SNK M68000 (Ikari III) FPGA Implementation

FPGA compatible core of SNK M68000 (Ikari III based) arcade hardware for MiSTerFPGA written by Darren Olafson. FPGA implementation has been verified against schematics for Ikari III (A7007). PCB measurements taken from Datsugoku: Prisoners of War (A7008), Street Smart (A8007), and Ikari III: The Rescue (A7007).

Ikari III PCB donated by atrac17 / DJ Hard Rich and verified by Darren Olafson. Other SNK68K PCB verification done by atrac17. The intent is for this core to be a 1:1 playable implementation of SNK M68000 (Ikari III) arcade hardware. Currently in beta state, this core is in active development with assistance from atrac17.

Supported Games

Title	PCB Number	Status	Released	ROM Set
脱獄: Prisoners of War P.O.W.: Prisoners of War	A7008	Implemented	Yes	.245 merged
怒III Ikari III: The Rescue	A7007	Implemented	Yes	.245 merged
Street Smart	A7008 / A8007	Implemented	Yes	.245 merged
SAR: Search and Rescue	A8007	Implemented	Yes	.245 merged

External Modules

Name	Purpose	Author
fx68k	Motorola 68000 CPU	Jorge Cwik
t80	Zilog Z80 CPU	Daniel Wallner
jtopl2	Yamaha OPL 2	Jose Tejada
jt7759	NEC uPD7759	Jose Tejada
yc_out	Y/C Video Module	Mike Simone

Known Issues / Tasks

• GFX toggles for sprite layers [Task - Low Priority]
• Measure full timings from PCB(s) for analog output [Task - Low Priority]
  
  
• Minor screen tearing present in Ikari III, sprites updating midscreen / check int and memory access [Issue]
• Correct colour palette in P.O.W. - Prisoners of War (US Version 1); dependent on sprite location / action [Issue]
• Correct text layer in 脱獄 / P.O.W. - Prisoners of War (US Version 1, Mask ROM Sprites) [Issue]
• Correct missing pixels during scrolling transitions for 脱獄 / P.O.W. - Prisoners of War (US Version 1, Mask ROM Sprites) [Issue]
• Audio issues known, may be an issue with the jtopl2 core or the current usage [Issue]

PCB Check List

FPGA implementation has been verified against schematics schematics for Ikari III. PCB measurements taken from Datsugoku: Prisoners of War (A7008), Street Smart (A8007), and Ikari III: The Resucue (A7007).

Clock Information

H-Sync	V-Sync	Source	PCB Number
15.625kHz	59.185606Hz	DSLogic+	A7008 (P.O.W.)
15.625kHz	59.185606Hz	ADALM2000	A7007 (IK3)
15.625kHz	59.185606Hz	DSLogic+	A8007 (SS)

Crystal Oscillators

Location	PCB Number	Freq (MHz)	Use
X-4 (4MHZ)	A7008 (P.O.W.) / A8007 (SS)	4.000	Z80 / YM3812 / uPD7759
X-2 (18MHZ)	A7008 (P.O.W.) / A8007 (SS)	18.000	M68000
X-1 (24MHz)	A7008 (P.O.W.) / A8007 (SS)	24.000	Video / Pixel Clock

Location	PCB Number	Freq (MHz)	Use
F-18 (4MHZ)	A7007 (IK3) / A8007 (SAR)	4.000	Z80 / YM3812 / uPD7759
H-17 (18MHZ)	A7007 (IK3) / A8007 (SAR)	18.000	M68000
E-9 (24MHz)	A7007 (IK3) / A8007 (SAR)	24.000	Video / Pixel Clock

Pixel clock: 6.00 MHz

Estimated geometry:

383 pixels/line

263 pixels/line

Main Components

Location	PCB Number	Chip	Use
68000	A7008 (P.O.W.) / A8007 (SS)	Motorola 68000 CPU	Main CPU
Z-80A	A7008 (P.O.W.) / A8007 (SS)	Zilog Z80 CPU	Sound CPU
YM3812	A7008 (P.O.W.) / A8007 (SS)	Yamaha YM3812	OPL2
7759	A7008 (P.O.W.) / A8007 (SS)	NEC uPD7759	ADPCM Decoder

Location	PCB Number	Chip	Use
H-11/12	A7007 (IK3) / A8007 (SAR)	Motorola 68000 CPU	Main CPU
Z80	A7007 (IK3) / A8007 (SAR)	Zilog Z80 CPU	Sound CPU
YM3812	A7007 (IK3) / A8007 (SAR)	Yamaha YM3812	OPL2
C-18	A7007 (IK3) / A8007 (SAR)	NEC uPD7759	ADPCM Decoder

Custom Components

Location	PCB Number	Chip	Use
SNKCLK	A7007 (IK3) / A8007 (SAR)	SNK CLK	Counter
SNKI/O	A7007 (IK3) / A8007 (SAR)	SNK I/O	Rotary

Core Features

Rotary Joystick Support

• Rotary control is supported via gamepad or firmware written by atrac17 / DJ Hard Rich for LS-30 functionality using an RP2040. Latency verification done by misteraddons, for more information click here.

Model	Device	Connection	USB Polling Interval	Sample Number	Frame Probability	Average Latency	Joystick ID
LS-30 Rotary Encoder	RP2040	Wired USB	1ms	2241	95.52%	0.747 ms	2e8a:000a

Native Y/C Output

• Native Y/C ouput is possible with the analog I/O rev 6.1 pcb. Using the following cables, HD-15 to BNC cable will transmit Y/C over the green and red lines. Choose an appropriate adapter to feed Y/C (S-Video) to your display.

H/V Adjustments

• There are two H/V toggles, H/V-sync positioning adjust and H/V-sync width adjust. Positioning will move the display for centering on CRT display. The sync width adjust can be used to for sync issues (rolling) without modifying the video timings.

Scandoubler Options

• Additional toggle to enable the scandoubler without changing ini settings and new scanline option for 100% is available, this draws a black line every other frame. Below is an example.

Scandoubler Fx	Scanlines 25%	Scanlines 50%	Scanlines 75%	Scanlines 100%

Controls

• Service menu is accessed by holding the F2 key on boot. Service dip is functional for Ikari III. P.O.W. and SAR: Search and Rescue require holding the F2 key on boot. Street Smarts requires the service dip to be toggled before resetting the core and holding F2.

Game	Joystick	Service Menu	Control Type
P.O.W.	8-Way		Co-Op
Street Smart	8-Way		Co-Op
Ikari III	8-Way or Rotary		Co-Op
SAR	8-Way or Rotary		Co-Op

Rotary Joystick Support

• Rotary control is supported via gamepad or firmware written by atrac17 / DJ Hard Rich for LS-30 functionality using an RP2040. There are toggles in the OSD under Debug Settings to select the rotary controller type per player.
  
  When using a gamepad, enabling autofire and setting to 160ms for Rotate CW/CCW in the MiSTer framework allows for smooth rotation; adjust the rate to fit your preference. LS-30 firmware requires no mapping and is plug and play; it is player dependent and connected over USB to the DE10-Nano.

Keyboard Handler

• Keyboard inputs mapped to mame defaults for the following functions.

Services	Coin/Start
Functions Keymap Test F2 Reset F3 Service 9 Pause P	Functions Keymap P1 Start 1 P2 Start 2 P1 Coin 5 P2 Coin 6

Player 1	Player 2
Functions Keymap P1 Up Up P1 Down Down P1 Left Left P1 Right Right P1 Bttn 1 L-Ctrl P1 Bttn 2 L-Alt P1 Bttn 3 Space	Functions Keymap P2 Up R P2 Down F P2 Left D P2 Right G P2 Bttn 1 A P2 Bttn 2 S P2 Bttn 3 Q

Debug
Functions Keymap Text Layer (TXT) F7 Sprite Layer (FG) F8 Sprite Layer (BG) F9 Sprite Layer (OBJ) F10

• Custom keyboard inputs mapped for LS-30 RP2040 firmware functionality. The mapping is player dependent for the RP2040 firmware.

LS-30 Player 1	LS-30 Player 2
Functions Keymap P1 Rotary 1 Y P1 Rotary 2 U P1 Rotary 3 I P1 Rotary 4 O P1 Rotary 5 H P1 Rotary 6 J P1 Rotary 7 K P1 Rotary 8 L P1 Rotary 9 N P1 Rotary 10 M P1 Rotary 11 , P1 Rotary 12 .	Functions Keymap P2 Rotary 1 Z P2 Rotary 2 X P2 Rotary 3 C P2 Rotary 4 V P2 Rotary 5 B P2 Rotary 6 W P2 Rotary 7 E P2 Rotary 8 T P2 Rotary 9 3 P2 Rotary 10 4 P2 Rotary 11 7 P2 Rotary 12 8

Support

Please consider showing support for this and future projects via Darren's Ko-fi and atrac17's Patreon. While it isn't necessary, it's greatly appreciated.

Licensing

Contact the author for special licensing needs. Otherwise follow the GPLv2 license attached.