--- a/blastem.c	Thu May 28 21:09:33 2015 -0700
+++ b/blastem.c	Thu May 28 21:19:55 2015 -0700
@@ -33,8 +33,6 @@
 
 #define MAX_SOUND_CYCLES 100000
 
-uint32_t mclks_per_frame = MCLKS_LINE*LINES_NTSC;
-
 uint16_t cart[CARTRIDGE_WORDS];
 uint16_t ram[RAM_WORDS];
 uint8_t z80_ram[Z80_RAM_BYTES];
@@ -125,26 +123,23 @@
 	return 0;
 }
 
-//TODO: Make these dependent on the video mode
-//#define VINT_CYCLE ((MCLKS_LINE * 225 + (148 + 40) * 4)/MCLKS_PER_68K)
-#define ZVINT_CYCLE ((MCLKS_LINE * 225 + (148 + 40) * 4)/MCLKS_PER_Z80)
-//#define VINT_CYCLE ((MCLKS_LINE * 226)/MCLKS_PER_68K)
-//#define ZVINT_CYCLE ((MCLKS_LINE * 226)/MCLKS_PER_Z80)
-
 void adjust_int_cycle(m68k_context * context, vdp_context * v_context)
 {
+	//static int old_int_cycle = CYCLE_NEVER;
+	genesis_context *gen = context->system;
+	if (context->sync_cycle - context->current_cycle > gen->max_cycles) {
+		context->sync_cycle = context->current_cycle + gen->max_cycles;
+	}
 	context->int_cycle = CYCLE_NEVER;
 	if ((context->status & 0x7) < 6) {
 		uint32_t next_vint = vdp_next_vint(v_context);
 		if (next_vint != CYCLE_NEVER) {
-			next_vint /= MCLKS_PER_68K;
 			context->int_cycle = next_vint;
 			context->int_num = 6;
 		}
 		if ((context->status & 0x7) < 4) {
 			uint32_t next_hint = vdp_next_hint(v_context);
 			if (next_hint != CYCLE_NEVER) {
-				next_hint /= MCLKS_PER_68K;
 				if (next_hint < context->int_cycle) {
 					context->int_cycle = next_hint;
 					context->int_num = 4;
@@ -153,6 +148,10 @@
 			}
 		}
 	}
+	/*if (context->int_cycle != old_int_cycle) {
+		printf("int cycle changed to: %d, level: %d @ %d(%d), frame: %d, vcounter: %d, hslot: %d, mask: %d, hint_counter: %d\n", context->int_cycle, context->int_num, v_context->cycles, context->current_cycle, v_context->frame, v_context->vcounter, v_context->hslot, context->status & 0x7, v_context->hint_counter);
+		old_int_cycle = context->int_cycle;
+	}*/
 
 	context->target_cycle = context->int_cycle < context->sync_cycle ? context->int_cycle : context->sync_cycle;
 	/*printf("Cyc: %d, Trgt: %d, Int Cyc: %d, Int: %d, Mask: %X, V: %d, H: %d, HICount: %d, HReg: %d, Line: %d\n",
@@ -163,12 +162,6 @@
 int break_on_sync = 0;
 int save_state = 0;
 
-uint8_t reset = 1;
-uint8_t need_reset = 0;
-uint8_t busreq = 0;
-uint8_t busack = 0;
-uint32_t busack_cycle = CYCLE_NEVER;
-uint8_t new_busack = 0;
 //#define DO_DEBUG_PRINT
 #ifdef DO_DEBUG_PRINT
 #define dprintf printf
@@ -180,32 +173,22 @@
 
 #define Z80_VINT_DURATION 128
 
+void z80_next_int_pulse(z80_context * z_context)
+{
+		genesis_context * gen = z_context->system;
+	z_context->int_pulse_start = vdp_next_vint_z80(gen->vdp);
+	z_context->int_pulse_end = z_context->int_pulse_start + Z80_VINT_DURATION * MCLKS_PER_Z80;
+			}
+
 void sync_z80(z80_context * z_context, uint32_t mclks)
 {
 #ifndef NO_Z80
-	if (z80_enabled && !reset && !busreq) {
-		genesis_context * gen = z_context->system;
-		z_context->sync_cycle = mclks / MCLKS_PER_Z80;
-		if (z_context->current_cycle < z_context->sync_cycle) {
-			if (need_reset) {
-				z80_reset(z_context);
-				need_reset = 0;
-			}
-			uint32_t vint_cycle = vdp_next_vint_z80(gen->vdp) / MCLKS_PER_Z80;
-			while (z_context->current_cycle < z_context->sync_cycle) {
-				if (z_context->iff1 && z_context->current_cycle < (vint_cycle + Z80_VINT_DURATION)) {
-					z_context->int_cycle = vint_cycle < z_context->int_enable_cycle ? z_context->int_enable_cycle : vint_cycle;
-				}
-				z_context->target_cycle = z_context->sync_cycle < z_context->int_cycle ? z_context->sync_cycle : z_context->int_cycle;
-				dprintf("Running Z80 from cycle %d to cycle %d. Native PC: %p\n", z_context->current_cycle, z_context->sync_cycle, z_context->native_pc);
-				z80_run(z_context);
-				dprintf("Z80 ran to cycle %d\n", z_context->current_cycle);
-			}
-		}
+	if (z80_enabled) {
+		z80_run(z_context, mclks);
 	} else
 #endif
 	{
-		z_context->current_cycle = mclks / MCLKS_PER_Z80;
+		z_context->current_cycle = mclks;
 	}
 }
 
@@ -225,24 +208,24 @@
 	//printf("Target: %d, YM bufferpos: %d, PSG bufferpos: %d\n", target, gen->ym->buffer_pos, gen->psg->buffer_pos * 2);
 }
 
-uint32_t frame=0;
+uint32_t last_frame_num;
 m68k_context * sync_components(m68k_context * context, uint32_t address)
 {
-	//TODO: Handle sync targets smaller than a single frame
 	genesis_context * gen = context->system;
 	vdp_context * v_context = gen->vdp;
 	z80_context * z_context = gen->z80;
-	uint32_t mclks = context->current_cycle * MCLKS_PER_68K;
+	uint32_t mclks = context->current_cycle;
 	sync_z80(z_context, mclks);
-	if (mclks >= mclks_per_frame) {
+	sync_sound(gen, mclks);
+	while (context->current_cycle > mclks) {
+		mclks = context->current_cycle;
+		sync_z80(z_context, mclks);
 		sync_sound(gen, mclks);
-		gen->ym->current_cycle -= mclks_per_frame;
-		gen->psg->cycles -= mclks_per_frame;
-		if (gen->ym->write_cycle != CYCLE_NEVER) {
-			gen->ym->write_cycle = gen->ym->write_cycle >= mclks_per_frame/MCLKS_PER_68K ? gen->ym->write_cycle - mclks_per_frame/MCLKS_PER_68K : 0;
-		}
-		//printf("reached frame end | 68K Cycles: %d, MCLK Cycles: %d\n", context->current_cycle, mclks);
-		vdp_run_context(v_context, mclks_per_frame);
+	}
+	vdp_run_context(v_context, mclks);
+	if (v_context->frame != last_frame_num) {
+		//printf("reached frame end %d | MCLK Cycles: %d, Target: %d, VDP cycles: %d, vcounter: %d, hslot: %d\n", last_frame_num, mclks, gen->frame_end, v_context->cycles, v_context->vcounter, v_context->hslot);
+		last_frame_num = v_context->frame;
 
 		if (!headless) {
 			break_on_sync |= wait_render_frame(v_context, frame_limit);
@@ -252,51 +235,47 @@
 				exit(0);
 			}
 		}
-		frame++;
-		mclks -= mclks_per_frame;
-		vdp_adjust_cycles(v_context, mclks_per_frame);
-		io_adjust_cycles(gen->ports, context->current_cycle, mclks_per_frame/MCLKS_PER_68K);
-		io_adjust_cycles(gen->ports+1, context->current_cycle, mclks_per_frame/MCLKS_PER_68K);
-		io_adjust_cycles(gen->ports+2, context->current_cycle, mclks_per_frame/MCLKS_PER_68K);
-		if (busack_cycle != CYCLE_NEVER) {
-			if (busack_cycle > mclks_per_frame/MCLKS_PER_68K) {
-				busack_cycle -= mclks_per_frame/MCLKS_PER_68K;
-			} else {
-				busack_cycle = CYCLE_NEVER;
-				busack = new_busack;
-			}
+		
+		vdp_adjust_cycles(v_context, mclks);
+		io_adjust_cycles(gen->ports, context->current_cycle, mclks);
+		io_adjust_cycles(gen->ports+1, context->current_cycle, mclks);
+		io_adjust_cycles(gen->ports+2, context->current_cycle, mclks);
+		context->current_cycle -= mclks;
+		z80_adjust_cycles(z_context, mclks);
+		gen->ym->current_cycle -= mclks;
+		gen->psg->cycles -= mclks;
+		if (gen->ym->write_cycle != CYCLE_NEVER) {
+			gen->ym->write_cycle = gen->ym->write_cycle >= mclks ? gen->ym->write_cycle - mclks : 0;
 		}
-		context->current_cycle -= mclks_per_frame/MCLKS_PER_68K;
-		if (z_context->current_cycle >= mclks_per_frame/MCLKS_PER_Z80) {
-			z_context->current_cycle -= mclks_per_frame/MCLKS_PER_Z80;
-		} else {
-			z_context->current_cycle = 0;
-		}
-		if (mclks) {
-			vdp_run_context(v_context, mclks);
-		}
-	} else {
-		//printf("running VDP for %d cycles\n", mclks - v_context->cycles);
-		vdp_run_context(v_context, mclks);
-		sync_sound(gen, mclks);
 	}
+	gen->frame_end = vdp_cycles_to_frame_end(v_context);
+	context->sync_cycle = gen->frame_end;
+	//printf("Set sync cycle to: %d @ %d, vcounter: %d, hslot: %d\n", context->sync_cycle, context->current_cycle, v_context->vcounter, v_context->hslot);
 	if (context->int_ack) {
+		//printf("acknowledging %d @ %d:%d, vcounter: %d, hslot: %d\n", context->int_ack, context->current_cycle, v_context->cycles, v_context->vcounter, v_context->hslot);
 		vdp_int_ack(v_context, context->int_ack);
 		context->int_ack = 0;
 	}
+	if (!address && (break_on_sync || save_state)) {
+		context->sync_cycle = context->current_cycle + 1;
+	}
 	adjust_int_cycle(context, v_context);
 	if (address) {
 		if (break_on_sync) {
-		break_on_sync = 0;
-		debugger(context, address);
-	}
-		if (save_state) {
+			break_on_sync = 0;
+			debugger(context, address);
+		}
+		if (save_state && (z_context->pc || (!z_context->reset && !z_context->busreq))) {
 			save_state = 0;
+			//advance Z80 core to the start of an instruction
 			while (!z_context->pc)
 			{
-				sync_z80(z_context, z_context->current_cycle * MCLKS_PER_Z80 + MCLKS_PER_Z80);
+				sync_z80(z_context, z_context->current_cycle + MCLKS_PER_Z80);
 			}
 			save_gst(gen, "savestate.gst", address);
+			puts("Saved state to savestate.gst");
+		} else if(save_state) {
+			context->sync_cycle = context->current_cycle + 1;
 		}
 	}
 	return context;
@@ -317,33 +296,30 @@
 		int blocked;
 		uint32_t before_cycle = v_context->cycles;
 		if (vdp_port < 4) {
-			gen->bus_busy = 1;
+			
 			while (vdp_data_port_write(v_context, value) < 0) {
 				while(v_context->flags & FLAG_DMA_RUN) {
-					vdp_run_dma_done(v_context, mclks_per_frame);
-					if (v_context->cycles >= mclks_per_frame) {
-						context->current_cycle = v_context->cycles / MCLKS_PER_68K;
-						if (context->current_cycle * MCLKS_PER_68K < mclks_per_frame) {
-							++context->current_cycle;
-						}
+					vdp_run_dma_done(v_context, gen->frame_end);
+					if (v_context->cycles >= gen->frame_end) {
+						context->current_cycle = v_context->cycles;
+						gen->bus_busy = 1;
 						sync_components(context, 0);
+						gen->bus_busy = 0;
 					}
 				}
-				//context->current_cycle = v_context->cycles / MCLKS_PER_68K;
+				//context->current_cycle = v_context->cycles;
 			}
 		} else if(vdp_port < 8) {
-			gen->bus_busy = 1;
 			blocked = vdp_control_port_write(v_context, value);
 			if (blocked) {
 				while (blocked) {
 					while(v_context->flags & FLAG_DMA_RUN) {
-						vdp_run_dma_done(v_context, mclks_per_frame);
-						if (v_context->cycles >= mclks_per_frame) {
-							context->current_cycle = v_context->cycles / MCLKS_PER_68K;
-							if (context->current_cycle * MCLKS_PER_68K < mclks_per_frame) {
-								++context->current_cycle;
-							}
+						vdp_run_dma_done(v_context, gen->frame_end);
+						if (v_context->cycles >= gen->frame_end) {
+							context->current_cycle = v_context->cycles;
+							gen->bus_busy = 1;
 							sync_components(context, 0);
+							gen->bus_busy = 0;
 						}
 					}
 					if (blocked < 0) {
@@ -353,6 +329,8 @@
 					}
 				}
 			} else {
+				context->sync_cycle = gen->frame_end = vdp_cycles_to_frame_end(v_context);
+				//printf("Set sync cycle to: %d @ %d, vcounter: %d, hslot: %d\n", context->sync_cycle, context->current_cycle, v_context->vcounter, v_context->hslot);
 				adjust_int_cycle(context, v_context);
 			}
 		} else {
@@ -360,21 +338,18 @@
 			exit(1);
 		}
 		if (v_context->cycles != before_cycle) {
-			//printf("68K paused for %d (%d) cycles at cycle %d (%d) for write\n", v_context->cycles / MCLKS_PER_68K - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle);
-			context->current_cycle = v_context->cycles / MCLKS_PER_68K;
+			//printf("68K paused for %d (%d) cycles at cycle %d (%d) for write\n", v_context->cycles - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle);
+			context->current_cycle = v_context->cycles;
+			//Lock the Z80 out of the bus until the VDP access is complete
+			gen->bus_busy = 1;
+			sync_z80(gen->z80, v_context->cycles);
+			gen->bus_busy = 0;
 		}
 	} else if (vdp_port < 0x18) {
-		sync_sound(gen, context->current_cycle * MCLKS_PER_68K);
 		psg_write(gen->psg, value);
 	} else {
 		//TODO: Implement undocumented test register(s)
 	}
-	if (gen->bus_busy)
-	{
-		//Lock the Z80 out of the bus until the VDP access is complete
-		sync_z80(gen->z80, v_context->cycles);
-		gen->bus_busy = 0;
-	}
 	return context;
 }
 
@@ -383,16 +358,18 @@
 	return vdp_port_write(vdp_port, context, vdp_port < 0x10 ? value | value << 8 : ((vdp_port & 1) ? value : 0));
 }
 
-z80_context * z80_vdp_port_write(uint16_t vdp_port, z80_context * context, uint8_t value)
+void * z80_vdp_port_write(uint32_t vdp_port, void * vcontext, uint8_t value)
 {
+	z80_context * context = vcontext;
 	genesis_context * gen = context->system;
+	vdp_port &= 0xFF;
 	if (vdp_port & 0xE0) {
 		printf("machine freeze due to write to Z80 address %X\n", 0x7F00 | vdp_port);
 		exit(1);
 	}
 	if (vdp_port < 0x10) {
 		//These probably won't currently interact well with the 68K accessing the VDP
-		vdp_run_context(gen->vdp, context->current_cycle * MCLKS_PER_Z80);
+		vdp_run_context(gen->vdp, context->current_cycle);
 		if (vdp_port < 4) {
 			vdp_data_port_write(gen->vdp, value << 8 | value);
 		} else if (vdp_port < 8) {
@@ -402,7 +379,7 @@
 			exit(1);
 		}
 	} else if (vdp_port < 0x18) {
-		sync_sound(gen, context->current_cycle * MCLKS_PER_Z80);
+		sync_sound(gen, context->current_cycle);
 		psg_write(gen->psg, value);
 	} else {
 		vdp_test_port_write(gen->vdp, value);
@@ -437,8 +414,13 @@
 		value = vdp_test_port_read(v_context);
 	}
 	if (v_context->cycles != before_cycle) {
-		//printf("68K paused for %d (%d) cycles at cycle %d (%d) for read\n", v_context->cycles / MCLKS_PER_68K - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle);
-		context->current_cycle = v_context->cycles / MCLKS_PER_68K;
+		//printf("68K paused for %d (%d) cycles at cycle %d (%d) for read\n", v_context->cycles - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle);
+		context->current_cycle = v_context->cycles;
+		//Lock the Z80 out of the bus until the VDP access is complete
+		genesis_context *gen = context->system;
+		gen->bus_busy = 1;
+		sync_z80(gen->z80, v_context->cycles);
+		gen->bus_busy = 0;
 	}
 	return value;
 }
@@ -453,22 +435,50 @@
 	}
 }
 
+uint8_t z80_vdp_port_read(uint32_t vdp_port, void * vcontext)
+{
+	z80_context * context = vcontext;
+	if (vdp_port & 0xE0) {
+		printf("machine freeze due to read from Z80 address %X\n", 0x7F00 | vdp_port);
+		exit(1);
+	}
+	genesis_context * gen = context->system;
+	//VDP access goes over the 68K bus like a bank area access
+	//typical delay from bus arbitration
+	context->current_cycle += 3 * MCLKS_PER_Z80;
+	//TODO: add cycle for an access right after a previous one
+	//TODO: Below cycle time is an estimate based on the time between 68K !BG goes low and Z80 !MREQ goes high
+	//      Needs a new logic analyzer capture to get the actual delay on the 68K side
+	gen->m68k->current_cycle += 8 * MCLKS_PER_68K;
+	
+	
+	vdp_port &= 0x1F;
+	uint16_t ret;
+	if (vdp_port < 0x10) {
+		//These probably won't currently interact well with the 68K accessing the VDP
+		vdp_run_context(gen->vdp, context->current_cycle);
+		if (vdp_port < 4) {
+			ret = vdp_data_port_read(gen->vdp);
+		} else if (vdp_port < 8) {
+			ret = vdp_control_port_read(gen->vdp);
+		} else {
+			printf("Illegal write to HV Counter port %X\n", vdp_port);
+			exit(1);
+		}
+	} else {
+		//TODO: Figure out the correct value today
+		ret = 0xFFFF;
+	}
+	return vdp_port & 1 ? ret : ret >> 8;
+}
+
 uint32_t zram_counter = 0;
-#define Z80_ACK_DELAY 3
-#define Z80_BUSY_DELAY 1//TODO: Find the actual value for this
-#define Z80_REQ_BUSY 1
-#define Z80_REQ_ACK 0
-#define Z80_RES_BUSACK reset
 
 m68k_context * io_write(uint32_t location, m68k_context * context, uint8_t value)
 {
 	genesis_context * gen = context->system;
 	if (location < 0x10000) {
-		if (busack_cycle <= context->current_cycle) {
-			busack = new_busack;
-			busack_cycle = CYCLE_NEVER;
-		}
-		if (!(busack || reset)) {
+		if (!z80_enabled || z80_get_busack(gen->z80, context->current_cycle)) {
 			location &= 0x7FFF;
 			if (location < 0x4000) {
 				z80_ram[location & 0x1FFF] = value;
@@ -476,7 +486,7 @@
 				z80_handle_code_write(location & 0x1FFF, gen->z80);
 #endif
 			} else if (location < 0x6000) {
-				sync_sound(gen, context->current_cycle * MCLKS_PER_68K);
+				sync_sound(gen, context->current_cycle);
 				if (location & 1) {
 					ym_data_write(gen->ym, value);
 				} else if(location & 2) {
@@ -522,22 +532,15 @@
 			}
 		} else {
 			if (location == 0x1100) {
-				if (busack_cycle <= context->current_cycle) {
-					busack = new_busack;
-					busack_cycle = CYCLE_NEVER;
-				}
 				if (value & 1) {
 					dputs("bus requesting Z80");
-
-					if(!reset && !busreq) {
-						sync_z80(gen->z80, context->current_cycle * MCLKS_PER_68K + Z80_ACK_DELAY*MCLKS_PER_Z80);
-						busack_cycle = (gen->z80->current_cycle * MCLKS_PER_Z80) / MCLKS_PER_68K;//context->current_cycle + Z80_ACK_DELAY;
-						new_busack = Z80_REQ_ACK;
+					if (z80_enabled) {
+						z80_assert_busreq(gen->z80, context->current_cycle);
+					} else {
+						gen->z80->busack = 1;
 					}
-					busreq = 1;
 				} else {
-					sync_z80(gen->z80, context->current_cycle * MCLKS_PER_68K);
-					if (busreq) {
+					if (gen->z80->busreq) {
 						dputs("releasing z80 bus");
 						#ifdef DO_DEBUG_PRINT
 						char fname[20];
@@ -546,30 +549,27 @@
 						fwrite(z80_ram, 1, sizeof(z80_ram), f);
 						fclose(f);
 						#endif
-						busack_cycle = ((gen->z80->current_cycle + Z80_BUSY_DELAY) * MCLKS_PER_Z80) / MCLKS_PER_68K;
-						new_busack = Z80_REQ_BUSY;
-						busreq = 0;
 					}
-					//busack_cycle = CYCLE_NEVER;
-					//busack = Z80_REQ_BUSY;
-
+					if (z80_enabled) {
+						z80_clear_busreq(gen->z80, context->current_cycle);
+					} else {
+						gen->z80->busack = 0;
+					}
 				}
 			} else if (location == 0x1200) {
-				sync_z80(gen->z80, context->current_cycle * MCLKS_PER_68K);
+				sync_z80(gen->z80, context->current_cycle);
 				if (value & 1) {
-					if (reset && busreq) {
-						new_busack = 0;
-						busack_cycle = ((gen->z80->current_cycle + Z80_ACK_DELAY) * MCLKS_PER_Z80) / MCLKS_PER_68K;//context->current_cycle + Z80_ACK_DELAY;
+					if (z80_enabled) {
+						z80_clear_reset(gen->z80, context->current_cycle);
+					} else {
+						gen->z80->reset = 0;
 					}
-					//TODO: Deal with the scenario in which reset is not asserted long enough
-					if (reset) {
-						need_reset = 1;
-						//TODO: Add necessary delay between release of reset and start of execution
-						gen->z80->current_cycle = (context->current_cycle * MCLKS_PER_68K) / MCLKS_PER_Z80 + 16;
+				} else {
+					if (z80_enabled) {
+						z80_assert_reset(gen->z80, context->current_cycle);
+					} else {
+						gen->z80->reset = 1;
 					}
-					reset = 0;
-				} else {
-					reset = 1;
 				}
 			}
 		}
@@ -597,16 +597,12 @@
 	uint8_t value;
 	genesis_context *gen = context->system;
 	if (location < 0x10000) {
-		if (busack_cycle <= context->current_cycle) {
-			busack = new_busack;
-			busack_cycle = CYCLE_NEVER;
-		}
-		if (!(busack==Z80_REQ_BUSY || reset)) {
+		if (!z80_enabled || z80_get_busack(gen->z80, context->current_cycle)) {
 			location &= 0x7FFF;
 			if (location < 0x4000) {
 				value = z80_ram[location & 0x1FFF];
 			} else if (location < 0x6000) {
-				sync_sound(gen, context->current_cycle * MCLKS_PER_68K);
+				sync_sound(gen, context->current_cycle);
 				value = ym_read_status(gen->ym);
 			} else {
 				value = 0xFF;
@@ -646,14 +642,10 @@
 			}
 		} else {
 			if (location == 0x1100) {
-				if (busack_cycle <= context->current_cycle) {
-					busack = new_busack;
-					busack_cycle = CYCLE_NEVER;
-				}
-				value = Z80_RES_BUSACK || busack;
-				dprintf("Byte read of BUSREQ returned %d @ %d (reset: %d, busack: %d, busack_cycle %d)\n", value, context->current_cycle, reset, busack, busack_cycle);
+				value = z80_enabled ? !z80_get_busack(gen->z80, context->current_cycle) : !gen->z80->busack;
+				dprintf("Byte read of BUSREQ returned %d @ %d (reset: %d)\n", value, context->current_cycle, gen->z80->reset);
 			} else if (location == 0x1200) {
-				value = !reset;
+				value = !gen->z80->reset;
 			} else {
 				value = 0xFF;
 				printf("Byte read of unknown IO location: %X\n", location);
@@ -674,10 +666,11 @@
 	return value;
 }
 
-z80_context * z80_write_ym(uint16_t location, z80_context * context, uint8_t value)
+void * z80_write_ym(uint32_t location, void * vcontext, uint8_t value)
 {
+	z80_context * context = vcontext;
 	genesis_context * gen = context->system;
-	sync_sound(gen, context->current_cycle * MCLKS_PER_Z80);
+	sync_sound(gen, context->current_cycle);
 	if (location & 1) {
 		ym_data_write(gen->ym, value);
 	} else if (location & 2) {
@@ -688,13 +681,83 @@
 	return context;
 }
 
-uint8_t z80_read_ym(uint16_t location, z80_context * context)
+uint8_t z80_read_ym(uint32_t location, void * vcontext)
 {
+	z80_context * context = vcontext;
 	genesis_context * gen = context->system;
-	sync_sound(gen, context->current_cycle * MCLKS_PER_Z80);
+	sync_sound(gen, context->current_cycle);
 	return ym_read_status(gen->ym);
 }
 
+uint8_t z80_read_bank(uint32_t location, void * vcontext)
+{
+	z80_context * context = vcontext;
+	genesis_context *gen = context->system;
+	if (gen->bus_busy) {
+		context->current_cycle = context->sync_cycle;
+	}
+	//typical delay from bus arbitration
+	context->current_cycle += 3 * MCLKS_PER_Z80;
+	//TODO: add cycle for an access right after a previous one
+	//TODO: Below cycle time is an estimate based on the time between 68K !BG goes low and Z80 !MREQ goes high
+	//      Needs a new logic analyzer capture to get the actual delay on the 68K side
+	gen->m68k->current_cycle += 8 * MCLKS_PER_68K;
+
+	location &= 0x7FFF;
+	if (context->mem_pointers[1]) {
+		return context->mem_pointers[1][location ^ 1];
+	}
+	uint32_t address = context->bank_reg << 15 | location;
+	if (address >= 0xC00000 && address < 0xE00000) {
+		return z80_vdp_port_read(location & 0xFF, context);
+	} else {
+		fprintf(stderr, "Unhandled read by Z80 from address %X through banked memory area (%X)\n", address, context->bank_reg << 15);
+	}
+	return 0;
+}
+
+void *z80_write_bank(uint32_t location, void * vcontext, uint8_t value)
+{
+	z80_context * context = vcontext;
+	genesis_context *gen = context->system;
+	if (gen->bus_busy) {
+		context->current_cycle = context->sync_cycle;
+	}
+	//typical delay from bus arbitration
+	context->current_cycle += 3 * MCLKS_PER_Z80;
+	//TODO: add cycle for an access right after a previous one
+	//TODO: Below cycle time is an estimate based on the time between 68K !BG goes low and Z80 !MREQ goes high
+	//      Needs a new logic analyzer capture to get the actual delay on the 68K side
+	gen->m68k->current_cycle += 8 * MCLKS_PER_68K;
+
+	location &= 0x7FFF;
+	uint32_t address = context->bank_reg << 15 | location;
+	if (address >= 0xE00000) {
+		address &= 0xFFFF;
+		((uint8_t *)ram)[address ^ 1] = value;
+	} else if (address >= 0xC00000) {
+		z80_vdp_port_write(location & 0xFF, context, value);
+	} else {
+		fprintf(stderr, "Unhandled write by Z80 to address %X through banked memory area\n", address);
+	}
+	return context;
+}
+
+void *z80_write_bank_reg(uint32_t location, void * vcontext, uint8_t value)
+{
+	z80_context * context = vcontext;
+
+	context->bank_reg = (context->bank_reg >> 1 | value << 8) & 0x1FF;
+	if (context->bank_reg < 0x80) {
+		genesis_context *gen = context->system;
+		context->mem_pointers[1] = get_native_pointer(context->bank_reg << 15, (void **)gen->m68k->mem_pointers, &gen->m68k->options->gen);
+	} else {
+		context->mem_pointers[1] = NULL;
+	}
+
+	return context;
+}
+
 uint16_t read_sram_w(uint32_t address, m68k_context * context)
 {
 	genesis_context * gen = context->system;
@@ -868,9 +931,7 @@
 
 void init_run_cpu(genesis_context * gen, FILE * address_log, char * statefile, uint8_t * debugger)
 {
-	m68k_context context;
 	m68k_options opts;
-	gen->m68k = &context;
 	memmap_chunk memmap[MAX_MAP_CHUNKS];
 	uint32_t num_chunks;
 	void * initial_mapped = NULL;
@@ -963,23 +1024,24 @@
 		}
 		atexit(save_sram);
 	}
-	init_m68k_opts(&opts, memmap, num_chunks);
+	init_m68k_opts(&opts, memmap, num_chunks, MCLKS_PER_68K);
 	opts.address_log = address_log;
-	init_68k_context(&context, opts.gen.native_code_map, &opts);
+	m68k_context *context = init_68k_context(&opts);
+	gen->m68k = context;
 
-	context.video_context = gen->vdp;
-	context.system = gen;
+	context->video_context = gen->vdp;
+	context->system = gen;
 	//cartridge ROM
-	context.mem_pointers[0] = cart;
-	context.target_cycle = context.sync_cycle = mclks_per_frame/MCLKS_PER_68K;
+	context->mem_pointers[0] = cart;
+	context->target_cycle = context->sync_cycle = gen->frame_end > gen->max_cycles ? gen->frame_end : gen->max_cycles;
 	//work RAM
-	context.mem_pointers[1] = ram;
+	context->mem_pointers[1] = ram;
 	//save RAM/map
-	context.mem_pointers[2] = initial_mapped;
-	context.mem_pointers[3] = (uint16_t *)gen->save_ram;
+	context->mem_pointers[2] = initial_mapped;
+	context->mem_pointers[3] = (uint16_t *)gen->save_ram;
 	uint32_t address;
 	address = cart[2] << 16 | cart[3];
-	translate_m68k_stream(address, &context);
+	translate_m68k_stream(address, context);
 	if (statefile) {
 		uint32_t pc = load_gst(gen, statefile);
 		if (!pc) {
@@ -988,18 +1050,15 @@
 		}
 		printf("Loaded %s\n", statefile);
 		if (debugger) {
-			insert_breakpoint(&context, pc, debugger);
+			insert_breakpoint(context, pc, debugger);
 		}
 		adjust_int_cycle(gen->m68k, gen->vdp);
-#ifndef NO_Z80
-		gen->z80->native_pc =  z80_get_native_address_trans(gen->z80, gen->z80->pc);
-#endif
-		start_68k_context(&context, pc);
+		start_68k_context(context, pc);
 	} else {
 		if (debugger) {
-			insert_breakpoint(&context, address, debugger);
+			insert_breakpoint(context, address, debugger);
 		}
-		m68k_reset(&context);
+		m68k_reset(context);
 	}
 }
 
@@ -1072,6 +1131,15 @@
 		}
 	}
 }
+#ifndef NO_Z80
+const memmap_chunk z80_map[] = {
+	{ 0x0000, 0x4000,  0x1FFF, 0, MMAP_READ | MMAP_WRITE | MMAP_CODE, z80_ram, NULL, NULL, NULL,              NULL },
+	{ 0x8000, 0x10000, 0x7FFF, 0, 0,                                  NULL,    NULL, NULL, z80_read_bank,     z80_write_bank},
+	{ 0x4000, 0x6000,  0x0003, 0, 0,                                  NULL,    NULL, NULL, z80_read_ym,       z80_write_ym},
+	{ 0x6000, 0x6100,  0xFFFF, 0, 0,                                  NULL,    NULL, NULL, NULL,              z80_write_bank_reg},
+	{ 0x7F00, 0x8000,  0x00FF, 0, 0,                                  NULL,    NULL, NULL, z80_vdp_port_read, z80_vdp_port_write}
+};
+#endif
 
 int main(int argc, char ** argv)
 {
@@ -1081,7 +1149,6 @@
 	}
 	set_exe_str(argv[0]);
 	config = load_config();
-	detect_region();
 	int width = -1;
 	int height = -1;
 	int debug = 0;
@@ -1203,6 +1270,8 @@
 	}
 	if (force_version) {
 		version_reg = force_version;
+	} else {
+		detect_region();
 	}
 	update_title();
 	int def_width = 0;
@@ -1217,18 +1286,20 @@
 	height = height < 240 ? (width/320) * 240 : height;
 	uint32_t fps = 60;
 	if (version_reg & 0x40) {
-		mclks_per_frame = MCLKS_LINE * LINES_PAL;
 		fps = 50;
 	}
 	if (!headless) {
-		render_init(width, height, title, fps, fullscreen, use_gl);
+		render_init(width, height, title, fps, fullscreen);
 	}
 	vdp_context v_context;
 	genesis_context gen;
 	memset(&gen, 0, sizeof(gen));
 	gen.master_clock = gen.normal_clock = fps == 60 ? MCLKS_NTSC : MCLKS_PAL;
 
-	init_vdp_context(&v_context);
+	init_vdp_context(&v_context, version_reg & 0x40);
+	gen.frame_end = vdp_cycles_to_frame_end(&v_context);
+	char * config_cycles = tern_find_ptr(config, "clocksmax_cycles");
+	gen.max_cycles = config_cycles ? atoi(config_cycles) : 10000000;
 
 	ym2612_context y_context;
 	ym_init(&y_context, render_sample_rate(), gen.master_clock, MCLKS_PER_YM, render_audio_buffer(), ym_log ? YM_OPT_WAVE_LOG : 0);
@@ -1237,16 +1308,15 @@
 	psg_init(&p_context, render_sample_rate(), gen.master_clock, MCLKS_PER_PSG, render_audio_buffer());
 
 	z80_context z_context;
-	x86_z80_options z_opts;
 #ifndef NO_Z80
-	init_x86_z80_opts(&z_opts);
+	z80_options z_opts;
+	init_z80_opts(&z_opts, z80_map, 5, MCLKS_PER_Z80);
 	init_z80_context(&z_context, &z_opts);
+	z80_assert_reset(&z_context, 0);
 #endif
 
 	z_context.system = &gen;
 	z_context.mem_pointers[0] = z80_ram;
-	z_context.sync_cycle = z_context.target_cycle = mclks_per_frame/MCLKS_PER_Z80;
-	z_context.int_cycle = CYCLE_NEVER;
 	z_context.mem_pointers[1] = z_context.mem_pointers[2] = (uint8_t *)cart;
 
 	gen.z80 = &z_context;
@@ -1254,6 +1324,7 @@
 	gen.ym = &y_context;
 	gen.psg = &p_context;
 	genesis = &gen;
+	setup_io_devices(config, gen.ports);
 
 	int fname_size = strlen(romfname);
 	sram_filename = malloc(fname_size+6);
@@ -1268,7 +1339,7 @@
 	if (i < 0) {
 		strcpy(sram_filename + fname_size, ".sram");
 	}
-	set_keybindings();
+	set_keybindings(gen.ports);
 
 	init_run_cpu(&gen, address_log, statefile, debuggerfun);
 	return 0;