MechaCon

MechaCon is short for Mechanics Controller. The main function of it is to control the drive mechanism. However, this chip is also the security ic of the PlayStation 2 that implements game disk security, Magic Gate and KELF file decryption.

There are two known main variants of it.

The earlier one is based on SPC 9700 and used till GH-022. Chip name starts with "CXP10". Older versions come in a QFP package, newer versions in a BGA package.

The newer one is ARM based, codenamed "Dragon", and used from GH-023 (SCPH-5000X) onwards. Chip name starts with "CXR7". All versions come in a BGA package. Besides this, "Dragon" also includes the functions that were fulfilled by the separate SysCon chip on earlier boards up to GH-022, as well as the RTC+EEPROM chip, that was separate on earlier boards (or dedicated EEPROM and RTC chips on even earlier boards).

Both have access to a 1 KB / 512 words EEPROM. The EEPROM content is different between the SPC 9700 based MechaCon and Dragon.

For the SPC 9700 MechaCon, the EEPROM is an external chip; either a dedicated EEPROM chip on older boards or a combined Rohm RTC+EEPROM chip on later boards.
Dragon has the die of the combined Rohm RTC+EEPROM chip inside its own chip package, however, the EEPROM pins are exposed on the package, and the connection between Dragon and the RTC+EEPROM is done externally on the motherboard.

Every MechaCon has a 3.3 V TTL UART interface that was used by service centers for example to readjust the drive and to write calibration data etc. Today it can be used with tools like PMAP (currently supports consoles up to I-chassis) to readjust the drive mechanism after fitting a replacement laser assembly etc.

SPC 9700

Hardware revisions

• CXP101064 (only used on early A-chassis/GH-001 boards)
• CXP102064 (used from later A-chassis to D/D'-chassis boards)
• CXP103049 (BGA case, used in F and G-chassis)

The CXP103049 requires a working battery to function properly.

Firmware revisions

Firmware comes in an OTP or mask ROM inside MechaCon.

TODO

Dragon

Hardware revisions

• CXR706F080 (has a flash ROM for firmware; used for engineering, not used in retail consoles)
• CXR706080 (used in H, I and J chassis SCPH-5XXXX consoles as well as in PSX)
• CXR716080 (used in K, L and M slim chassis SCPH-70XXX, SCPH-75XXX and SCPH-77XXX consoles)
• CXR726080 (used in N, P and R slim chassis SCPH-79XXX and SCPH-9XXXX consoles)

Firmware revisions

Firmware comes in an OTP or mask ROM inside MechaCon, except in CXR706F080, which has a reprogrammable flash ROM. It is however possible to apply patches to it via EEPROM.

Dumps: https://mega.nz/folder/MNpAQDzJ#bZpyfb7aGrhGDMR_ZGA8ig

Early versions of the Dragon MechaCon firmware have a tendency to crash by sheer bad luck or on badly readable discs (e.g. badly burned/low quality DVD-R discs or scratched originals), overvolting the focus/tracking coils of the laser and killing them and also the driver IC in the process. Several hardware-based fixes have been developed by the community to address this issue with varying degrees of success.

EEPROM layout

Start (word)	End (word)	Size (byte)	Offset in file	Description
0	48	96	0x0
48	90	84	0x60
96	128	64	0xC0
128	150	44	0x100
160	190	60	0x140
192	198	12	0x180	Region params (only slim)
204	208	8	0x198	MAC address
211	216	10	0x1A6	wake up time
216	225	18	0x1B0	model number
227	232	10	0x1C6	Region code key seed
232	237	10	0x1D0	Region code ciphertext
240	245	10	0x1E0	iLink id
245	248	6	0x1EA	(used by scmd 3, subcmd 48 and 49)
248	253	10	0x1F0	Console id
253	256	6	0x1FA	(used by scmd 3, subcmd 48 and 49)
256	312	112	0x200	config 2
312	344	64	0x270	config 0
344	400	112	0x2B0	config 1
400	512	224	0x320	Rom patches ciphertext

Region code

Decryption

int getRegionFlags()
{
	// read kek
	uint8_t key508[8];
	ksGetKey(key508, 508);
	
	// read saved seed from eeprom
	uint8_t keyseed[10];
	eepromRead(227, sizeof(keyseed), keyseed);
	
	// read encrypted region from eeprom
	uint8_t ciphertext[10];
	eepromRead(232, sizeof(ciphertext), ciphertext);
	
	// generate key
	uint8_t key[8];
	desEncrypt(key508, keyseed, key);
	
	// decrypt ciphertext
	uint8_t plaintext[8];
	desDecrypt(key, ciphertext, plaintext);
	
	uint16_t crc = *(uint16_t *) plaintext;
	crc += *(uint16_t *) &plaintext[2];
	crc += *(uint16_t *) &plaintext[4];
	
	// check checksum
	if (crc  == *(uint16_t *) &plaintext[6])
		return *(uint32_t *) plaintext;
	
	retrun 0;
}

Bits

Bit	Description
0	Japan
1	USA
2	Europe
3	Oceania
4	Asia
5	Russia
6	China
7	Mexico
16	Development (changes MagicGate keys)
17	Retail MagicGate keys on Development, bypass BootCertify
18	Arcade (changes MagicGate keys)
19	Prototype? (changes MagicGate keys)
20	? (dvd related)

Rom patch

Decryption

bool readAndDecryptRomPatch()
{
	// read the patch's first half
	uint8_t patches[0xDE];
	eepromRead(400, 0x70, patches);
	
	// check if the -1th byte is 0 (sum is not checked)
	if (patches[0x6E])
		return false;

	// read the patch's second half
	eepromRead(456, 0x70, &patches[0x6E]);
	
	// check if the -1th byte is 0 (sum is not checked)
	if (patches[0xDC])
		return false;

	// read encryption key
	uint8_t key504[8];
	ksGetKey(key504, 504);
	
	// decrypt the patch using DES-ECB
	for (int i = 0; i < 0xD8; i += 8)
		desDecrypt(key504, &patches[i], &patches[i]);

	// check sum
	uint32_t sum = *(uint32_t *)patches;
	sum += *(uint32_t *)&patches[4];
	sum += *(uint32_t *)&patches[8];
	sum += *(uint32_t *)&patches[12];

	if (*(uint32_t *) &patches[0xD8] == ~sum)
		return false;
		
	return true;
}

Content

The patch can contain up to 4 patches.

addressX = The address where to apply the patch

valueX = The data that's written there

svc_addressX = The address where SVC X instruction jumps to.

payload = Arbitrary, could be code or data as well.

Offset	Size	Name
0x00	0x04	address0
0x04	0x04	address1
0x08	0x04	address2
0x0C	0x04	address3
0x10	0x04	value0
0x14	0x04	value1
0x18	0x04	value2
0x1C	0x04	value3
0x20	0x04	svc_address0
0x24	0x04	svc_address1
0x28	0x04	svc_address2
0x2C	0x04	svc_address3
0x30	0xA8	payload
0xD8	0x04	crc