Not much is know about how to mess with the T2 chip.
The T2 loads it's 'Brige-OS' from a small (32Mbit 3x4mm) ROM located near the T2 Chip. The BIOS for the Mac is not located on that ROM.
The T2 Chips is essentially an iPhone CPU that handles the Flash memory. Hence it would not be very surprising if the Mac BIOS is stored on the Flash memory.
The T2-ROM does hold the serial number of the Mac as well as of the Motherboard.
The Medusa can read and write the T2-ROM. You will need the extra '1.8v Level Shifter' and you will have to solder the ROM off the motherboad and onto the Level Shifter to do so.
When the Medusa (Firmware 3.3 or later) is presented with a T2-ROM it will recognise that it is a T2-ROM and show the Mac serial number and the Motherboard serial number. It is possible to edit the Mac serial number. WARNING! as very little is know about the T2 chip editing anything can have catastrophic results. Always make a backup of your ROM beforehand and don't blame us if anything goes wrong!
It is relatively easy to 'clean' the T2 ROM. To do that put the Mac in DFU mode. Then restore the BridgeOS using Apple Configurator 2.
A4069 Level Shifter to 1.8 volt with Solder Spaces
PCB (5cm x 5cm) with space to solder ROM chip and 8-pin EF connector. Supports SOP8 (SOIC8), WSON 6x8 and WSON 5x6 SPI ROM chips as well as the much smaller WSON 2x3, WSON 3x4 and the BGA ROM chips as uses in the MacBook A1534 (for the EFI and for the SSD).
This board also has a level shifter on board for changing the 3v3 signals as supplied by the Medusa-3 to 1.8 volt signals.
There are three ways to use this board:
1) Connect 3v3 side to Medusa and 1v8 side to external 1v8 ROM. For example using a Pomona clip to clip onto the ROM in a Samsung Chromebook.
2) Connect 3v3 side to Medusa and solder a 1v8 ROM onto this board. For example the SSD ROM (U8800) from a A1534 820-00045 board.
3) Use it as a solder board for 3v3 ROMs by ignoring the level shifter. For example connect the 1v8 side to Medusa (which connect directly to the soldered ROM) and solder the EFI ROM (U6100) from a A1534 820-00045 board (which is 3v3).
ROM Chips Adesto (Blank) 32Mbit 1.8volt 3x4mm
We can supply theblank Adesto version of the T2-ROM chip. Apple uses more than one brand for these ROMs. So far we can supply one kind. They are interchangeable.
In case you want to play around with the T2-ROM here is your chance!
A4070 Solder Board for WSON 3x4 and 5x6
PCB (blue 5cm x 5cm) with space to solder ROM chip and 8-pin EF connector. Supports WSON 3x4 and WSON 5x6 SPI ROM chips.
This board allows you to read and write loose ROM chips. Only have one chip soldered onto this board at a time. You can read or write the ROM by connecting this Solder Board to the Medusa via the JST connector. If you want you can add pull-up resistors (10kΩ) for the Hold and WP pins. For use with Medusa this is not necessary. Many places for each model in case you damage one…