Thread: Convert 3790/3760/3750 to 3490

Originally Posted by bpb

same funny I had.
now your unit also recovered the model number?

But now I'm investigating how to change UnitID and retain HWID.
And what I discovered:
UnitID stored in region 34 is decimal UnitID treated as "Unsigned long" and stored as Intel HEX. For example UnitID 1234567890 will be D2029649. In region 41 is applyed some "encryption". The bytes sequence stored in region 41 is the same bytes sequence from region 34 but XOR'ed with FF and then with C3 5A.
So the UnitID from region 34 (D2029649) in region 41 is stored like EEA7AAEC.
In region 41 from Nuvi 3490 there are 24 copies of this UnitID.
EDIT:
BTW in region 41 from unit which flashed from 3790 to 3490 there are 65 copies of UnitID.
NVRAM in 3490 is about 2MB and NVRAM in 3790 is about 6MB