1 // license:BSD-3-Clause
2 // copyright-holders:Ryan Holtz
3 /**********************************************************************
4 
5     STmicro ST6-series microcontroller emulation skeleton
6 
7     To Do:
8         - Cycle counts
9         - STOP, WAIT opcodes
10         - Peripherals
11 
12 **********************************************************************/
13 
14 #include "emu.h"
15 #include "st62xx.h"
16 #include "st62xx_dasm.h"
17 
18 DEFINE_DEVICE_TYPE(ST6228,   st6228_device,   "st6228",   "STmicro ST6228")
19 
st6228_device(const machine_config & mconfig,const char * tag,device_t * owner,uint32_t clock)20 st6228_device::st6228_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
21 	: cpu_device(mconfig, ST6228, tag, owner, clock)
22 	, m_pc(0)
23 	, m_mode(MODE_NMI)
24 	, m_prev_mode(MODE_NORMAL)
25 	, m_program_config("program", ENDIANNESS_LITTLE, 8, 12, 0, address_map_constructor(FUNC(st6228_device::st6228_program_map), this))
26 	, m_data_config("data", ENDIANNESS_LITTLE, 8, 8, 0, address_map_constructor(FUNC(st6228_device::st6228_data_map), this))
27 	, m_porta_out(*this)
28 	, m_portb_out(*this)
29 	, m_portc_out(*this)
30 	, m_portd_out(*this)
31 	, m_program(nullptr)
32 	, m_data(nullptr)
33 	, m_rambank(*this, "rambank")
34 	, m_program_rombank(*this, "program_rombank")
35 	, m_data_rombank(*this, "data_rombank")
36 	, m_rom(*this, this->tag())
37 {
38 }
39 
st6228_program_map(address_map & map)40 void st6228_device::st6228_program_map(address_map &map)
41 {
42 	map(0x000, 0x7ff).bankr(m_program_rombank);
43 	map(0x800, 0xfff).rom().region(tag(), 0x800);
44 }
45 
st6228_data_map(address_map & map)46 void st6228_device::st6228_data_map(address_map &map)
47 {
48 	map(0x00, 0x3f).bankrw(m_rambank);
49 	map(0x40, 0x7f).bankr(m_data_rombank);
50 	map(0x80, 0xff).rw(FUNC(st6228_device::regs_r), FUNC(st6228_device::regs_w));
51 }
52 
device_start()53 void st6228_device::device_start()
54 {
55 	m_pc = 0;
56 
57 	m_program = &space(AS_PROGRAM);
58 	m_data = &space(AS_DATA);
59 
60 	// register our state for the debugger
61 	state_add(STATE_GENPC,     "GENPC",    m_pc).noshow();
62 	state_add(STATE_GENPCBASE, "CURPC",    m_pc).noshow();
63 	state_add(STATE_GENFLAGS,  "GENFLAGS", m_flags[0]).callimport().callexport().formatstr("%6s").noshow();
64 	state_add(STATE_FLAGS,     "FLAGS",    m_flags[0]).mask(0x3f);
65 	state_add(STATE_PC,        "PC",       m_pc).mask(0xfff);
66 	state_add(STATE_SP,        "SP",       m_stack_index).mask(0x7);
67 	state_add(STATE_STACK0,    "STACK0",   m_stack[0]).formatstr("%03X");
68 	state_add(STATE_STACK1,    "STACK1",   m_stack[1]).formatstr("%03X");
69 	state_add(STATE_STACK2,    "STACK2",   m_stack[2]).formatstr("%03X");
70 	state_add(STATE_STACK3,    "STACK3",   m_stack[3]).formatstr("%03X");
71 	state_add(STATE_STACK4,    "STACK4",   m_stack[4]).formatstr("%03X");
72 	state_add(STATE_STACK5,    "STACK5",   m_stack[5]).formatstr("%03X");
73 	state_add(STATE_A,         "A",        m_regs[REG_A]);
74 	state_add(STATE_X,         "X",        m_regs[REG_X]);
75 	state_add(STATE_Y,         "Y",        m_regs[REG_Y]);
76 	state_add(STATE_V,         "V",        m_regs[REG_V]);
77 	state_add(STATE_W,         "W",        m_regs[REG_W]);
78 
79 	save_item(NAME(m_regs));
80 	save_item(NAME(m_ram));
81 	save_item(NAME(m_pc));
82 	save_item(NAME(m_mode));
83 	save_item(NAME(m_prev_mode));
84 	save_item(NAME(m_flags));
85 	save_item(NAME(m_stack));
86 	save_item(NAME(m_stack_index));
87 	save_item(NAME(m_icount));
88 	save_item(NAME(m_port_dir));
89 	save_item(NAME(m_port_option));
90 	save_item(NAME(m_port_data));
91 	save_item(NAME(m_port_pullup));
92 	save_item(NAME(m_port_analog));
93 	save_item(NAME(m_port_input));
94 	save_item(NAME(m_port_irq_enable));
95 
96 	// set our instruction counter
97 	set_icountptr(m_icount);
98 
99 	m_rambank->configure_entries(0, 2, m_ram, 0x40);
100 	m_program_rombank->configure_entries(0, 4, m_rom->base(), 0x800);
101 	m_data_rombank->configure_entries(0, 128, m_rom->base(), 0x40);
102 
103 	m_porta_out.resolve_all_safe();
104 	m_portb_out.resolve_all_safe();
105 	m_portc_out.resolve_all_safe();
106 	m_portd_out.resolve_all_safe();
107 }
108 
device_reset()109 void st6228_device::device_reset()
110 {
111 	std::fill(std::begin(m_regs), std::end(m_regs), 0);
112 	std::fill(std::begin(m_ram), std::end(m_ram), 0);
113 	std::fill(std::begin(m_stack), std::end(m_stack), 0);
114 	std::fill(std::begin(m_flags), std::end(m_flags), 0);
115 
116 	std::fill(std::begin(m_port_dir), std::end(m_port_dir), 0);
117 	std::fill(std::begin(m_port_option), std::end(m_port_option), 0);
118 	std::fill(std::begin(m_port_data), std::end(m_port_data), 0);
119 	std::fill(std::begin(m_port_pullup), std::end(m_port_pullup), 0);
120 	std::fill(std::begin(m_port_analog), std::end(m_port_analog), 0);
121 	std::fill(std::begin(m_port_input), std::end(m_port_input), 0);
122 	std::fill(std::begin(m_port_irq_enable), std::end(m_port_irq_enable), 0);
123 
124 	m_pc = m_program->read_word(VEC_RESET);
125 	m_stack_index = 0;
126 	m_mode = MODE_NMI;
127 	m_prev_mode = MODE_NORMAL;
128 
129 	m_rambank->set_entry(0);
130 	m_program_rombank->set_entry(0);
131 	m_data_rombank->set_entry(0);
132 
133 	m_regs[REG_TIMER_COUNT] = 0xff;
134 	m_regs[REG_TIMER_PRESCALE] = 0x7f;
135 	m_regs[REG_WATCHDOG] = 0xfe;
136 	m_regs[REG_AD_CONTROL] = 0x40;
137 }
138 
memory_space_config() const139 device_memory_interface::space_config_vector st6228_device::memory_space_config() const
140 {
141 	return space_config_vector {
142 		std::make_pair(AS_PROGRAM, &m_program_config),
143 		std::make_pair(AS_DATA,    &m_data_config)
144 	};
145 }
146 
state_string_export(const device_state_entry & entry,std::string & str) const147 void st6228_device::state_string_export(const device_state_entry &entry, std::string &str) const
148 {
149 	switch (entry.index())
150 	{
151 		case STATE_GENFLAGS:
152 			str = string_format("%c%c%c%c%c%c",
153 				(m_flags[2] & FLAG_C) ? 'C' : '.',
154 				(m_flags[2] & FLAG_Z) ? 'Z' : '.',
155 				(m_flags[1] & FLAG_C) ? 'C' : '.',
156 				(m_flags[1] & FLAG_Z) ? 'Z' : '.',
157 				(m_flags[0] & FLAG_C) ? 'C' : '.',
158 				(m_flags[0] & FLAG_Z) ? 'Z' : '.');
159 			break;
160 	}
161 }
162 
create_disassembler()163 std::unique_ptr<util::disasm_interface> st6228_device::create_disassembler()
164 {
165 	return std::make_unique<st62xx_disassembler>();
166 }
167 
168 // TODO: interrupts
WRITE_LINE_MEMBER(st6228_device::porta0_w)169 WRITE_LINE_MEMBER(st6228_device::porta0_w) { m_port_input[PORT_A] &= ~(1 << 0); m_port_input[PORT_A] |= (state << 0); }
WRITE_LINE_MEMBER(st6228_device::porta1_w)170 WRITE_LINE_MEMBER(st6228_device::porta1_w) { m_port_input[PORT_A] &= ~(1 << 1); m_port_input[PORT_A] |= (state << 1); }
WRITE_LINE_MEMBER(st6228_device::porta2_w)171 WRITE_LINE_MEMBER(st6228_device::porta2_w) { m_port_input[PORT_A] &= ~(1 << 2); m_port_input[PORT_A] |= (state << 2); }
WRITE_LINE_MEMBER(st6228_device::porta3_w)172 WRITE_LINE_MEMBER(st6228_device::porta3_w) { m_port_input[PORT_A] &= ~(1 << 3); m_port_input[PORT_A] |= (state << 3); }
WRITE_LINE_MEMBER(st6228_device::porta4_w)173 WRITE_LINE_MEMBER(st6228_device::porta4_w) { m_port_input[PORT_A] &= ~(1 << 4); m_port_input[PORT_A] |= (state << 4); }
WRITE_LINE_MEMBER(st6228_device::porta5_w)174 WRITE_LINE_MEMBER(st6228_device::porta5_w) { m_port_input[PORT_A] &= ~(1 << 5); m_port_input[PORT_A] |= (state << 5); }
175 
WRITE_LINE_MEMBER(st6228_device::portb4_w)176 WRITE_LINE_MEMBER(st6228_device::portb4_w) { m_port_input[PORT_B] &= ~(1 << 4); m_port_input[PORT_B] |= (state << 4); }
WRITE_LINE_MEMBER(st6228_device::portb5_w)177 WRITE_LINE_MEMBER(st6228_device::portb5_w) { m_port_input[PORT_B] &= ~(1 << 5); m_port_input[PORT_B] |= (state << 5); }
WRITE_LINE_MEMBER(st6228_device::portb6_w)178 WRITE_LINE_MEMBER(st6228_device::portb6_w) { m_port_input[PORT_B] &= ~(1 << 6); m_port_input[PORT_B] |= (state << 6); }
179 
WRITE_LINE_MEMBER(st6228_device::portc4_w)180 WRITE_LINE_MEMBER(st6228_device::portc4_w) { m_port_input[PORT_C] &= ~(1 << 4); m_port_input[PORT_C] |= (state << 4); }
WRITE_LINE_MEMBER(st6228_device::portc5_w)181 WRITE_LINE_MEMBER(st6228_device::portc5_w) { m_port_input[PORT_C] &= ~(1 << 5); m_port_input[PORT_C] |= (state << 5); }
WRITE_LINE_MEMBER(st6228_device::portc6_w)182 WRITE_LINE_MEMBER(st6228_device::portc6_w) { m_port_input[PORT_C] &= ~(1 << 6); m_port_input[PORT_C] |= (state << 6); }
WRITE_LINE_MEMBER(st6228_device::portc7_w)183 WRITE_LINE_MEMBER(st6228_device::portc7_w) { m_port_input[PORT_C] &= ~(1 << 7); m_port_input[PORT_C] |= (state << 7); }
184 
WRITE_LINE_MEMBER(st6228_device::portd1_w)185 WRITE_LINE_MEMBER(st6228_device::portd1_w) { m_port_input[PORT_D] &= ~(1 << 1); m_port_input[PORT_D] |= (state << 1); }
WRITE_LINE_MEMBER(st6228_device::portd2_w)186 WRITE_LINE_MEMBER(st6228_device::portd2_w) { m_port_input[PORT_D] &= ~(1 << 2); m_port_input[PORT_D] |= (state << 2); }
WRITE_LINE_MEMBER(st6228_device::portd3_w)187 WRITE_LINE_MEMBER(st6228_device::portd3_w) { m_port_input[PORT_D] &= ~(1 << 3); m_port_input[PORT_D] |= (state << 3); }
WRITE_LINE_MEMBER(st6228_device::portd4_w)188 WRITE_LINE_MEMBER(st6228_device::portd4_w) { m_port_input[PORT_D] &= ~(1 << 4); m_port_input[PORT_D] |= (state << 4); }
WRITE_LINE_MEMBER(st6228_device::portd5_w)189 WRITE_LINE_MEMBER(st6228_device::portd5_w) { m_port_input[PORT_D] &= ~(1 << 5); m_port_input[PORT_D] |= (state << 5); }
WRITE_LINE_MEMBER(st6228_device::portd6_w)190 WRITE_LINE_MEMBER(st6228_device::portd6_w) { m_port_input[PORT_D] &= ~(1 << 6); m_port_input[PORT_D] |= (state << 6); }
WRITE_LINE_MEMBER(st6228_device::portd7_w)191 WRITE_LINE_MEMBER(st6228_device::portd7_w) { m_port_input[PORT_D] &= ~(1 << 7); m_port_input[PORT_D] |= (state << 7); }
192 
set_port_output_bit(uint8_t index,uint8_t bit,uint8_t state)193 void st6228_device::set_port_output_bit(uint8_t index, uint8_t bit, uint8_t state)
194 {
195 	switch (index)
196 	{
197 		case PORT_A:
198 			if (bit < 6)
199 				m_porta_out[bit](state);
200 			break;
201 		case PORT_B:
202 			if (bit >= 4 && bit <= 6)
203 				m_portb_out[bit - 4](state);
204 			break;
205 		case PORT_C:
206 			if (bit >= 4)
207 				m_portc_out[bit - 4](state);
208 			break;
209 		case PORT_D:
210 			if (bit >= 1)
211 				m_portd_out[bit - 1](state);
212 			break;
213 	}
214 }
215 
update_port_mode(uint8_t index,uint8_t changed)216 void st6228_device::update_port_mode(uint8_t index, uint8_t changed)
217 {
218 	const uint8_t dir = m_port_dir[index];
219 	const uint8_t option = m_port_option[index];
220 	for (uint8_t bit = 0; bit < 8; bit++)
221 	{
222 		const uint8_t mask = (1 << bit);
223 		if (BIT(changed, bit) && !BIT(dir, bit))
224 		{
225 			if (BIT(m_port_data[index], bit))
226 			{
227 				m_port_irq_enable[index] &= ~mask;
228 				m_port_pullup[index] &= ~mask;
229 
230 				if (BIT(option, bit))
231 					m_port_analog[index] |= mask;
232 				else
233 					m_port_analog[index] &= ~mask;
234 			}
235 			else
236 			{
237 				m_port_pullup[index] |= mask;
238 				m_port_analog[index] &= ~mask;
239 
240 				if (BIT(option, bit))
241 					m_port_irq_enable[index] |= mask;
242 				else
243 					m_port_irq_enable[index] &= ~mask;
244 			}
245 		}
246 		else if (BIT(dir, bit))
247 		{
248 			m_port_pullup[index] &= ~mask;
249 			m_port_analog[index] &= ~mask;
250 			m_port_irq_enable[index] &= ~mask;
251 		}
252 	}
253 }
254 
regs_w(offs_t offset,uint8_t data)255 void st6228_device::regs_w(offs_t offset, uint8_t data)
256 {
257 	offset += 0x80;
258 
259 	if (offset > REG_W && offset < REG_PORTA_DATA)
260 	{
261 		// Data RAM
262 		m_regs[offset] = data;
263 		return;
264 	}
265 
266 	static char PORT_NAMES[4] = { 'A', 'B', 'C', 'D' };
267 
268 	switch (offset)
269 	{
270 		case REG_X:
271 		case REG_Y:
272 		case REG_V:
273 		case REG_W:
274 		case REG_A:
275 			m_regs[offset] = data;
276 			break;
277 
278 		case REG_DATA_ROM_WINDOW:
279 			m_regs[offset] = data;
280 			m_data_rombank->set_entry(data & 0x7f);
281 			break;
282 
283 		case REG_ROM_BANK_SELECT:
284 			m_regs[offset] = data;
285 			m_program_rombank->set_entry(data & 3);
286 			break;
287 
288 		case REG_RAM_BANK_SELECT:
289 			m_regs[offset] = data;
290 			m_rambank->set_entry(data & 1);
291 			break;
292 
293 		case REG_PORTA_DATA:
294 		case REG_PORTB_DATA:
295 		case REG_PORTC_DATA:
296 		case REG_PORTD_DATA:
297 		{
298 			const uint8_t index = offset - REG_PORTA_DATA;
299 			logerror("%s: Port %c data = %02x\n", machine().describe_context(), PORT_NAMES[index], data);
300 			const uint8_t old_data = m_port_data[index];
301 			const uint8_t changed = old_data ^ data;
302 
303 			m_port_data[index] = data;
304 			update_port_mode(index, changed);
305 
306 			if (changed & m_port_dir[index])
307 			{
308 				for (uint8_t bit = 0; bit < 8; bit++)
309 				{
310 					if (BIT(changed, bit))
311 						set_port_output_bit(index, bit, BIT(data, bit));
312 				}
313 			}
314 			break;
315 		}
316 
317 		case REG_PORTA_DIR:
318 		case REG_PORTB_DIR:
319 		case REG_PORTC_DIR:
320 		case REG_PORTD_DIR:
321 		{
322 			const uint8_t index = offset - REG_PORTA_DIR;
323 			logerror("%s: Port %c dir = %02x\n", machine().describe_context(), PORT_NAMES[index], data);
324 			const uint8_t old_dir = m_port_dir[index];
325 			const uint8_t changed = old_dir ^ data;
326 
327 			m_port_dir[index] = data;
328 			update_port_mode(index, changed);
329 
330 			if (changed)
331 			{
332 				for (uint8_t bit = 0; bit < 8; bit++)
333 				{
334 					if (BIT(changed, bit))
335 					{
336 						set_port_output_bit(index, bit, BIT(m_port_data[index], bit));
337 					}
338 				}
339 			}
340 			break;
341 		}
342 
343 		case REG_PORTA_OPTION:
344 		case REG_PORTB_OPTION:
345 		case REG_PORTC_OPTION:
346 		case REG_PORTD_OPTION:
347 		{
348 			const uint8_t index = offset - REG_PORTA_OPTION;
349 			logerror("%s: Port %c option = %02x\n", machine().describe_context(), PORT_NAMES[index], data);
350 
351 			const uint8_t changed = m_port_option[index] ^ data;
352 			m_port_option[index] = data;
353 
354 			update_port_mode(index, changed);
355 			break;
356 		}
357 
358 		case REG_WATCHDOG:
359 			// Do nothing for now
360 			break;
361 
362 		default:
363 			logerror("%s: Unknown register write: %02x = %02x\n", machine().describe_context(), offset, data);
364 			break;
365 	}
366 }
367 
regs_r(offs_t offset)368 uint8_t st6228_device::regs_r(offs_t offset)
369 {
370 	uint8_t ret = 0;
371 	offset += 0x80;
372 
373 	if (offset > REG_W && offset < REG_PORTA_DATA)
374 	{
375 		// Data RAM
376 		return m_regs[offset];
377 	}
378 
379 	static char PORT_NAMES[4] = { 'A', 'B', 'C', 'D' };
380 
381 	switch (offset)
382 	{
383 		case REG_X:
384 		case REG_Y:
385 		case REG_V:
386 		case REG_W:
387 		case REG_A:
388 			ret = m_regs[offset];
389 			break;
390 
391 		case REG_PORTA_DATA:
392 		case REG_PORTB_DATA:
393 		case REG_PORTC_DATA:
394 		case REG_PORTD_DATA:
395 		{
396 			const uint8_t index = offset - REG_PORTA_DATA;
397 			ret = (m_port_data[index] & m_port_dir[index]) |
398 				  (m_port_input[index] & ~m_port_dir[index]) |
399 				  (m_port_pullup[index] & ~m_port_dir[index]);
400 			logerror("%s: Port %c data read (%02x)\n", machine().describe_context(), PORT_NAMES[index], ret);
401 			break;
402 		}
403 
404 		case REG_PORTA_DIR:
405 		case REG_PORTB_DIR:
406 		case REG_PORTC_DIR:
407 		case REG_PORTD_DIR:
408 		{
409 			const uint8_t index = offset - REG_PORTA_DIR;
410 			ret = m_port_dir[index];
411 			logerror("%s: Port %c direction read (%02x)\n", machine().describe_context(), PORT_NAMES[index], ret);
412 			break;
413 		}
414 
415 		case REG_PORTA_OPTION:
416 		case REG_PORTB_OPTION:
417 		case REG_PORTC_OPTION:
418 		case REG_PORTD_OPTION:
419 		{
420 			const uint8_t index = offset - REG_PORTA_OPTION;
421 			ret = m_port_option[index];
422 			logerror("%s: Port %c option read (%02x)\n", machine().describe_context(), PORT_NAMES[index], ret);
423 			break;
424 		}
425 
426 		default:
427 			logerror("%s: Unknown register read: %02x\n", machine().describe_context(), offset);
428 			break;
429 	}
430 	return ret;
431 }
432 
execute_min_cycles() const433 uint32_t st6228_device::execute_min_cycles() const noexcept
434 {
435 	return 2;
436 }
437 
execute_max_cycles() const438 uint32_t st6228_device::execute_max_cycles() const noexcept
439 {
440 	return 5;
441 }
442 
execute_input_lines() const443 uint32_t st6228_device::execute_input_lines() const noexcept
444 {
445 	return 0;
446 }
447 
execute_set_input(int inputnum,int state)448 void st6228_device::execute_set_input(int inputnum, int state)
449 {
450 	logerror("%s: Unimplemented: execute_set_input line %d = %d\n", machine().describe_context(), inputnum, state);
451 }
452 
tick_timers(int cycles)453 void st6228_device::tick_timers(int cycles)
454 {
455 }
456 
unimplemented_opcode(uint8_t op)457 void st6228_device::unimplemented_opcode(uint8_t op)
458 {
459 	fatalerror("ST62xx: unknown opcode (%02x) at %04x\n", op, m_pc);
460 }
461 
execute_run()462 void st6228_device::execute_run()
463 {
464 	while (m_icount > 0)
465 	{
466 		debugger_instruction_hook(m_pc);
467 
468 		uint8_t op = m_program->read_byte(m_pc);
469 
470 		int cycles = 4;
471 
472 		switch (op)
473 		{
474 			case 0x00: case 0x10: case 0x20: case 0x30: case 0x40: case 0x50: case 0x60: case 0x70:
475 			case 0x80:            case 0xa0: case 0xb0: case 0xc0: case 0xd0: case 0xe0: case 0xf0:
476 			case 0x08: case 0x18: case 0x28: case 0x38: case 0x48: case 0x58: case 0x68: case 0x78:
477 			case 0x88:            case 0xa8: case 0xb8: case 0xc8: case 0xd8: case 0xe8: case 0xf8: // JRNZ e
478 			{
479 				const int8_t e = ((int8_t)op) >> 3;
480 				if (!(m_flags[m_mode] & FLAG_Z))
481 					m_pc += e;
482 				break;
483 			}
484 			case 0x01: case 0x11: case 0x21: case 0x31: case 0x41: case 0x51: case 0x61: case 0x71:
485 			case 0x81: case 0x91: case 0xa1: case 0xb1: case 0xc1: case 0xd1: case 0xe1: case 0xf1: // CALL abc
486 			{
487 				const uint8_t ab = m_program->read_byte(m_pc+1);
488 				m_pc += 2;
489 				const uint16_t abc = ((op & 0xf0) >> 4) | (ab << 4);
490 				if (m_stack_index < 6) // FIXME: magic numbers
491 				{
492 					m_stack[m_stack_index] = m_pc;
493 					m_stack_index++;
494 				}
495 				else
496 				{
497 					// Per documentation: "If more calls [than the maximum] are nested, the latest stacked PC
498 					//                     values will be lost. In this case, returns will return to the PC
499 					//                     values stacked first."
500 				}
501 				m_pc = abc-1;
502 				break;
503 			}
504 			case 0x09: case 0x19: case 0x29: case 0x39: case 0x49: case 0x59: case 0x69: case 0x79:
505 			case 0x89: case 0x99: case 0xa9: case 0xb9: case 0xc9: case 0xd9: case 0xe9: case 0xf9: // JP abc
506 			{
507 				const uint8_t ab = m_program->read_byte(m_pc+1);
508 				const uint16_t abc = ((op & 0xf0) >> 4) | (ab << 4);
509 				m_pc = abc-1;
510 				break;
511 			}
512 			case 0x02: case 0x12: case 0x22: case 0x32: case 0x42: case 0x52: case 0x62: case 0x72:
513 			case 0x82: case 0x92: case 0xa2: case 0xb2: case 0xc2: case 0xd2: case 0xe2: case 0xf2:
514 			case 0x0a: case 0x1a: case 0x2a: case 0x3a: case 0x4a: case 0x5a: case 0x6a: case 0x7a:
515 			case 0x8a: case 0x9a: case 0xaa: case 0xba: case 0xca: case 0xda: case 0xea: case 0xfa: // JRNC abc
516 			{
517 				const int8_t e = ((int8_t)op) >> 3;
518 				if (!(m_flags[m_mode] & FLAG_C))
519 					m_pc += e;
520 				break;
521 			}
522 			case 0x03: case 0x23: case 0x43: case 0x63: case 0x83: case 0xa3: case 0xc3: case 0xe3: // JRR b,rr,ee
523 			{
524 				const uint8_t b = (op >> 5) & 7;
525 				const uint8_t rr = m_program->read_byte(m_pc+1);
526 				const int8_t ee = (int8_t)m_program->read_byte(m_pc+2);
527 				const uint8_t value = m_data->read_byte(rr);
528 				m_pc += 2;
529 				if (!BIT(value, b))
530 					m_pc += ee;
531 				break;
532 			}
533 			case 0x13: case 0x33: case 0x53: case 0x73: case 0x93: case 0xb3: case 0xd3: case 0xf3: // JRS b,rr,ee
534 			{
535 				const uint8_t b = (op >> 5) & 7;
536 				const uint8_t rr = m_program->read_byte(m_pc+1);
537 				const int8_t ee = (int8_t)m_program->read_byte(m_pc+2);
538 				const uint8_t value = m_data->read_byte(rr);
539 				m_pc += 2;
540 				if (BIT(value, b))
541 					m_pc += ee;
542 				break;
543 			}
544 			case 0x0b: case 0x2b: case 0x4b: case 0x6b: case 0x8b: case 0xab: case 0xcb: case 0xeb: // RES b,rr
545 			{
546 				const uint8_t b = (op >> 5) & 7;
547 				const uint8_t rr = m_program->read_byte(m_pc+1);
548 				const uint8_t nn = m_data->read_byte(rr);
549 				m_data->write_byte(rr, nn & ~(1 << b));
550 				m_pc++;
551 				break;
552 			}
553 			case 0x1b: case 0x3b: case 0x5b: case 0x7b: case 0x9b: case 0xbb: case 0xdb: case 0xfb: // SET b,rr
554 			{
555 				const uint8_t b = (op >> 5) & 7;
556 				const uint8_t rr = m_program->read_byte(m_pc+1);
557 				const uint8_t nn = m_data->read_byte(rr);
558 				m_data->write_byte(rr, nn | (1 << b));
559 				m_pc++;
560 				break;
561 			}
562 			case 0x04: case 0x14: case 0x24: case 0x34: case 0x44: case 0x54: case 0x64: case 0x74:
563 			case 0x84: case 0x94: case 0xa4: case 0xb4: case 0xc4: case 0xd4: case 0xe4: case 0xf4:
564 			case 0x0c: case 0x1c: case 0x2c: case 0x3c: case 0x4c: case 0x5c: case 0x6c: case 0x7c:
565 			case 0x8c: case 0x9c: case 0xac: case 0xbc: case 0xcc: case 0xdc: case 0xec: case 0xfc: // JRZ e
566 			{
567 				const int8_t e = ((int8_t)op) >> 3;
568 				if (m_flags[m_mode] & FLAG_Z)
569 					m_pc += e;
570 				break;
571 			}
572 			case 0x06: case 0x16: case 0x26: case 0x36: case 0x46: case 0x56: case 0x66: case 0x76:
573 			case 0x86: case 0x96: case 0xa6: case 0xb6: case 0xc6: case 0xd6: case 0xe6: case 0xf6:
574 			case 0x0e: case 0x1e: case 0x2e: case 0x3e: case 0x4e: case 0x5e: case 0x6e: case 0x7e:
575 			case 0x8e: case 0x9e: case 0xae: case 0xbe: case 0xce: case 0xde: case 0xee: case 0xfe: // JRC e
576 			{
577 				const int8_t e = ((int8_t)op) >> 3;
578 				if (m_flags[m_mode] & FLAG_C)
579 					m_pc += e;
580 				break;
581 			}
582 			case 0x15: // INC X
583 				m_regs[REG_X]++;
584 
585 				if (m_regs[REG_X])
586 					m_flags[m_mode] &= ~FLAG_Z;
587 				else
588 					m_flags[m_mode] |= FLAG_Z;
589 				break;
590 			case 0x35: // LD A,X
591 				m_regs[REG_A] = m_regs[REG_X];
592 
593 				if (m_regs[REG_A])
594 					m_flags[m_mode] &= ~FLAG_Z;
595 				else
596 					m_flags[m_mode] |= FLAG_Z;
597 				break;
598 			case 0x55: // INC Y
599 				m_regs[REG_Y]++;
600 
601 				if (m_regs[REG_Y])
602 					m_flags[m_mode] &= ~FLAG_Z;
603 				else
604 					m_flags[m_mode] |= FLAG_Z;
605 				break;
606 			case 0x75: // LD A,Y
607 				m_regs[REG_A] = m_regs[REG_Y];
608 
609 				if (m_regs[REG_A])
610 					m_flags[m_mode] &= ~FLAG_Z;
611 				else
612 					m_flags[m_mode] |= FLAG_Z;
613 				break;
614 			case 0x95: // INC V
615 				m_regs[REG_V]++;
616 
617 				if (m_regs[REG_V])
618 					m_flags[m_mode] &= ~FLAG_Z;
619 				else
620 					m_flags[m_mode] |= FLAG_Z;
621 				break;
622 			case 0xb5: // LD A,V
623 				m_regs[REG_A] = m_regs[REG_V];
624 
625 				if (m_regs[REG_A])
626 					m_flags[m_mode] &= ~FLAG_Z;
627 				else
628 					m_flags[m_mode] |= FLAG_Z;
629 				break;
630 			case 0xd5: // INC W
631 				m_regs[REG_W]++;
632 
633 				if (m_regs[REG_W])
634 					m_flags[m_mode] &= ~FLAG_Z;
635 				else
636 					m_flags[m_mode] |= FLAG_Z;
637 				break;
638 			case 0xf5: // LD A,W
639 				m_regs[REG_A] = m_regs[REG_W];
640 
641 				if (m_regs[REG_A])
642 					m_flags[m_mode] &= ~FLAG_Z;
643 				else
644 					m_flags[m_mode] |= FLAG_Z;
645 				break;
646 			case 0x0d:  // LDI rr,nn
647 			{
648 				const uint8_t rr = m_program->read_byte(m_pc+1);
649 				const uint8_t nn = m_program->read_byte(m_pc+2);
650 				m_data->write_byte(rr, nn);
651 
652 				if (nn)
653 					m_flags[m_mode] &= ~FLAG_Z;
654 				else
655 					m_flags[m_mode] |= FLAG_Z;
656 				m_pc += 2;
657 				break;
658 			}
659 			case 0x1d: // DEC X
660 				m_regs[REG_X]--;
661 
662 				if (m_regs[REG_X])
663 					m_flags[m_mode] &= ~FLAG_Z;
664 				else
665 					m_flags[m_mode] |= FLAG_Z;
666 				break;
667 			case 0x2d: // COM A
668 				if (BIT(m_regs[REG_A], 7))
669 					m_flags[m_mode] |= FLAG_C;
670 				else
671 					m_flags[m_mode] &= FLAG_C;
672 
673 				m_regs[REG_A] = ~m_regs[REG_A];
674 
675 				if (m_regs[REG_A])
676 					m_flags[m_mode] &= ~FLAG_Z;
677 				else
678 					m_flags[m_mode] |= FLAG_Z;
679 				break;
680 			case 0x3d: // LD X,A
681 				m_regs[REG_X] = m_regs[REG_A];
682 
683 				if (m_regs[REG_X])
684 					m_flags[m_mode] &= ~FLAG_Z;
685 				else
686 					m_flags[m_mode] |= FLAG_Z;
687 				break;
688 			case 0x4d:
689 				if (m_stack_index > 0)
690 				{
691 					m_stack_index--;
692 					m_pc = m_stack[m_stack_index] - 1;
693 					m_mode = m_prev_mode;
694 					m_prev_mode = MODE_NORMAL;
695 				}
696 				else
697 				{
698 					fatalerror("Attempted to RETI with nothing on the stack");
699 				}
700 				break;
701 			case 0x5d: // DEC Y
702 				m_regs[REG_Y]--;
703 
704 				if (m_regs[REG_Y])
705 					m_flags[m_mode] &= ~FLAG_Z;
706 				else
707 					m_flags[m_mode] |= FLAG_Z;
708 				break;
709 			case 0x6d:
710 				//util::stream_format(stream, "STOP");
711 				break;
712 			case 0x7d: // LD Y,A
713 				m_regs[REG_Y] = m_regs[REG_A];
714 
715 				if (m_regs[REG_Y])
716 					m_flags[m_mode] &= ~FLAG_Z;
717 				else
718 					m_flags[m_mode] |= FLAG_Z;
719 				break;
720 			case 0x9d: // DEC V
721 				m_regs[REG_V]--;
722 
723 				if (m_regs[REG_V])
724 					m_flags[m_mode] &= ~FLAG_Z;
725 				else
726 					m_flags[m_mode] |= FLAG_Z;
727 				break;
728 			case 0xad: // RLC
729 			{
730 				const uint8_t old_c = (m_flags[m_mode] & FLAG_C) ? 1 : 0;
731 				if (BIT(m_regs[REG_A], 7))
732 					m_flags[m_mode] |= FLAG_C;
733 				else
734 					m_flags[m_mode] &= ~FLAG_C;
735 				m_regs[REG_A] = (m_regs[REG_A] << 1) | old_c;
736 
737 				if (m_regs[REG_A])
738 					m_flags[m_mode] &= ~FLAG_Z;
739 				else
740 					m_flags[m_mode] |= FLAG_Z;
741 				break;
742 			}
743 			case 0xbd: // LD V,A
744 				m_regs[REG_V] = m_regs[REG_A];
745 
746 				if (m_regs[REG_V])
747 					m_flags[m_mode] &= ~FLAG_Z;
748 				else
749 					m_flags[m_mode] |= FLAG_Z;
750 				break;
751 			case 0xcd:
752 				if (m_stack_index > 0)
753 				{
754 					m_stack_index--;
755 					m_pc = m_stack[m_stack_index] - 1;
756 				}
757 				else
758 				{
759 					fatalerror("Attempted to RET with nothing on the stack");
760 				}
761 				break;
762 			case 0xdd: // DEC W
763 				m_regs[REG_W]--;
764 
765 				if (m_regs[REG_W])
766 					m_flags[m_mode] &= ~FLAG_Z;
767 				else
768 					m_flags[m_mode] |= FLAG_Z;
769 				break;
770 			case 0xed:
771 				//util::stream_format(stream, "WAIT");
772 				break;
773 			case 0xfd: // LD W,A
774 				m_regs[REG_W] = m_regs[REG_A];
775 
776 				if (m_regs[REG_W])
777 					m_flags[m_mode] &= ~FLAG_Z;
778 				else
779 					m_flags[m_mode] |= FLAG_Z;
780 				break;
781 			case 0x07: // LD A,(X)
782 				m_regs[REG_A] = m_data->read_byte(m_regs[REG_X]);
783 
784 				if (m_regs[REG_A])
785 					m_flags[m_mode] &= ~FLAG_Z;
786 				else
787 					m_flags[m_mode] |= FLAG_Z;
788 				break;
789 			case 0x17:  // LDI A,rr
790 			{
791 				m_regs[REG_A] = m_program->read_byte(m_pc+1);
792 
793 				if (m_regs[REG_A])
794 					m_flags[m_mode] &= ~FLAG_Z;
795 				else
796 					m_flags[m_mode] |= FLAG_Z;
797 				m_pc++;
798 				break;
799 			}
800 			case 0x27: // CP A,(X)
801 			{
802 				const uint8_t nn = m_data->read_byte(m_regs[REG_X]);
803 
804 				if (m_regs[REG_A] < nn)
805 				{
806 					m_flags[m_mode] |= FLAG_C;
807 					m_flags[m_mode] &= ~FLAG_Z;
808 				}
809 				else
810 				{
811 					m_flags[m_mode] &= ~FLAG_C;
812 					if (m_regs[REG_A] == nn)
813 						m_flags[m_mode] |= FLAG_Z;
814 					else
815 						m_flags[m_mode] &= ~FLAG_Z;
816 				}
817 				break;
818 			}
819 			case 0x37: // CPI A,nn
820 			{
821 				const uint8_t nn = m_program->read_byte(m_pc+1);
822 
823 				if (m_regs[REG_A] < nn)
824 				{
825 					m_flags[m_mode] |= FLAG_C;
826 					m_flags[m_mode] &= ~FLAG_Z;
827 				}
828 				else
829 				{
830 					m_flags[m_mode] &= ~FLAG_C;
831 					if (m_regs[REG_A] == nn)
832 						m_flags[m_mode] |= FLAG_Z;
833 					else
834 						m_flags[m_mode] &= ~FLAG_Z;
835 				}
836 				m_pc++;
837 				break;
838 			}
839 			case 0x47: // ADD A,(X)
840 			{
841 				const uint8_t nn = m_data->read_byte(m_regs[REG_X]);
842 				const uint16_t sum = m_regs[REG_A] + nn;
843 
844 				if (sum > 0xff)
845 				{
846 					m_flags[m_mode] |= FLAG_C;
847 					m_flags[m_mode] &= ~FLAG_Z;
848 				}
849 				else
850 				{
851 					m_flags[m_mode] &= ~FLAG_C;
852 					if (sum == 0)
853 						m_flags[m_mode] |= FLAG_Z;
854 					else
855 						m_flags[m_mode] &= ~FLAG_Z;
856 				}
857 				m_regs[REG_A] = (uint8_t)sum;
858 				break;
859 			}
860 			case 0x57: // ADDI A,nn
861 			{
862 				const uint8_t nn = m_program->read_byte(m_pc+1);
863 				const uint16_t sum = m_regs[REG_A] + nn;
864 
865 				if (sum > 0xff)
866 				{
867 					m_flags[m_mode] |= FLAG_C;
868 					m_flags[m_mode] &= ~FLAG_Z;
869 				}
870 				else
871 				{
872 					m_flags[m_mode] &= ~FLAG_C;
873 					if (sum == 0)
874 						m_flags[m_mode] |= FLAG_Z;
875 					else
876 						m_flags[m_mode] &= ~FLAG_Z;
877 				}
878 				m_regs[REG_A] = (uint8_t)sum;
879 				m_pc++;
880 				break;
881 			}
882 			case 0x67: // INC (X)
883 			{
884 				const uint8_t rr = m_data->read_byte(m_regs[REG_X]) + 1;
885 				m_data->write_byte(m_regs[REG_X], rr);
886 
887 				if (rr)
888 					m_flags[m_mode] &= ~FLAG_Z;
889 				else
890 					m_flags[m_mode] |= FLAG_Z;
891 				break;
892 			}
893 			case 0x87: // LD (X),A
894 				m_data->write_byte(m_regs[REG_X], m_regs[REG_A]);
895 
896 				if (m_regs[REG_A])
897 					m_flags[m_mode] &= ~FLAG_Z;
898 				else
899 					m_flags[m_mode] |= FLAG_Z;
900 				break;
901 			case 0xa7: // AND A,(X)
902 				m_regs[REG_A] &= m_data->read_byte(m_regs[REG_X]);
903 
904 				if (m_regs[REG_A])
905 					m_flags[m_mode] &= ~FLAG_Z;
906 				else
907 					m_flags[m_mode] |= FLAG_Z;
908 				break;
909 			case 0xb7: // ANDI A,nn
910 			{
911 				m_regs[REG_A] &= m_program->read_byte(m_pc+1);
912 
913 				if (m_regs[REG_A])
914 					m_flags[m_mode] &= ~FLAG_Z;
915 				else
916 					m_flags[m_mode] |= FLAG_Z;
917 				m_pc++;
918 				break;
919 			}
920 			case 0xc7: // SUB A,(X)
921 			{
922 				const uint8_t nn = m_data->read_byte(m_regs[REG_X]);
923 
924 				if (m_regs[REG_A] < nn)
925 				{
926 					m_flags[m_mode] |= FLAG_C;
927 					m_flags[m_mode] &= ~FLAG_Z;
928 				}
929 				else
930 				{
931 					m_flags[m_mode] &= ~FLAG_C;
932 					if (m_regs[REG_A] == nn)
933 						m_flags[m_mode] |= FLAG_Z;
934 					else
935 						m_flags[m_mode] &= ~FLAG_Z;
936 				}
937 				m_regs[REG_A] -= nn;
938 				break;
939 			}
940 			case 0xd7: // SUBI A,nn
941 			{
942 				const uint8_t nn = m_program->read_byte(m_pc+1);
943 
944 				if (m_regs[REG_A] < nn)
945 				{
946 					m_flags[m_mode] |= FLAG_C;
947 					m_flags[m_mode] &= ~FLAG_Z;
948 				}
949 				else
950 				{
951 					m_flags[m_mode] &= ~FLAG_C;
952 					if (m_regs[REG_A] == nn)
953 						m_flags[m_mode] |= FLAG_Z;
954 					else
955 						m_flags[m_mode] &= ~FLAG_Z;
956 				}
957 				m_regs[REG_A] -= nn;
958 				m_pc++;
959 				break;
960 			}
961 			case 0xe7: // DEC (X)
962 			{
963 				const uint8_t rr = m_data->read_byte(m_regs[REG_X]) - 1;
964 				m_data->write_byte(m_regs[REG_X], rr);
965 
966 				if (rr)
967 					m_flags[m_mode] &= ~FLAG_Z;
968 				else
969 					m_flags[m_mode] |= FLAG_Z;
970 				break;
971 			}
972 			case 0x0f: // LD A,(Y)
973 				m_regs[REG_A] = m_data->read_byte(m_regs[REG_Y]);
974 
975 				if (m_regs[REG_A])
976 					m_flags[m_mode] &= ~FLAG_Z;
977 				else
978 					m_flags[m_mode] |= FLAG_Z;
979 				break;
980 			case 0x1f: // LD A,rr
981 			{
982 				m_regs[REG_A] = m_data->read_byte(m_program->read_byte(m_pc+1));
983 
984 				if (m_regs[REG_V])
985 					m_flags[m_mode] &= ~FLAG_Z;
986 				else
987 					m_flags[m_mode] |= FLAG_Z;
988 				m_pc++;
989 				break;
990 			}
991 			case 0x2f: // CP A,(Y)
992 			{
993 				const uint8_t nn = m_data->read_byte(m_regs[REG_Y]);
994 
995 				if (m_regs[REG_A] < nn)
996 				{
997 					m_flags[m_mode] |= FLAG_C;
998 					m_flags[m_mode] &= ~FLAG_Z;
999 				}
1000 				else
1001 				{
1002 					m_flags[m_mode] &= ~FLAG_C;
1003 					if (m_regs[REG_A] == nn)
1004 						m_flags[m_mode] |= FLAG_Z;
1005 					else
1006 						m_flags[m_mode] &= ~FLAG_Z;
1007 				}
1008 				break;
1009 			}
1010 			case 0x3f: // CP A,rr
1011 			{
1012 				const uint8_t nn = m_data->read_byte(m_program->read_byte(m_pc+1));
1013 
1014 				if (m_regs[REG_A] < nn)
1015 				{
1016 					m_flags[m_mode] |= FLAG_C;
1017 					m_flags[m_mode] &= ~FLAG_Z;
1018 				}
1019 				else
1020 				{
1021 					m_flags[m_mode] &= ~FLAG_C;
1022 					if (m_regs[REG_A] == nn)
1023 						m_flags[m_mode] |= FLAG_Z;
1024 					else
1025 						m_flags[m_mode] &= ~FLAG_Z;
1026 				}
1027 				m_pc++;
1028 				break;
1029 			}
1030 			case 0x4f: // ADD A,(Y)
1031 			{
1032 				const uint8_t nn = m_data->read_byte(m_regs[REG_Y]);
1033 				const uint16_t sum = m_regs[REG_A] + nn;
1034 
1035 				if (sum > 0xff)
1036 				{
1037 					m_flags[m_mode] |= FLAG_C;
1038 					m_flags[m_mode] &= ~FLAG_Z;
1039 				}
1040 				else
1041 				{
1042 					m_flags[m_mode] &= ~FLAG_C;
1043 					if (sum == 0)
1044 						m_flags[m_mode] |= FLAG_Z;
1045 					else
1046 						m_flags[m_mode] &= ~FLAG_Z;
1047 				}
1048 				m_regs[REG_A] = (uint8_t)sum;
1049 				break;
1050 			}
1051 			case 0x5f: // ADD A,rr
1052 			{
1053 				const uint8_t nn = m_data->read_byte(m_program->read_byte(m_pc+1));
1054 				const uint16_t sum = m_regs[REG_A] + nn;
1055 
1056 				if (sum > 0xff)
1057 				{
1058 					m_flags[m_mode] |= FLAG_C;
1059 					m_flags[m_mode] &= ~FLAG_Z;
1060 				}
1061 				else
1062 				{
1063 					m_flags[m_mode] &= ~FLAG_C;
1064 					if (sum == 0)
1065 						m_flags[m_mode] |= FLAG_Z;
1066 					else
1067 						m_flags[m_mode] &= ~FLAG_Z;
1068 				}
1069 				m_regs[REG_A] = (uint8_t)sum;
1070 				m_pc++;
1071 				break;
1072 			}
1073 			case 0x6f: // INC (Y)
1074 			{
1075 				const uint8_t rr = m_data->read_byte(m_regs[REG_Y]) + 1;
1076 				m_data->write_byte(m_regs[REG_Y], rr);
1077 
1078 				if (rr)
1079 					m_flags[m_mode] &= ~FLAG_Z;
1080 				else
1081 					m_flags[m_mode] |= FLAG_Z;
1082 				break;
1083 			}
1084 			case 0x7f: // INC rr
1085 			{
1086 				const uint8_t rr = m_program->read_byte(m_pc+1);
1087 				const uint8_t nn = m_data->read_byte(rr) + 1;
1088 				m_data->write_byte(rr, nn);
1089 
1090 				if (nn)
1091 					m_flags[m_mode] &= ~FLAG_Z;
1092 				else
1093 					m_flags[m_mode] |= FLAG_Z;
1094 				m_pc++;
1095 				break;
1096 			}
1097 			case 0x8f: // LD (Y),A
1098 				m_data->write_byte(m_regs[REG_Y], m_regs[REG_A]);
1099 
1100 				if (m_regs[REG_A])
1101 					m_flags[m_mode] &= ~FLAG_Z;
1102 				else
1103 					m_flags[m_mode] |= FLAG_Z;
1104 				break;
1105 			case 0x9f: // LD rr,A
1106 			{
1107 				m_regs[REG_A] = m_data->read_byte(m_program->read_byte(m_pc+1));
1108 
1109 				if (m_regs[REG_A])
1110 					m_flags[m_mode] &= ~FLAG_Z;
1111 				else
1112 					m_flags[m_mode] |= FLAG_Z;
1113 				m_pc++;
1114 				break;
1115 			}
1116 			case 0xaf: // AND A,(Y)
1117 				m_regs[REG_A] &= m_data->read_byte(m_regs[REG_Y]);
1118 
1119 				if (m_regs[REG_A])
1120 					m_flags[m_mode] &= ~FLAG_Z;
1121 				else
1122 					m_flags[m_mode] |= FLAG_Z;
1123 
1124 				break;
1125 			case 0xbf: // AND A,rr
1126 			{
1127 				m_regs[REG_A] &= m_data->read_byte(m_program->read_byte(m_pc+1));
1128 
1129 				if (m_regs[REG_A])
1130 					m_flags[m_mode] &= ~FLAG_Z;
1131 				else
1132 					m_flags[m_mode] |= FLAG_Z;
1133 				m_pc++;
1134 				break;
1135 			}
1136 			case 0xcf: // SUB A,(Y)
1137 			{
1138 				const uint8_t nn = m_data->read_byte(m_regs[REG_Y]);
1139 
1140 				if (m_regs[REG_A] < nn)
1141 				{
1142 					m_flags[m_mode] |= FLAG_C;
1143 					m_flags[m_mode] &= ~FLAG_Z;
1144 				}
1145 				else
1146 				{
1147 					m_flags[m_mode] &= ~FLAG_C;
1148 					if (m_regs[REG_A] == nn)
1149 						m_flags[m_mode] |= FLAG_Z;
1150 					else
1151 						m_flags[m_mode] &= ~FLAG_Z;
1152 				}
1153 				m_regs[REG_A] -= nn;
1154 				break;
1155 			}
1156 			case 0xdf: // SUB A,rr
1157 			{
1158 				const uint8_t nn = m_data->read_byte(m_program->read_byte(m_pc+1));
1159 
1160 				if (m_regs[REG_A] < nn)
1161 				{
1162 					m_flags[m_mode] |= FLAG_C;
1163 					m_flags[m_mode] &= ~FLAG_Z;
1164 				}
1165 				else
1166 				{
1167 					m_flags[m_mode] &= ~FLAG_C;
1168 					if (m_regs[REG_A] == nn)
1169 						m_flags[m_mode] |= FLAG_Z;
1170 					else
1171 						m_flags[m_mode] &= ~FLAG_Z;
1172 				}
1173 				m_regs[REG_A] -= nn;
1174 				m_pc++;
1175 				break;
1176 			}
1177 			case 0xef: // DEC (Y)
1178 			{
1179 				const uint8_t rr = m_data->read_byte(m_regs[REG_Y]) - 1;
1180 				m_data->write_byte(m_regs[REG_Y], rr);
1181 
1182 				if (rr)
1183 					m_flags[m_mode] &= ~FLAG_Z;
1184 				else
1185 					m_flags[m_mode] |= FLAG_Z;
1186 				break;
1187 			}
1188 			case 0xff: // DEC rr
1189 			{
1190 				const uint8_t rr = m_program->read_byte(m_pc+1);
1191 				const uint8_t value = m_data->read_byte(rr) - 1;
1192 				m_data->write_byte(rr, value);
1193 
1194 				if (value)
1195 					m_flags[m_mode] &= ~FLAG_Z;
1196 				else
1197 					m_flags[m_mode] |= FLAG_Z;
1198 				m_pc++;
1199 				break;
1200 			}
1201 			default:
1202 				logerror("%s: Unsupported opcode: %02x\n", op);
1203 		}
1204 
1205 		m_pc++;
1206 
1207 		tick_timers(cycles);
1208 
1209 		m_icount -= cycles;
1210 	}
1211 }
1212