(bad?) DMK/PDI dump of Gize!/XIX - need advice...

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By max_iwamoto

Champion (466)

max_iwamoto's picture

28-07-2019, 03:46

shram86 wrote:

All right max and co, got another undumped, heavily protected game for you.
Sailor Fuku Senshi Feris (DMK+DSK)
I think on this one all 3 disks are protected.

Dump info:
DMK disk 1:
CRC fails on side 2 for tracks 19, 20 and 24
CRC fails on both sides for tracks 21, 22 and 23
disk 2: OK
disk 3: N (not readable?) on both sides for tracks 62-80

DSK disk 1:
CRC fail on tracks 22, 23
disk 2 OK
disk 3 OK

DMKs playable in openMSX but the intro is glitchy.

If DMK glochy it might mean some data is corrupted. But I will start with DSK first because by your description it looks like a better dump. Will update you as soon as possible.

By max_iwamoto

Champion (466)

max_iwamoto's picture

28-07-2019, 16:35

Feris is ready. I am adding Turbo mode to it as well, because game is very slow without it. And DSK version looks like a good dump without GFX glitches.

in DEMO picture:

in GAME picture:

By shram86

Expert (88)

shram86's picture

28-07-2019, 17:10

Sweet. I tried playing from the real disk last night but the loading was getting worse and worse and more and more glitches would happen. I think the dsk version is the best I can get from the disks.

Again any explanation of what you see protection wise would be great Wink

By max_iwamoto

Champion (466)

max_iwamoto's picture

28-07-2019, 17:42

shram86 wrote:

Sweet. I tried playing from the real disk last night but the loading was getting worse and worse and more and more glitches would happen. I think the dsk version is the best I can get from the disks.

Again any explanation of what you see protection wise would be great Wink

I will post detailed explanation as before, just a bit busy with work at the moment. In next few days, I will upload all patches updated with Turbo mode and few other things.

For now I can say that 2nd and 3rd game have slightly different and longer protection than the 1st game, but in general same idea. Just different tracks/sectors and more encrypted code.

By Manuel

Ascended (15684)

Manuel's picture

09-08-2019, 21:33

These look like 'cheap PC88 ports'.... mostly only 8 colors on screen, using screen 7.

By shram86

Expert (88)

shram86's picture

10-08-2019, 00:15

They definitely are. The PC88 versions appear to be the "main" releases.

By max_iwamoto

Champion (466)

max_iwamoto's picture

11-08-2019, 23:42

Here is the patch to remove protection for DISK A of the COSMIC PSYCHO.

https://drive.google.com/open?id=1HXVwW_pVSWGd9_EJQhhmJ6tHeL...

---

Unfortunately, as mentioned above, game was ported from PC88 and adding Turbo mode messing it up (a big chunk of the game needs to be re-written).

---

Protection here is more sophisticated. Game decrypt parts of decrypting code (except small part at the end). It located from D831h to D96F. Also 2 parts of it decode code/data from B400h where game jumps after decrypting. While decoding code starting from B400h game also decrypting over decrypting code as well. In between decrypting sequences it planting a code at B400h JP C0E3h (where it going after RET at the end of decryption). So, we modifying code to just decrypt twice game code / data at B400h and removing all other unnecessary decryption code. This code located on DISK from offset 75E31h. Here is how it looks now:

_D831:
	POP	HL
	LD	SP,B3FEh
	LD	L,00h
	PUSH	HL

	LD	HL,B403h
	LD	DE,4A6Dh
	LD	BC,2430h	; default = 24A2h

.loop_1:
	CALL	_D958
	XOR	(HL)
	RLCA
	LD	(HL),A
	INC	HL
	DEC	BC
	LD	A,B
	OR	C
	JR	NZ,.loop_1
;
	LD	A,C3h
	LD	(B400h),A
;
	LD	HL,B403h
	LD	DE,3F1Ah
	LD	BC,2430h	; default = 2508h

.loop_2:
	CALL	_D958
	XOR	(HL)
	RLCA
	LD	(HL),A
	INC	HL
	DEC	BC
	LD	A,B
	OR	C
	JR	NZ,.loop_2
;
	LD	HL,C0E3h
	LD	(B401h),HL
;
	RET


_D958:
	PUSH	HL
	PUSH	DE
	POP	HL
	ADD	HL,HL
	ADD	HL,DE
	ADD	HL,HL
	ADD	HL,DE
	LD	E,H
	LD	D,L
	RLC	H
	RLC	H
	RRC	L
	ADD	HL,DE
	LD	DE,1119h
	ADD	HL,DE
	EX	DE,HL
	LD	A,D
	POP	HL
	RET

By shram86

Expert (88)

shram86's picture

13-08-2019, 00:34

Awesome... These algorithms are pretty fascinating.

By PAC

Guardian (5235)

PAC's picture

14-08-2019, 19:17

There seems to be a graphic corruption in disk A of Cosmic Psycho just when main presentation finishes. Similar than Gize! / XIX. BTW thank you for your work max_iwamoto. Wink

By max_iwamoto

Champion (466)

max_iwamoto's picture

19-08-2019, 03:02

PAC wrote:

There seems to be a graphic corruption in disk A of Cosmic Psycho just when main presentation finishes. Similar than Gize! / XIX. BTW thank you for your work max_iwamoto. Wink

I didn't see any graphic corruptions... Could you let me know what config did you use?

Max

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