Memory Unit

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General Information

  • Memory Units (64 MB) require no setup or configuration. (Plug & Play)
  • Xbox 360 accepts two Memory Units.
  • Each unit contains three IC's:
  1. Custom Microsoft ASIC (marked as X805867-002)
  2. Samsung NAND flash memory (IC model depends on memory size i.e. K9F1208U)
  3. Perhaps an I2C EEPROM memory (marked as X803122)

Known Facts

  • The Memory card is required in absence of hard drive to play on Xbox Live and to save game progress.
  • The memory cards are USB devices, albeit with custom connectors and with 3.3V power (not 5V).

Inside the memory unit

Flash Contents

Address Length (bytes) Contains
0x00000 16 Text String "DUMBO FIL format"
0x0020B 5 5 byte value
0x04200 32 MS text string
0x04220 15 Ascii serial nr of MU
0x0440B 5 5 byte value
0x10800 ~ Data start

FATX Partition Locations

Address Type
0x00 Partition 1
0x7ff000 Partition 2


The connections of the small 8-pin IC:

Pin 1: GND (A0)
Pin 2: NC (A1)
Pin 3: NC (A2)
Pin 4: NC (GND)
Pin 5: to pin 22 of ASIC (SDA)
Pin 6: to pins 20 and 21 of ASIC (SCL)
Pin 7: to pin 3 of ASIC (WP)
Pin 8: VCC (3.3V)

At the bottom side of this chip is written:


Most plausible theory is that the IC is an I2C EEPROM memory. I've added in brackets possible 24CXXX family pin names. GND could be A0 because in most cases adress lines (A0-A2) are connected to ground.

Other theory (less plausible) is that it might be a NXP (Philips) P89LPC901FD microcontroller with its die upside down?

When supplying 3.3 volts to the Memory Unit:
Measurements at pins 5, 6, and 7 show that there is a clock signal of 5Mhz present on pin 7 (in burst of 16 cycles).
Every 16 cycles, one bit is transferred on pin 6.
3ms after powerup data communication ends.

Note: This looks like SPI, pin 7 - SCK, Pin 6 - /SS, Pin 5 - MODI.

But SPI needs four wires. It's more like I2C which needs only two lines (SDA, SCL) and optionally WP (Write Protect).