Jaleco Mega System 1 A FPGA Implementation

FPGA compatible core of Jaleco's Mega System 1 A (P-47 based) arcade hardware for MiSTerFPGA written by Darren Olafson with assistance from atrac17. Verified against a authentic P-47: The Freedom Fighter PCB purchased by atrac17.

The intent is for this core to be a 1:1 playable implementation of the Mega System 1 A arcade hardware. Currently in beta state, this core is in active development. Additional Mega System 1 arcade titles will be in separate repositories (Mega System 1 Rev Z/B/C).

Supported Titles (Type-A)

Title	PCB Number	Encrypted Program	MCU	Status	Released
P-47: The Freedom Fighter	MB8844 MB8843	N/A	N/A	Implemented	20230701
Kick Off - Jaleco Cup	MB8844	N/A	N/A	Implemented / W.I.P	No
Shingen Samurai-Fighter / Takeda Shingen	MB8844	Yes	N/A	Implemented / W.I.P	No
Ninja Kazan / Iga Ninjyutsuden	MB8845	Yes	Yes	Implemented	20230923
The Astyanax / The Lord of King	MB8844 MB8845	Yes	Yes	Implemented	20230701
Hachoo!	MB8845	Yes	Yes	Implemented	20240101
Jitsuryoku!! Pro Yakyuu	MBMO2A	Yes	Yes	Implemented	20240106
Plus Alpha	MB8845	Yes	Yes	Implemented	20240106
Saint Dragon	MB8845	Yes	Yes	Implemented	20230715
Rod-Land	MBMO2A MB8845	Yes	N/A	Implemented	20230513
Phantasm	MB8845	Yes	N/A	Implemented	20230708
E.D.F: Earth Defense Force (Prototpe)	W.I.P	Yes	N/A	Implemented	20240101
In Your Face (Prototpe)	W.I.P	Yes	N/A	Implemented	20240101
Soldam	W.I.P	Yes	N/A	Implemented	20230519

External Modules

Module	Function	Author
fx68k	Motorola 68000 CPU	Jorge Cwik
fx68k	Motorola 68000 CPU	Jorge Cwik
jt51	Yamaha YM2151	Jose Tejada
jt6295	OKI MSM6295	Jose Tejada
jt6295	OKI MSM6295	Jose Tejada
yc_out	Y/C Video Module	Mike Simone
mem	SDRAM Controller / Rom Downloader	Josh Bassett, modified by Darren Olafson
core_template	MiSTer Framework Template	sorgelig, modified by Darren Olafson / atrac17

Known Issues / Tasks

• OKI playback; correct samples (ROM board dependent) [Issue]

• Mosaic OBJ effects verify against PCB (P-47 JALECO logo) [Task]

• OBJ Scroll effects verify against PCB (P-47 trail effect) [Task]

• Screen flip implementation [Task]

• Verify H-FLIP / V-FLIP for screen flip against PCB [Task]

• Program CPU overclock toggle [Task]

• OPM / ADPCM audio mix toggles [Task]

• Verify analog timings from MB8842 mother board [Task]

• Measure HBL, VBL, H-SYNC, and V-SYNC timings from MB8842 mother board [Task]

• 64-Bit SDRAM controller access for sprites [Task]

PCB Check List

Clock Information

H-Sync	V-Sync	Source	PCB Number
15.625kHz	56.205035	DSLogic+	MB8842

Crystal Oscillators

Freq (MHz)	Use	PCB Number
4.000 MHz	OKI MSM6295 / MCU CLKS (4 MHz)	ROM Board (See PCB Number)
7.000 MHz	M68000 AUDIO CLOCK (7MHz) YM2151 CLK (3.5 MHz)	MB8842
12.000 MHz	M68000 CPU CLK (6 MHz) Pixel CLK (6 MHz)	MB8842

Pixel clock: 6.00 MHz

Estimated geometry:

384 pixels/line  

278 lines/frame  

Main Components

Chip	Use	PCB Number
Motorola 68000 CPU	Main CPU	MB8842
Motorola 68000 CPU	Audio CPU	MB8842
Yamaha YM2151	OPM Sound	MB8842
OKI MSM6295	ADPCM Sound	ROM Board (See PCB Number)
OKI MSM6295	ADPCM Sound	ROM Board (See PCB Number)

Custom Components

Chip	Function
NEC D65005GB200	Custom Gate-Array / OBJ
NEC D65005GB249	Custom Gate-Array / SYNC
NEC D65012GF303	Custom Gate-Array / VCTR
NEC D65012GF307	Custom Gate-Array / SCPT

Core Features

Refresh Rate Compatibility Option

• Video timings can be modified if you experience sync issues with CRT or modern displays; this will alter gameplay from it's original state.

Refresh Rate	Timing Parameter	HTOTAL	VTOTAL
15.63kHz / 56.2Hz	MB8842	384	278
15.63kHz / 59.4Hz	NTSC (Closest Spec)	384	263

• MAME information for timing parameters is incorrect.

Refresh Rate	Timing Parameter	HTOTAL	VTOTAL
14.77kHz / 56.2Hz	MAME	406	263

P1/P2 Input Swap Option

• There is a toggle to swap inputs from Player 1 to Player 2. This only swaps inputs for the joystick, it does not effect keyboard inputs.

Audio Options

• There is a toggle for mixing audio from mono to stereo; MB8842 had this option via dipswitch.

• There are toggles to disable playback of OPM and ADPCM audio or raise the mixing volume the OPM and ADPCM audio channels.

Overclock Options

• There is a toggle to increase the M68000 frequency from 6MHz to 7.2MHz; this will alter gameplay from it's original state addressing native slowdown of gameplay.

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, flagging etc) 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%

PCB Information / Control Layout

Title	Joystick	Service Menu	Dip Switches	Shared Controls	Dip Default	PCB Information
P-47: The Freedom Fighter	8-Way	Service Menu	Dip Sheet	Co-Op	N/A	Coming soon
Ninja Kazan / Iga Ninjyutsuden	8-Way	Service Menu	Dip Sheet	Turn Based	N/A	Coming soon
Phantasm	8-Way	Service Menu	Dip Sheet	Turn Based	N/A	Coming soon
Saint Dragon	8-Way	Service Menu	Dip Sheet	Turn Based	N/A	Coming soon
The Astyanax / The Lord of King	8-Way	Service Menu	Dip Sheet	Co-Op	N/A	Coming soon
Rod-Land	8-Way	Service Menu	Dip Sheet	Co-Op	N/A	Toggling the "Chapter" dipswitch will go from the "First Story (Rescue My Mom)" to the "Second Story (The Unknown Pyramid)". You can also insert a coin and press up, up, up, down, down, down, start to enable the second story or up, up, up, down, down, down start to return to the first story on English versions. For Japanese versions, the code is reversed for accessing the second story and returning to the first. There are three endings to Rod-Land, complete the 31 levels in the first story or second; for the special ending, play either story by inputing the secret code and beating the extra level (32).
Soldam	8-Way	Service Menu	Dip Sheet	Versus	N/A	Coming soon
Jitsuryoku!! Pro Yakyuu	8-Way	Service Menu	Dip Sheet	Versus	N/A	Coming soon
Hachoo!	8-Way	Service Menu	Dip Sheet	Co-Op	N/A	Coming soon
E.D.F: Earth Defense Force (Prototpe)	8-Way	Service Menu	Dip Sheet	Co-Op	N/A	Coming soon
In Your Face (Prototpe)	8-Way	Service Menu	Dip Sheet	Versus	N/A	Coming soon
Plus Alpha	8-Way	Service Menu	Dip Sheet	Co-Op	N/A	Coming soon

Keyboard Handler

• Keyboard inputs mapped to mame defaults for Player 1 / Player 2.

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 P1 Bttn 4 L-Shift	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 P2 Bttn 4 W

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.