Port B is fully used ouputting the segment pattern to the display */
WRITE8_MEMBER( md6802_state::pia2_kbB_w )
{
//  LOG(("--->%s(%02x)\n", FUNCNAME, data));

	/* Store the segment pattern but do not lit up the digit here, done by pulling the correct cathode low on Port A */
	m_segments = BITSWAP8(data, 0, 4, 5, 3, 2, 1, 7, 6);
}

WRITE_LINE_MEMBER( md6802_state::pia2_ca2_w )
{
	LOG(("--->%s(%02x) LED is connected through resisitor to +5v so logical 0 will lit it\n", FUNCNAME, state));
	output().set_led_value(m_led, !state);
	m_shift = !state;
}

void md6802_state::machine_start()
{
	LOG(("--->%s()\n", FUNCNAME));
	save_item(NAME(m_shift));
	save_item(NAME(m_led));
	save_item(NAME(m_reset));
}

void md6802_state::machine_reset()
{
	LOG(("--->%s()\n", FUNCNAME));
	m_led = 1;
	m_maincpu->reset();
}

/* Didact mp68a driver class */

// Just a statement that the real mp68a hardware was designed with 6820 and not 6821
// They are functional equivalents BUT has different electrical characteristics.
#define pia6820_device pia6821_device
#define PIA6820 PIA6821
class mp68a_state : public didact_state
{
	public:
	mp68a_state(const machine_config &mconfig, device_type type, const char * tag)
		: didact_state(mconfig, type, tag)
		,m_maincpu(*this, "maincpu")
		,m_digit0(*this, "digit0")
		,m_digit1(*this, "digit1")
		,m_digit2(*this, "digit2")
		,m_digit3(*this, "digit3")
		,m_digit4(*this, "digit4")
		,m_digit5(*this, "digit5")
		,m_pia1(*this, "pia1")
		,m_pia2(*this, "pia2")
		{ }

	required_device<m6800_cpu_device> m_maincpu;

	// The display segment driver device (there is actually just one, needs rewrite to be correct)
	required_device<dm9368_device> m_digit0;
	required_device<dm9368_device> m_digit1;
	required_device<dm9368_device> m_digit2;
	required_device<dm9368_device> m_digit3;
	required_device<dm9368_device> m_digit4;
	required_device<dm9368_device> m_digit5;

	DECLARE_READ8_MEMBER( pia2_kbA_r );
	DECLARE_WRITE8_MEMBER( pia2_kbA_w );
	DECLARE_READ8_MEMBER( pia2_kbB_r );
	DECLARE_WRITE8_MEMBER( pia2_kbB_w );
	DECLARE_READ_LINE_MEMBER( pia2_cb1_r );

	virtual void machine_reset() override;
	virtual void machine_start() override;
protected:
	required_device<pia6820_device> m_pia1;
	required_device<pia6820_device> m_pia2;
};

READ8_MEMBER( mp68a_state::pia2_kbA_r )
{
	LOG(("--->%s\n", FUNCNAME));

	return 0;
}

WRITE8_MEMBER( mp68a_state::pia2_kbA_w )
{
	UINT8 digit_nbr;

#if VERBOSE > 1
	static UINT8 display[] = {' ',' ',' ',' ',' ',' ',' ',' ','\0'};
	const UINT8 hex[] = {' ','0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
#endif

	/* Display memory is at $702 to $708 in AAAADD format (A=address digit, D=Data digit)
	   but we are using data read from the port. */
	digit_nbr = (data >> 4) & 0x07;

	/* There is actually only one 9368 and a 74145 to drive the cathode of the right digit low */
	/* This can be emulated by prentending there are one 9368 per digit, at least for now      */
	switch (digit_nbr)
	{
	case 0: m_digit0->a_w(data & 0x0f); break;
	case 1: m_digit1->a_w(data & 0x0f); break;
	case 2: m_digit2->a_w(data & 0x0f); break;
	case 3: m_digit3->a_w(data & 0x0f); break;
	case 4: m_digit4->a_w(data & 0x0f); break;
	case 5: m_digit5->a_w(data & 0x0f); break;
	case 7: break; // used as an 'unselect' by the ROM between digit accesses.
	default: logerror("Invalid digit index %d\n", digit_nbr);
	}

#if VERBOSE > 1
	display[(data >> 4) & 0x07] = hex[data & 0x0f];
	LOG(("--->%s(%02x) ==> %s\n", FUNCNAME, data, display));
#endif
}

READ8_MEMBER( mp68a_state::pia2_kbB_r )
{
	UINT8 a012, line, pb;

	LOG(("--->%s %02x %02x %02x %02x %02x => ", FUNCNAME, m_line0, m_line1, m_line2, m_line3, m_shift));

	a012 = 0;
	if ((line = (m_line0 | m_line1)) != 0)
	{
		a012 = 8;
		while (a012 > 0 && !(line & (1 << --a012)));
		a012 += 8;
	}
	if ( a012 == 0 && (line = ((m_line2) | m_line3)) != 0)
	{
		a012 = 8;
		while (a012 > 0 && !(line & (1 << --a012)));
	}

	pb  = a012;       // A0-A2 -> PB0-PB3

	if (m_shift)
	{
		pb |= 0x80;   // Set shift bit (PB7)
		m_shift = 0;  // Reset flip flop
		output().set_led_value(m_led, m_shift);
		LOG( ("SHIFT is released\n") );
	}

	LOG(("%02x\n", pb));

	return pb;
}

WRITE8_MEMBER( mp68a_state::pia2_kbB_w )
{
	LOG(("--->%s(%02x)\n", FUNCNAME, data));
}

READ_LINE_MEMBER( mp68a_state::pia2_cb1_r )
{
	m_line0 = m_io_line0->read();
	m_line1 = m_io_line1->read();
	m_line2 = m_io_line2->read();
	m_line3 = m_io_line3->read();

#if VERBOSE
	if ((m_line0 | m_line1 | m_line2 | m_line3) != 0)
		LOG(("%s()-->%02x %02x %02x %02x\n", FUNCNAME, m_line0, m_line1, m_line2, m_line3));
#endif

	return (m_line0 | m_line1 | m_line2 | m_line3) != 0 ? 0 : 1;
}

void mp68a_state::machine_reset()
{
	LOG(("--->%s()\n", FUNCNAME));
	m_maincpu->reset();
}

void mp68a_state::machine_start()
{
	LOG(("--->%s()\n", FUNCNAME));

	/* register for state saving */
	save_item(NAME(m_shift));
	save_item(NAME(m_led));
	save_item(NAME(m_reset));
}

// This map is derived from info in "TEMAL 100 - teknisk manual Esselte 100"
static ADDRESS_MAP_START( e100_map, AS_PROGRAM, 8, e100_state )
	AM_RANGE(0x0000, 0x1fff) AM_RAM
	AM_RANGE(0xc000, 0xc3ff) AM_RAM AM_SHARE("videoram")
	AM_RANGE(0xc808, 0xc80b) AM_DEVREADWRITE("pia1", pia6821_device, read, write)
	AM_RANGE(0xc810, 0xc813) AM_DEVREADWRITE("pia2", pia6821_device, read, write)
	AM_RANGE(0xd000, 0xffff) AM_ROM AM_REGION("maincpu", 0xd000)
ADDRESS_MAP_END

// This address map is traced from schema
static ADDRESS_MAP_START( md6802_map, AS_PROGRAM, 8, md6802_state )
	AM_RANGE(0x0000, 0x1fff) AM_RAM AM_MIRROR(0x1800)
	AM_RANGE(0xa000, 0xa003) AM_DEVREADWRITE("pia1", pia6821_device, read, write) AM_MIRROR(0x1ffc)
	AM_RANGE(0xc000, 0xc003) AM_DEVREADWRITE("pia2", pia6821_device, read, write) AM_MIRROR(0x1ffc)
	AM_RANGE(0xe000, 0xffff) AM_ROM AM_MIRROR(0x1800) AM_REGION("maincpu", 0xe000)
ADDRESS_MAP_END

// This address map is traced from pcb
static ADDRESS_MAP_START( mp68a_map, AS_PROGRAM, 8, mp68a_state )
	AM_RANGE(0x0000, 0x00ff) AM_RAM AM_MIRROR(0xf000)
	AM_RANGE(0x0500, 0x0503) AM_DEVREADWRITE("pia1", pia6820_device, read, write) AM_MIRROR(0xf0fc)
	AM_RANGE(0x0600, 0x0603) AM_DEVREADWRITE("pia2", pia6820_device, read, write) AM_MIRROR(0xf0fc)
	AM_RANGE(0x0700, 0x07ff) AM_RAM AM_MIRROR(0xf000)
	AM_RANGE(0x0800, 0x0bff) AM_ROM AM_MIRROR(0xf400) AM_REGION("maincpu", 0x0800)
ADDRESS_MAP_END

/* Input ports */
static INPUT_PORTS_START( e100 )
INPUT_PORTS_END

static INPUT_PORTS_START( md6802 )
	PORT_START("LINE0") /* KEY ROW 0 */
	PORT_BIT(0x01, 0x01, IPT_KEYBOARD) PORT_NAME("0") PORT_CODE(KEYCODE_0)  PORT_CHAR('0')
	PORT_BIT(0x02, 0x02, IPT_KEYBOARD) PORT_NAME("1") PORT_CODE(KEYCODE_1)  PORT_CHAR('1')
	PORT_BIT(0x04, 0x04, IPT_KEYBOARD) PORT_NAME("2") PORT_CODE(KEYCODE_2)  PORT_CHAR('2')
	PORT_BIT(0x08, 0x08, IPT_KEYBOARD) PORT_NAME("3") PORT_CODE(KEYCODE_3)  PORT_CHAR('3')
	PORT_BIT(0xf0, 0x00, IPT_UNUSED )

	PORT_START("LINE1") /* KEY ROW 1 */
	PORT_BIT(0x01, 0x01, IPT_KEYBOARD) PORT_NAME("4") PORT_CODE(KEYCODE_4)  PORT_CHAR('4')
	PORT_BIT(0x02, 0x02, IPT_KEYBOARD) PORT_NAME("5") PORT_CODE(KEYCODE_5)  PORT_CHAR('5')
	PORT_BIT(0x04, 0x04, IPT_KEYBOARD) PORT_NAME("6") PORT_CODE(KEYCODE_6)  PORT_CHAR('6')
	PORT_BIT(0x08, 0x08, IPT_KEYBOARD) PORT_NAME("7") PORT_CODE(KEYCODE_7)  PORT_CHAR('7')
	PORT_BIT(0xf0, 0x00, IPT_UNUSED )

	PORT_START("LINE2") /* KEY ROW 2 */
	PORT_BIT(0x01, 0x01, IPT_KEYBOARD) PORT_NAME("8") PORT_CODE(KEYCODE_8)  PORT_CHAR('8')
	PORT_BIT(0x02, 0x02, IPT_KEYBOARD) PORT_NAME("9") PORT_CODE(KEYCODE_9)  PORT_CHAR('9')
	PORT_BIT(0x04, 0x04, IPT_KEYBOARD) PORT_NAME("A") PORT_CODE(KEYCODE_A)  PORT_CHAR('A')
	PORT_BIT(0x08, 0x08, IPT_KEYBOARD) PORT_NAME("B") PORT_CODE(KEYCODE_B)  PORT_CHAR('B')
	PORT_BIT(0xf0, 0x00, IPT_UNUSED )

	PORT_START("LINE3") /* KEY ROW 3 */
	PORT_BIT(0x01, 0x01, IPT_KEYBOARD) PORT_NAME("C") PORT_CODE(KEYCODE_C)  PORT_CHAR('C')
	PORT_BIT(0x02, 0x02, IPT_KEYBOARD) PORT_NAME("D") PORT_CODE(KEYCODE_D)  PORT_CHAR('D')
	PORT_BIT(0x04, 0x04, IPT_KEYBOARD) PORT_NAME("E") PORT_CODE(KEYCODE_E)  PORT_CHAR('E')
	PORT_BIT(0x08, 0x08, IPT_KEYBOARD) PORT_NAME("F") PORT_CODE(KEYCODE_F)  PORT_CHAR('F')
	PORT_BIT(0xf0, 0x00, IPT_UNUSED )

	PORT_START("LINE4") /* Special KEY ROW for reset and Shift/'*' keys */
	PORT_BIT(0x08, 0x00, IPT_KEYBOARD) PORT_NAME("*") PORT_CODE(KEYCODE_LSHIFT) PORT_CODE(KEYCODE_RSHIFT) PORT_CHAR('*')
	PORT_BIT(0x04, 0x00, IPT_KEYBOARD) PORT_NAME("Reset") PORT_CODE(KEYCODE_F12)
	PORT_BIT(0xf3, 0x00, IPT_UNUSED )
INPUT_PORTS_END

static INPUT_PORTS_START( mp68a )
	PORT_START("LINE0") /* KEY ROW 0 */
	PORT_BIT(0x10, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("C") PORT_CODE(KEYCODE_C)    PORT_CHAR('C')
	PORT_BIT(0x20, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("D") PORT_CODE(KEYCODE_D)    PORT_CHAR('D')
	PORT_BIT(0x40, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("E") PORT_CODE(KEYCODE_E)    PORT_CHAR('E')
	PORT_BIT(0x80, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("F") PORT_CODE(KEYCODE_F)    PORT_CHAR('F')
	PORT_BIT(0x0f, IP_ACTIVE_HIGH, IPT_UNUSED )

	PORT_START("LINE1") /* KEY ROW 1 */
	PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("8") PORT_CODE(KEYCODE_8)    PORT_CHAR('8')
	PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("9") PORT_CODE(KEYCODE_9)    PORT_CHAR('9')
	PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("A") PORT_CODE(KEYCODE_A)    PORT_CHAR('A')
	PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("B") PORT_CODE(KEYCODE_B)    PORT_CHAR('B')
	PORT_BIT(0xf0, IP_ACTIVE_HIGH, IPT_UNUSED )

	PORT_START("LINE2") /* KEY ROW 2 */
	PORT_BIT(0x10, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("4") PORT_CODE(KEYCODE_4)    PORT_CHAR('4')
	PORT_BIT(0x20, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("5") PORT_CODE(KEYCODE_5)    PORT_CHAR('5')
	PORT_BIT(0x40, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("6") PORT_CODE(KEYCODE_6)    PORT_CHAR('6')
	PORT_BIT(0x80, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("7") PORT_CODE(KEYCODE_7)    PORT_CHAR('7')
	PORT_BIT(0x0f, IP_ACTIVE_HIGH, IPT_UNUSED )

	PORT_START("LINE3") /* KEY ROW 3 */
	PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("0") PORT_CODE(KEYCODE_0)    PORT_CHAR('0')
	PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("1") PORT_CODE(KEYCODE_1)    PORT_CHAR('1')
	PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("2") PORT_CODE(KEYCODE_2)    PORT_CHAR('2')
	PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("3") PORT_CODE(KEYCODE_3)    PORT_CHAR('3')
	PORT_BIT(0xf0, IP_ACTIVE_HIGH, IPT_UNUSED )

	PORT_START("LINE4") /* Special KEY ROW for reset and Shift/'*' keys */
	PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("*") PORT_CODE(KEYCODE_LSHIFT) PORT_CODE(KEYCODE_RSHIFT) PORT_CHAR('*')
	PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("Reset") PORT_CODE(KEYCODE_F12)
	PORT_BIT(0xf3, IP_ACTIVE_HIGH, IPT_UNUSED )
INPUT_PORTS_END

TIMER_DEVICE_CALLBACK_MEMBER(didact_state::scan_artwork)
{
	//  LOG(("--->%s()\n", FUNCNAME));

	// Poll the artwork Reset key
	if ( (m_io_line4->read() & 0x04) )
	{
		LOG( ("RESET is pressed, resetting the CPU\n") );
		m_shift = 0;
		output().set_led_value(m_led, m_shift); // For mp68a only
		if (m_reset == 0)
		{
			machine_reset();
		}
		m_reset = 1; // Inhibit multiple resets
	}

		// Poll the artwork SHIFT/* key
	else if ( (m_io_line4->read() & 0x08) )
	{
		LOG( ("%s", !m_shift ? "SHIFT is set\n" : "") );
		m_shift = 1;
		output().set_led_value(m_led, m_shift); // For mp68a only
	}
	else
	{
		if (m_reset == 1)
		{
			m_reset = 0; // Enable reset again
		}
	}
}

static MACHINE_CONFIG_START( e100, e100_state )
	MCFG_CPU_ADD("maincpu", M6802, XTAL_4MHz)
	MCFG_CPU_PROGRAM_MAP(e100_map)

	/* devices */
	MCFG_DEVICE_ADD("pia1", PIA6821, 0)
	MCFG_DEVICE_ADD("pia2", PIA6821, 0)
MACHINE_CONFIG_END

static MACHINE_CONFIG_START( md6802, md6802_state )
	MCFG_CPU_ADD("maincpu", M6802, XTAL_4MHz)
	MCFG_CPU_PROGRAM_MAP(md6802_map)
	MCFG_DEFAULT_LAYOUT(layout_md6802)

	/* Devices */
	MCFG_DEVICE_ADD("tb16_74145", TTL74145, 0)
	/* PIA #1 0xA000-0xA003 - used differently by laborations and loaded software */
	MCFG_DEVICE_ADD("pia1", PIA6821, 0)

	/* PIA #2 Keyboard & Display 0xC000-0xC003 */
	MCFG_DEVICE_ADD("pia2", PIA6821, 0)
	/* --init----------------------- */
	/* 0xE007 0xC002 (DDR B)     = 0xFF - Port B all outputs and set to 0 (zero) */
	/* 0xE00B 0xC000 (DDR A)     = 0x70 - Port A three outputs and set to 0 (zero) */
	/* 0xE00F 0xC001 (Control A) = 0x3C - */
	/* 0xE013 0xC003 (Control B) = 0x3C - */
	/* --execution-wait for key loop-- */
	/* 0xE026 0xC000             = (Reading Port A)  */
	/* 0xE033 0xC000             = (Reading Port A)  */
	/* 0xE068 0xC000 (Port A)    = 0x60 */
	/* 0xE08A 0xC002 (Port B)    = 0xEE - updating display */
	/* 0xE090 0xC000 (Port A)    = 0x00 - looping in 0x10,0x20,0x30,0x40,0x50 */
	MCFG_PIA_WRITEPA_HANDLER(WRITE8(md6802_state, pia2_kbA_w))
	MCFG_PIA_READPA_HANDLER(READ8(md6802_state, pia2_kbA_r))
	MCFG_PIA_WRITEPB_HANDLER(WRITE8(md6802_state, pia2_kbB_w))
	MCFG_PIA_READPB_HANDLER(READ8(md6802_state, pia2_kbB_r))
	MCFG_PIA_CA2_HANDLER(WRITELINE(md6802_state, pia2_ca2_w))
	MCFG_TIMER_DRIVER_ADD_PERIODIC("artwork_timer", md6802_state, scan_artwork, attotime::from_hz(10))
MACHINE_CONFIG_END

static MACHINE_CONFIG_START( mp68a, mp68a_state )
	// Clock source is based on a N9602N Dual Retriggerable Resettable Monostable Multivibrator oscillator at aprox 505KHz.
	// Trimpot seems broken/stuck at 5K Ohm thu. ROM code 1Ms delay loops suggest 1MHz+
	MCFG_CPU_ADD("maincpu", M6800, 505000)
	MCFG_CPU_PROGRAM_MAP(mp68a_map)
	MCFG_DEFAULT_LAYOUT(layout_mp68a)

	/* Devices */
	/* PIA #1 0x500-0x503 - used differently by laborations and loaded software */
	MCFG_DEVICE_ADD("pia1", PIA6820, 0)

	/* PIA #2 Keyboard & Display 0x600-0x603 */
	MCFG_DEVICE_ADD("pia2", PIA6820, 0)
	/* --init----------------------- */
	/* 0x0BAF 0x601 (Control A) = 0x30 - CA2 is low and enable DDRA */
	/* 0x0BB1 0x603 (Control B) = 0x30 - CB2 is low and enable DDRB */
	/* 0x0BB5 0x600 (DDR A)     = 0xFF - Port A all outputs and set to 0 (zero) */
	/* 0x0BB9 0x602 (DDR B)     = 0x50 - Port B two outputs and set to 0 (zero) */
	/* 0x0BBD 0x601 (Control A) = 0x34 - CA2 is low and lock DDRA */
	/* 0x0BBF 0x603 (Control B) = 0x34 - CB2 is low and lock DDRB */
	/* 0x0BC3 0x602 (Port B)    = 0x40 - Turn on display via RBI* on  */
	/* --execution-wait for key loop-- */
	/* 0x086B Update display sequnc, see below                            */
	/* 0x0826 CB1 read          = 0x603 (Control B)  - is a key presssed? */
	MCFG_PIA_WRITEPA_HANDLER(WRITE8(mp68a_state, pia2_kbA_w))
	MCFG_PIA_READPA_HANDLER(READ8(mp68a_state, pia2_kbA_r))
	MCFG_PIA_WRITEPB_HANDLER(WRITE8(mp68a_state, pia2_kbB_w))
	MCFG_PIA_READPB_HANDLER(READ8(mp68a_state, pia2_kbB_r))
	MCFG_PIA_READCB1_HANDLER(READLINE(mp68a_state, pia2_cb1_r))
	MCFG_PIA_IRQA_HANDLER(DEVWRITELINE("maincpu", m6800_cpu_device, irq_line)) /* Not used by ROM. Combined trace to CPU IRQ with IRQB */
	MCFG_PIA_IRQB_HANDLER(DEVWRITELINE("maincpu", m6800_cpu_device, irq_line)) /* Not used by ROM. Combined trace to CPU IRQ with IRQA */

	/* Display - sequence outputting all '0':s at start */
	/* 0x086B 0x600 (Port A)    = 0x00 */
	/* 0x086B 0x600 (Port A)    = 0x70 */
	/* 0x086B 0x600 (Port A)    = 0x10 */
	/* 0x086B 0x600 (Port A)    = 0x70 */
	/* 0x086B 0x600 (Port A)    = 0x20 */
	/* 0x086B 0x600 (Port A)    = 0x70 */
	/* 0x086B 0x600 (Port A)    = 0x30 */
	/* 0x086B 0x600 (Port A)    = 0x70 */
	/* 0x086B 0x600 (Port A)    = 0x40 */
	/* 0x086B 0x600 (Port A)    = 0x70 */
	/* 0x086B 0x600 (Port A)    = 0x50 */
	/* 0x086B 0x600 (Port A)    = 0x70 */
	MCFG_DEVICE_ADD("digit0", DM9368, 0)
	MCFG_OUTPUT_INDEX(0)
	MCFG_DEVICE_ADD("digit1", DM9368, 0)
	MCFG_OUTPUT_INDEX(1)
	MCFG_DEVICE_ADD("digit2", DM9368, 0)
	MCFG_OUTPUT_INDEX(2)
	MCFG_DEVICE_ADD("digit3", DM9368, 0)
	MCFG_OUTPUT_INDEX(3)
	MCFG_DEVICE_ADD("digit4", DM9368, 0)
	MCFG_OUTPUT_INDEX(4)
	MCFG_DEVICE_ADD("digit5", DM9368, 0)
	MCFG_OUTPUT_INDEX(5)

	MCFG_TIMER_DRIVER_ADD_PERIODIC("artwork_timer", mp68a_state, scan_artwork, attotime::from_hz(10))
MACHINE_CONFIG_END

// TODO: Get a ROM set
ROM_START( e100 )
	ROM_REGION(0x10000, "maincpu", 0)
	ROM_LOAD( "e100U201.bin", 0xd000, 0x0800, CRC(0ff53e1f) SHA1(52002ee22c032775dac383d408c44abe9244724f) )
	ROM_LOAD( "e100U202.bin", 0xd800, 0x0800, CRC(0ff53e1f) SHA1(52002ee22c032775dac383d408c44abe9244724f) )
	ROM_LOAD( "e100U203.bin", 0xe000, 0x0800, CRC(0ff53e1f) SHA1(52002ee22c032775dac383d408c44abe9244724f) )
	ROM_LOAD( "e100U204.bin", 0xe800, 0x0800, CRC(0ff53e1f) SHA1(52002ee22c032775dac383d408c44abe9244724f) )
	ROM_LOAD( "e100U205.bin", 0xf000, 0x0800, CRC(0ff53e1f) SHA1(52002ee22c032775dac383d408c44abe9244724f) )
	ROM_LOAD( "e100U206.bin", 0xf800, 0x0800, CRC(0ff53e1f) SHA1(52002ee22c032775dac383d408c44abe9244724f) )
ROM_END

// TODO split ROM image into proper ROM set
ROM_START( md6802 ) // ROM image from http://elektronikforumet.com/forum/viewtopic.php?f=2&t=79576&start=135#p1203640
	ROM_REGION(0x10000, "maincpu", 0)
	ROM_LOAD( "DIDACT.bin", 0xe000, 0x0800, CRC(50430b1d) SHA1(8e2172a9ae95b04f20aa14177df2463a286c8465) )
ROM_END

ROM_START( mp68a ) // ROM image from http://elektronikforumet.com/forum/viewtopic.php?f=2&t=79576&start=135#p1203640
	ROM_REGION(0x10000, "maincpu", 0)
	ROM_LOAD( "didactA.bin", 0x0800, 0x0200, CRC(aa05e1ce) SHA1(9ce8223efd274045b43ceca3529e037e16e99fdf) )
	ROM_LOAD( "didactB.bin", 0x0a00, 0x0200, CRC(592898dc) SHA1(2962f4817712cae97f3ab37b088fc73e66535ff8) )
ROM_END

//    YEAR  NAME        PARENT      COMPAT  MACHINE     INPUT   CLASS            INIT        COMPANY             FULLNAME           FLAGS
COMP( 1979, mp68a,      0,          0,      mp68a,      mp68a,  driver_device,   0,          "Didact AB",        "mp68a",           MACHINE_NO_SOUND_HW )
COMP( 1982, e100,       0,          0,      e100,       e100,   driver_device,   0,          "Didact AB",        "Esselte 100",     MACHINE_IS_SKELETON )
COMP( 1983, md6802,     0,          0,      md6802,     md6802, driver_device,   0,          "Didact AB",        "Mikrodator 6802", MACHINE_NO_SOUND_HW )